Patent Publication Number: US-9901474-B2

Title: Anti-obesity devices

Description:
This application is a continuation of U.S. application Ser. No. 13/430,949, filed Mar. 27, 2012, which is a continuation of U.S. application Ser. No. 11/635,890, filed Dec. 8, 2006, now U.S. Pat. No. 8,486,153, which is a divisional of U.S. application Ser. No. 11/541,616, filed Oct. 2, 2006, now U.S. Pat. No. 7,766,861, which is a divisional of U.S. application Ser. No. 10/726,011, filed on Dec. 2, 2003, now U.S. Pat. No. 7,122,058, which claims the benefit of U.S. Provisional Application No. 60/512,145, filed on Oct. 17, 2003. 
     The entire teachings of the above applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     According to the Center for Disease Control (CDC), over sixty percent of the United States population is overweight, and almost twenty percent are obese. This translates into 38.8 million adults in the United States with a Body Mass Index (BMI) of 30 or above. The BMI is defined as a person&#39;s weight (in kilograms) divided by height (in meters), squared. To be considered clinically, morbidly obese, one must meet one of three criteria: BMI over 35, 100 lbs. overweight or 100% above ideal body weight. There is also a category for the super-obese for those weighing over 350 lbs. 
     Obesity is an overwhelming health problem. Because of the enormous strain associated with carrying this excess weight, organs are affected, as are the nervous and circulatory systems. In 2000, the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK) estimated that there were 280,000 deaths directly related to obesity. The NIDDK further estimated that the direct cost of healthcare in the US associated with obesity is $51 billion. In addition, Americans spend $33 billion per year on weight loss products. In spite of this economic cost and consumer commitment, the prevalence of obesity continues to rise at alarming rates. From 1991 to 2000, obesity in the US grew by 61%. Not exclusively a US problem, worldwide obesity ranges are also increasing dramatically. 
     One of the principle costs to the healthcare system stems from the co-morbidities associated with obesity. Type-2 diabetes has climbed to 7.3% of the population. Of those persons with Type-2 diabetes, almost half are clinically obese, and two thirds are approaching obese. Other co-morbidities include hypertension, coronary artery disease, hypercholesteremia, sleep apnea and pulmonary hypertension. 
     Although the physiology and psychology of obesity are complex, the medical consensus is that the cause is quite simple—an over intake of calories combined with a reduction in energy expenditures seen in modern society. While the treatment seems quite intuitive, the institution of a cure is a complex issue that has so far vexed the best efforts of medical science. Dieting is not an adequate long-term solution for most people. Once an individual has slipped past the BMI of 30, significant changes in lifestyle are the only solution. 
     There have been many attempts in the past to surgically modify patients&#39; anatomies to attack the consumption problem by reducing the desire to eat. Stomach saplings, or gastroplasties, to reduce the volumetric size of the stomach, therein achieving faster satiety, were performed in the 1980&#39;s and early 1990&#39;s. Although able to achieve early weight loss, sustained reduction was not obtained. The reasons are not all known, but are believed related to several factors. One of which is that the stomach stretches over time increasing volume while psychological drivers motivate patients to find creative approaches to literally eat around the smaller pouch. 
     There are currently two surgical procedures that successfully produce long-term weight loss; the Roux-en-Y gastric bypass and the biliopancreatic diversion with duodenal switch (BPD). Both procedures reduce the size of the stomach plus shorten the effective-length of intestine available for nutrient absorption. Reduction of the stomach size reduces stomach capacity and the ability of the patient to take in food. Bypassing the duodenum makes it more difficult to digest fats, high sugar and carbohydrate rich foods. One objective of the surgery is to provide feedback to the patient by producing a dumping syndrome if they do eat these food products. Dumping occurs when carbohydrates directly enter the jejunum without being first conditioned in the duodenum. The result is that a large quantity of fluid is discharged into the food from the intestinal lining. The total effect makes the patient feel light-headed and results in severe diarrhea. For reasons that have not been determined the procedure also has an immediate therapeutic effect on diabetes. 
     Although the physiology seems simple, the exact mechanism of action in these procedures is not understood. Current theory is that negative feedback is provided from both regurgitation into the esophagus and dumping when large volumes of the wrong foods are eaten. Eventually, patients learn that to avoid both these issues they must be compliant with the dietary restrictions imposed by their modified anatomy. In the BPD procedure, large lengths of jejunum are bypassed resulting in malabsorption and therefore, reduced caloric uptake. In fact, the stomach is not reduced in size as much in the BPD procedure so that the patient is able to consume sufficient quantities of food to compensate for the reduced absorption. This procedure is reserved for the most morbidly obese as there are several serious side effects of prolonged malabsorption. 
     Unfortunately, these procedures carry a heavy toll. The morbidity rate for surgical procedures is alarmingly high with 11% requiring surgical intervention for correction. Early small bowel obstruction occurs at a rate of between 2-6% in these surgeries and mortality rates are reported to be approximately 0.5-1.5%. While surgery seems to be an effective answer, the current invasive procedures are not acceptable with these complication rates. Laparoscopic techniques applied to these surgeries provide fewer surgical complications but continue to expose these very ill patients to high operative risk in addition to requiring an enormous level of skill by the surgeon. Devices to reduce absorption in the small intestines have been proposed (See U.S. Pat. No. 5,820,584 (Crabb), U.S. Pat. No. 5,306,300 (Berry) and U.S. Pat. No. 4,315,509 (Smit)). However, these devices have not been successfully implemented. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method and apparatus for the application of a barrier sleeve in the digestive tract to limit absorption of food products in specific parts of the digestive tract and to provide negative feedback to patients with morbid obesity enabling them to modify their heating habits. 
     A gastrointestinal implant device can be inserted endoscopically in combination with a delivery catheter. The delivery catheter includes a catheter for passage through the intestines and a spherically shaped element coupled to the distal end of the catheter. The spherically shaped element may be remotely releasable. 
     A delivery system for placing a gastrointestinal implant device in a body includes an outer sheath in the proximal portion of the delivery system for storing a proximal portion of the gastrointestinal implant device. The proximal portion of the gastrointestinal implant device includes an anchoring device for anchoring the device in the stomach. The delivery system includes an inner sheath within the outer sheath. The inner sheath extends beyond the outer sheath toward the distal end of the delivery system. A first lumen is within the inner sheath for passing the outer sheath over a guidewire and a second lumen is within the inner sheath for moving a moveable element to secure the distal end of a sleeve coupled to the stent to the inner sheath. The delivery system also includes a release mechanism to release the anchoring device from the outer sheath. A sleeve release mechanism is coupled to the moveable element for releasing the distal end of the sleeve. There is a spherical shaped element at the distal end of the delivery system which is held by the moveable element. 
     The moveable element may be a sleeve retention wire, which exits the second lumen and pierces the distal end of the sleeve. The sleeve release mechanism pulls the outer sheath toward the proximal end of the delivery system to remove the outer sheath from the anchoring device. The sleeve release mechanism pulls the moveable element toward the proximal end of the delivery system to release the distal end of the sleeve after the anchoring device has been released. 
     A distal portion of the sleeve may be stored in a pill for delivery and the distal portion of the sleeve is released from the pill by peristalsis. The distal portion of the sleeve may be stored in a dissolvable pill for delivery. The spherical shaped element is attached to an element retention wire which is held by the moveable element. The moveable element may be looped through the spherical shaped element, the distal end of the moveable element may be coiled and stored within the spherical shaped element or the moveable element may be held in an S-shaped track within the spherical shaped element. 
     The spherical shaped element at the distal end of the delivery system may be an expandable balloon. The element may be remotely releasable. The inner sheath may include a third lumen through which a fluid is passed to release the sleeve from the distal end of the delivery device. The sleeve release mechanism pulls the moveable element toward the proximal end of the delivery system to release the spherical shaped element after the anchoring device has been released. 
     A gastrointestinal implant device includes a flexible sleeve and a collapsible anchor coupled to a proximal end of the sleeve. The flexible sleeve is open at both ends, and adapted to extend into the duodenum to limit absorption of nutrients in the duodenum. The anchor includes two spaced apart rings of differing diameters to anchor the proximal portion of the sleeve in the stomach. The rings may be made from Nitinol and may include at least two stabilizing ears and may be formed by loosely intertwined wires. The rings may be linked with a connecting bar. The connecting bar includes extensions extending from the exterior surface of the bar for anchoring the proximal portion of the sleeve in the stomach. Extensions extending from the exterior surface of a proximal ring and extensions extending from the exterior surface of a distal ring are angled towards each other. The anchor is covered by a proximal portion of the sleeve. 
     The interior surface of the ring is covered by the sleeve and the exterior surface of the ring is coated with polyurethane. The rings are folded in a u-shape stored in a delivery tube to insert the flexible sleeve. 
     The sleeve may be impregnated with an anti-hunger hormone such as peptide-YY. The sleeve may be impregnated with a drug that reduces inflammation. The distance between the rings may be selected to hold the pylorus open. The sleeve may be formed of low friction materials such as cast polytetrafluoroethylene, polytetrafluoroethylene, cast fluoronated ethylene propylene with polytetrafluoroethylene coating, extruded fluoronated ethylene propylene and extruded perfluoroalkoxy. 
     The gastrointestinal implant device can be used as a method for treating intestinal bowel disease. A flexible sleeve is anchored within the stomach. The sleeve is open at both ends and impregnated with a drug that reduces inflammation. The flexible sleeve is into the jejunum. 
     The gastrointestinal implant device can be used as a method for treating obesity. A flexible sleeve is anchored within the stomach. The sleeve is open at both ends and enhanced with anti-hunger hormones and the flexible sleeve is extended into the duodenum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
         FIG. 1  is a sectional view of a portion of the digestive tract in a body; 
         FIG. 2  is a perspective view of a gastrointestinal implant device according to the principles of the present invention; 
         FIG. 3A  is a plan view of the proximal portion of the gastrointestinal implant device shown in  FIG. 2 ; 
         FIG. 3B  is a cross-sectional view as taken along line A-A of  FIG. 3A  showing the stent and first inner layer and second outer layer of the sleeve shown in  FIG. 2 ; 
         FIG. 4  is a perspective view of the gastrointestinal implant device with the second outer layer of the sleeve removed; 
         FIG. 5  is a sectional view of a body showing the gastrointestinal implant device implanted in the digestive system; 
         FIG. 6  is a perspective view of a collapsible self-expanding stent in the gastrointestinal implant device; 
         FIG. 7  is a perspective view of the stent shown in  FIG. 6  when compressed; 
         FIG. 8  is a perspective view of another embodiment of a stent when compressed; 
         FIG. 9  is a perspective view of the stent shown in  FIG. 8  with the strut ends bent to provide opposed barbs; 
         FIG. 10  is a perspective view of the stent shown in  FIG. 8  when expanded; 
         FIG. 11  illustrates the gastrointestinal device shown in  FIG. 1  including an anti-buckling mechanism; 
         FIG. 12  is a perspective view of a catheter system for delivery of the gastrointestinal implant device; 
         FIG. 13  is a cross-sectional view of the inner shaft taken along line E-E of  FIG. 12 ; 
         FIG. 14A  is an expanded perspective view of the dead-bolt mechanism shown in  FIG. 12 ; 
         FIG. 14B  is a sectional view of the dead-bolt mechanism shown in  FIG. 13A  illustrating the sleeve retention wire threaded through the sleeve; 
         FIG. 15  is sectional view of a portion of the catheter system illustrating the collapsed stent stored inside the outer sheath; 
         FIG. 16A  is a plan view of the catheter system illustrating the collapsed stent stored inside the outer sheath of the gastrointestinal implant device; 
         FIG. 16B  is a plan view of the catheter system illustrating the gastrointestinal implant device after release of the stent from the outer sheath; 
         FIG. 16C  is a plan view of the catheter system illustrating the expanded gastrointestinal implant device after the sleeve retention wire has been released; 
         FIG. 17  is a perspective view of another embodiment of the catheter system shown in  FIG. 12 ; 
         FIG. 18  is a sectional view of an everting catheter system for delivery of a longer length sleeve; 
         FIG. 19  is a perspective view of a retrieval device for removing the gastrointestinal implant device from the digestive tract; 
         FIG. 20  is a perspective view of the removal device engaged with the stent; 
         FIG. 21  is a perspective view of another embodiment of a gastrointestinal implant device; 
         FIG. 22  is a perspective view of the anchoring ring shown in  FIG. 21 ; 
         FIG. 23  is a perspective view of the anchoring ring shown in  FIG. 21  in a collapsed position for insertion and removal; 
         FIG. 24  is a perspective view of an anchor for anchoring the collapsible ring shown in  FIG. 23  to the muscular tissue of the pyloric section of the stomach; 
         FIG. 25A  is a perspective view of a delivery system for delivering the anchor after the gastrointestinal implant device has been placed in the stomach; 
         FIG. 25B  is a plan view of the delivery system shown in  FIG. 25A ; 
         FIG. 25C  is a cross-sectional view of the distal end of the catheter as taken along line B-B of  FIG. 25A ; 
         FIG. 25D  is a perspective view of the gastrointestinal implant device illustrating the anchor engaged with the tissue; 
         FIG. 25E  is an isometric view illustrating the barb engaging the tissue after delivery; 
         FIG. 26A  is a plan view of the delivery system including a snare wire for holding the distal end of the sleeve in position; 
         FIG. 26B  is a cross-sectional view taken along line CC of  FIG. 26A  through the inner sheath; 
         FIG. 26C  is a cross-sectional view taken along line DD of  FIG. 26A  through the outer sheath showing the inner sheath within the outer sheath; 
         FIG. 26D  is a cross-sectional view through the distal portion of the catheter showing the snare capturing the distal end of the sleeve; 
         FIG. 26E  is a sectional view through the distal portion of the catheter showing the snare locking mechanism; 
         FIG. 27  is a perspective view of the distal portion of the gastrointestinal implant device including texturing at the distal end; 
         FIG. 28  is a perspective view of a gastrointestinal implant device with another embodiment of an anchoring device; 
         FIG. 29  is a plan view of one of the rings in the gastrointestinal implant device shown in  FIG. 28 ; 
         FIG. 30  is a perspective view of the gastrointestinal implant device shown in FIG. in a collapsed position in a delivery tube for delivery into the body; 
         FIG. 31  is a perspective view of the gastrointestinal implant device illustrating the deployment of the distal ring from the delivery tube shown in  FIG. 30 ; 
         FIG. 32  is a perspective view of the gastrointestinal implant device after the deployment of the distal ring prior to deployment of the proximal ring; 
         FIG. 33  is a perspective view of the gastrointestinal implant device shown in  FIG. 28  with an alternative embodiment of an anchoring device; 
         FIG. 34  is a plan view of the gastrointestinal implant device shown in  FIG. 33 ; 
         FIG. 35  is a perspective view of another embodiment of one of the anchoring rings shown in  FIG. 28 ; 
         FIG. 36  is a perspective view of a gastrointestinal implant device with yet another embodiment of an anchor; 
         FIG. 37  is a perspective view of the anchor shown in  FIG. 36  with the sleeve removed; 
         FIG. 38  is a perspective view of the gastrointestinal device shown in  FIG. 36  in a collapsed position in a delivery tube for delivery into the body; 
         FIG. 39  is a perspective view of a delivery system illustrating the deployment of the distal ring  2803  from the delivery tube; 
         FIG. 40A  is a plan view of the gastrointestinal device shown in  FIG. 38  with additional anti-rotation and locking features; 
         FIG. 40B  is a perspective view of the anchor shown in  FIG. 40A  without the sleeve; 
         FIG. 41  is a perspective view of an alternative embodiment of a gastrointestinal implant device shown in  FIG. 28 . 
         FIG. 42A  is a perspective view of a portion of a catheter system for delivery of a gastrointestinal implant device; 
         FIG. 42B  is a cross-sectional view of the catheter shaft taken along line  42 B- 42 B of  FIG. 42A ; 
         FIG. 43  is a sectional view of a portion of the digestive tract in a body illustrating the position of a gastroscope/guide tube assembly; 
         FIG. 44  is a sectional view of a portion of the digestive tract in a body illustrating the distal end of the catheter extending from the distal end of the guide tube  4300 ; 
         FIG. 45  is a sectional view of a portion of the digestive tract in a body after the gastroinstestinal implant device of  FIG. 28  has been delivered; 
         FIG. 46  is a plan view of the distal end of the catheter system illustrating a releasable ball tip mechanism; 
         FIG. 47  is a plan view of the distal end of the catheter illustrating an alternative embodiment of a releasable ball tip mechanism; 
         FIG. 48  is a plan view of the distal end of the catheter illustrating yet another embodiment of a releasable ball tip mechanism; 
         FIG. 49  is a cross sectional view of an alternative embodiment of a solid spherical shaped element; 
         FIG. 50A  is a plan view of the distal end of the catheter with an inflatable spherical shaped element; 
         FIG. 50B  is a plan view of the distal end of the catheter after the inflatable spherical shaped element has been inflated; 
         FIG. 51  is a plan view of an alternative delivery system for delivering a gastrointestinal implant device; 
         FIG. 52  is a plan view of another embodiment of the delivery mechanism shown in  FIG. 51 ; and 
         FIGS. 53A-53C  illustrate a method for delivering an alternate embodiment of the catheter system  4250  having a central lumen for placement over a guide wire. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A description of preferred embodiments of the invention follows. 
       FIG. 1  is a sectional view of a portion of the digestive tract in a body. Food to be digested enters the stomach  102  through the cardiac orifice  110  from the esophagus. Chyme, a semi-fluid, homogeneous creamy or gruel-like material produced by gastric digestion in the stomach exits the stomach through the pyloric orifice (pylorus)  108  and enters the small intestine  112 . The pylorus  108  is a distal aperture of the stomach  102  surrounded by a strong band of circular muscle. The small intestine, about nine feet in length, is a convoluted tube, extending from the pylorus to the ileo-caecal valve where it terminates in the large intestine. The small intestine has three sections, the duodenum  104 , jejunum  106  and the ileum (not shown). The first eight to ten inch section of the small intestine, the duodenum, is the shortest, widest and most fixed part of the small intestine. 
     The duodenum has four sections: superior, descending, transverse and ascending which typically form a U-shape. The superior section is about two inches long and ends at the neck of the gall bladder. The descending section is about three to four inches long and includes a nipple shaped structure (papilla of vater)  114  through which pancreatic juice from the pancreas and bile produced by the liver and stored by the gall bladder enter the duodenum from the pancreatic duct. The pancreatic juice contains enzymes essential to protein digestion and bile dissolves the products of fat digestion. The ascending section is about two inches long and forms the duodenal-jejunal flexure  116  where it joins the jejunum  106 , the next section of the small intestine. The duodenal-jejunal flexure  116  is fixed to the ligament of Treitz  118  (musculus supensionus duodeni). The juices secreted in the duodenum break the partially digested food down into particles small enough to be absorbed by the body. The digestive system is described in Gray&#39;s Anatomy (“Anatomy of the Human Body”, by Henry Gray) and “Human Physiology”, Vander, 3 rd  ed, McGraw Hill, 1980, the contents of which are incorporated herein by reference in their entirety. 
       FIG. 2  is a perspective view of a gastrointestinal implant device  200  according to the principles of the present invention. The gastrointestinal implant device  200  includes an elongated open-ended flexible sleeve or tube  202  having a first proximal opening  204  and a second distal opening  206 . Within the sleeve  202  is a passageway that extends from the first proximal opening  204  to the second distal opening  206  for transporting the chyme exiting the stomach  102  ( FIG. 1 ). The surface of the passageway (the interior surface of the implant device  200 ) is smooth to enable the chyme to easily pass through. The exterior surface of the implant device  200  is smooth to prevent tissue in-growth and to be non-irritating to the bowel. 
     Within the implant device  200  at the proximal end including the first proximal opening  204  is a collapsible self-expanding stent  208 . The stent  208  includes a plurality of opposed barbs  210  for anchoring the implant device  200  to the muscular pylorus in the stomach  102 . The diameter of the stent  208  is dependent on the diameter of the pyloric orifice  108  ( FIG. 1 ) about 0.8″ to 1.1″ based on human anatomy variations. In one embodiment, the length l of the stent  208  is selected to extend through the pylorus  108  and keep the pylorus  108  permanently open to induce “dumping syndrome”. In an alternate embodiment, a stent with a shorter length l allows the pylorus  108  to open and close normally. 
     The sleeve material is thin and conformable so that it collapses in the intestine to a small volume to minimize bowel irritability. It has a low coefficient of friction (&lt;0.20) so that chyme slides easily through it and the bowel slides easily around it. It is of low permeability to fluids so that the chyme does not touch the bowel wall and the digestive enzymes do not significantly breakdown the chyme. It is biologically inert and non-irritating to the tissues. One such material is expanded polytetrafluoroethylene (ePTFE) with a wall thickness of about 0.006″ and an internodal distance of 20 microns. This material is hydrophobic but is slightly porous. However, these very small pores may plug over time. The porosity may be reduced by coating the material on the inside, outside or in the pores with dilute solutions of silicone or polyurethane. Another material is polyethylene with a wall thickness of less than 0.001″. Other materials include Cast PTFE (polytetrafluoroethylene, Teflon), Cast PTFE with FEP (fluoronated ethylene propylene) or PFA (Perfluoroalkoxy) coating to minimize pin holes, Extruded FEP and Extruded PFA. These materials are solid and non-porous in contrast to ePTFE which is porus, but these materials are also considered to be Teflons. Rubber-like materials typically have friction coefficients of 1-4, significantly stickier than these materials. However, in alternate embodiments other materials having similar characteristics can be used. 
     The sleeve  202  includes two layers of material at least at the proximal end. A first outer layer covers the exterior of the stent. The second inner layer covers the interior surface of the stent  208 . The barbs  210  protrude from the exterior surface of the stent  208  through the first outer layer of the sleeve  208 . The holes in the first outer layer through which the barbs  210  protrude are filled with an impervious material such as silicone or urethane to limit mixing of digestive juices with the chyme flowing through the passageway. The diameter of the sleeve  208  is selected such that the first outer layer of the sleeve  208  fits over the stent  208 . 
     The sleeve length  212  ranges from about one foot to about five feet. The typical length of the sleeve  208  is about 1.5 feet from the anchor (barbs  210 ) in the pyloric region of the stomach to below the ligament of Treitz  118  ( FIG. 1 ). The length  212  of the sleeve  202  is selected to bypass the duodenum  104  ( FIG. 1 ) and a portion of the jejunum. The length is increased to further decrease absorption by bypassing a longer section of the jejunum  106  ( FIG. 1 ). The length  212  of the sleeve  202  is variable and dependent on the patient&#39;s Body Mass Index (BMI). The procedure is a less invasive alternative to surgery for the treatment of obesity and morbid obesity and also provides a new treatment approach for type 2 diabetes. 
     The covered stent  208  can be collapsed into a sheath having a diameter less than ¼ inch to enable endoscopic delivery. Covering the exterior surface of the stent  208  with the first outer layer of the sleeve  202  permits endoscopic removal of the implant device  200  by preventing tissue in-growth on the exterior surface of the stent  208 . 
     Markings can be added to the exterior surface of the sleeve  202  to detect the position and orientation of the sleeve on a fluoroscopic image and whether the sleeve is twisted. For example, a stripe can be painted down the length of the device  200  using tantulum impregnated ink, or tantulum bands can be bonded to the exterior surface of the device. If the sleeve  202  is twisted, the sleeve  202  can be untwisted by inserting a balloon into the proximal end of the device thereby sealing it, and then injecting water into the sleeve at low pressure. 
       FIG. 3A  is a plan view of the proximal portion of the gastrointestinal implant device shown in  FIG. 2 .  FIG. 3B  is a cross-sectional view as taken along line AA of  FIG. 3A  showing the stent  208  and the first outer layer  300  and the second inner layer  302  of the sleeve  202  shown in  FIG. 2 . As described in conjunction with  FIG. 2 , the sleeve  202  includes a first outer layer  300  and a second inner layer  302 . The first outer layer  300  is bonded to the second inner layer  300  at positions  306  below the distal end of the stent  208  and at positions  308 , above the proximal end of the stent  208 . A passageway  304  inside the second inner layer  302  of the sleeve  202  allows passage of chyme through the sleeve  202 . The stent  208  is sandwiched between the first outer layer  300  and the second inner layer  302  at the proximal end of the sleeve  202  and is free to move at the distal end within the first outer layer  300  and the second inner layer  302  of the sleeve  202 . The covered exterior surface of the stent  208  prevents tissue growth to allow removal of the implant device  200 . The covered interior surface of the stent  208  provides a smooth passageway for chyme to bypass the duodenum  104 . 
       FIG. 4  is a perspective view of the gastrointestinal implant device  200  with the first outer layer  300  of the sleeve  202  removed. The interconnecting struts which form the mesh (a network of struts) with diamond spaced openings are sufficiently flexible to allow the stent to be collapsed inside a delivery catheter and have sufficient elasticity to hold the pylorus open once the catheter is withdrawn. The force needed to hold the pylorus open is about 1-2 lbs. of radial force outward when the stent is compressed from its full diameter by 25%. 
       FIG. 5  is a sectional view of a body showing the gastrointestinal implant device  200  implanted in the digestive system. The first proximal end  204  of the implant device  200  is anchored to muscle in the pyloric portion of the stomach  102 . The barbs  210  grip onto the muscle to anchor the implant device  200  in place so that the implant device  200  can not be dragged into the stomach or down into the intestines with movement of the stomach and the intestines. 
     The sleeve  202  extends over the ligament of Treitz  118  beyond the proximal jejunum. Extending the sleeve below the ligament of Treitz reduces the likelihood that the sleeve will move back through the duodenum  104  toward the stomach  102 . 
     After the gastrointestinal implant device  200  has been placed in the body and anchored in the pyloric portion of the stomach, chyme leaving the stomach passes through passageway  304  ( FIG. 3B ) inside the sleeve  202  and bypasses the duodenum and proximal jejunum. By directing the chyme through the sleeve  202  the digestion and the absorption process in the duodenum is interrupted. By interrupting mixing of the chyme with juices in the duodenum, partially digested food material is not broken down into particles small enough to be absorbed by the body. Further, there is no mixing of bile with the chyme until the chyme reaches the jejunum. The absorption of fats and carbohydrates is reduced by delaying the mixing of bile with the chyme. 
     The pyloric valve opens periodically to allow chyme to exit the stomach  102  to the duodenum  104 . In one embodiment of the invention the length of the stent  208  is selected to keep the pyloric valve permanently open to induce “dumping syndrome”. By keeping the pylorus open, the chyme empties rapidly into the sleeve  202  and passes down through the sleeve and into the jejunum with minimal digestion. This results in a “dumping syndrome” which is a reaction to excessive rapid dumping of chyme into the jejunum causing the patient to feel ill, dizzy and nauseated. This syndrome is particularly enhanced when sugars and carbohydrates are eaten and passed directly into the jejunum. 
     To hold the pyloric valve open, the length of the stent should be at least 1.5 inches so that the stent extends from the anchoring position in the pyloric portion of the stomach through the pyloric orifice  108  (the opening from the stomach while the pyloric valve is open). The length of the stent is selected so that the distal end of the stent is above the papilla of vater  114  ( FIG. 1 ). As shown, the stent  208  extends through the pyloric orifice  108  to hold the pyloric valve permanently open. In an alternative embodiment, the length of the stent  208  is selected such that the stent  208  ends at the stomach side of the pyloric orifice  108  allowing the pyloric valve to operate normally. 
     The sleeve  202  provides weight loss mechanisms by providing negative feedback, reduced fat digestion and reduced desire for food. The reduced fat digestion occurs because the sleeve  202  delays the mixing of bile and pancreatic juices with chyme from the stomach until after the chyme leaves the sleeve. The reduced desire for food may occur because the sleeve  202  blocks hormonal release from the duodenum. 
     After the chyme from the stomach has passed through the sleeve, the sleeve becomes extremely thin and floppy, permitting the sleeve to contour to the inner walls of the intestine. The sleeve is non-compliant and drapes away from the intestinal walls thereby permitting the pancreatic juice to flow unimpeded into the duodenum through the papilla of vater. The normal peristalsis of the bowel is used to propel the chyme through the intestines. 
       FIG. 6  is a perspective view of a collapsible self-expanding stent  600  in the gastrointestinal implant device  200  shown in  FIG. 2  when expanded. The stent  600  is non-woven, collapsible and self-expanding, allowing endoscopic insertion and removal of the implant device  200 . The stent  600  includes a plurality of flat struts  602  forming an open space pattern to ease collapsing while ensuring self-expansion. The open space pattern allows for collapsing into a catheter for endoscopic delivery and removal. The struts  602  may be manufactured from heat-treated spring steel such as Nitinol or MP35N. 
     In the embodiment shown, the stent has a length L of about 1.5 inches and has a diameter D of about 1 inch. The struts  602  are flat, about 0.010 inches wide and about 0.004 to 0.010 inches thick. The stent can be formed from a tube of material by laser cutting followed by expansion and heat setting, or other methods well known to those skilled in the art. 
     In an alternate embodiment, the struts  602  can be formed separately and the strut intersections can be welded or attached by other means well known to those skilled in the art. Visually the struts form sections  604  around the circumference of the stent. Each section has a series of triangles with each triangle defined by one distal strut connection  606  and two proximal strut connections  608 ,  610 . The ratio of the collapsed diameter to the expanded diameter of the stent is roughly 1:4. 
     When expanded, the angle α between divergent strut sections is about 45-50 degrees and the diameter of the stent is about one inch. When compressed, the angleβ between divergent strut sections is about 5-6 degrees to reduce the diameter of the stent to about 0.21 inch for endoscopic delivery and removal. The elasticity of the struts permits this compression. When the radial compression is released, the elasticity of the struts causes the stent to expand to diameter D. The stent assumes its desired diameter as the elastic restoring forces seek their minimum stress. 
     The ends of the struts at the proximal end of the stent  600  are elongated and shaped to provide barbs  612  to anchor to the muscle in the pyloric portion of the stomach  102 . 
       FIG. 7  is a perspective view of the stent  600  shown in  FIG. 6  when compressed. The stent  600  is compressed until the angle between divergent strut sections is about 5-6 degrees to reduce the diameter D of the stent  600  to about 0.21 inch for endoscopic delivery and removal. The barbs  704  at the proximal end of the stent are elongated. The barbs  704  can be shaped to anchor the stent to the muscular pylorus. 
       FIG. 8  is a perspective view of another embodiment of a stent  800  when compressed. Pairs of barbs  802  at the proximal end of the stent  800  are elongated and can be shaped to provide opposed barbs to anchor the stent  800  in the muscle of the pylorus. 
       FIG. 9  is a perspective view of the compressed stent  800  shown in  FIG. 8  with the strut ends  902 ,  900  bent to provide opposed barbs  904 ,  906 . The barbs  904 , 906  engage the muscle of the pylorus to anchor the gastrointestinal implant device in the pylorus portion of the stomach. As shown in  FIG. 2 , the strut ends  900 ,  902  protrude outward from the outer surface of the stent  800  in opposite directions. They may be perpendicular to each other. The barbs  904 ,  906  at the ends of the respective opposed strut ends  900 ,  902  dig into the pylorus muscle to anchor the stent. The barbs  904 ,  906  at the end of the protruding opposed strut ends  900 ,  902  prevent movement of the stent  800  in either direction; that is, they prevent movement of the stent  800  into the stomach and prevent movement of the stent  800  down through the duodenum. 
       FIG. 10  is a perspective view of the stent  800  shown in  FIG. 8  when expanded. As discussed in conjunction with  FIG. 9 , the opposed strut ends  904 ,  906  engage the muscle of the pylorus while the stent  800  is expanded. In the engaged position, the barbs  904 ,  906  spread radially outward from the longitudinal axis of the stent  800  such that the tips of the barbs come into contact and engage the tissue. 
       FIG. 11  illustrates the gastrointestinal device  1100  shown in  FIG. 1  including an anti-buckling mechanism  1102 . A flexible, anti-rotation, anti-buckling mechanism  1102  is attached to the sleeve  202  and extends from below the distal end of the stent along the length L of the sleeve to the distal end of the sleeve  202 . In the embodiment shown, the anti-buckling mechanism  1102  is a guidewire device attached to the exterior surface of the outer layer of the flexible sleeve. Guidewire devices are well known to those skilled in the art. A first proximal end of the guidewire device  1104  is attached below the stent and a second distal end of the guidewire device  1106  is attached to the distal end of the flexible sleeve. The diameter of the guidewire ranges from about 0.010″ to about 0.016″. 
     The gastrointestinal implant device  200  is designed for endoscopic placement.  FIG. 12  is a perspective view of a portion of a catheter system  1200  for delivery of the gastrointestinal implant device. The catheter system follows a guide wire  1212  through the esophagus and the stomach to the pylorus portion of the stomach. The guide wire  1212  enters a first inner lumen at the proximal end  1208  of the catheter system  1200  and exits the first inner lumen at the distal end  1222  of the catheter system  1200 . 
     The catheter system  1200  includes an outer sheath  1202  for storing the stent  208  in collapsed form, a flange  1216  to pull back the outer sheath  1202  and a sleeve retention wire mechanism  1224  for releasing a sleeve retention wire  1210  from the proximal end of the flexible sleeve  202  after the stent has been released from the outer sheath  1202 . 
     As described in conjunction with  FIG. 2 , the distal portion of the gastrointestinal implant device includes a flexible sleeve  202  which can negotiate the duodenum and the jejunum. A sleeve retention wire  1210  travels through a second inner lumen and exits the second inner lumen to secure the distal end of the sleeve  202  to an inner sheath  1226 . The sleeve retention wire  1210  is coupled to the sleeve retention wire release mechanism  1224  for releasing the sleeve retention wire  1210  after the gastrointestinal implant device has been positioned in the pyloric section of the stomach. The release mechanism  1224  will be described later in conjunction with  FIG. 16B . 
     The sleeve  202  is secured temporarily outside the inner sheath  1226  allowing for proper positioning of the gastrointestinal implant device and then for release. As shown, the sleeve  202  is secured by the sleeve retention wire  1210  using a dead-bolt mechanism  1206 . Non-stick coatings such as Teflon on the sleeve retention wire  1210  are preferred to make release easier to accommodate tortuous anatomical pathways. The sleeve retention wire  1210  extends through the second inner lumen from the release mechanism  1224  of the catheter system  1200  to the dead-bolt mechanism  1206 . The dead-bolt mechanism  1206  is described later in conjunction with  FIG. 14A . 
     The sleeve retention wire  1210  holds the sleeve in position. The distal end of the folded sleeve is released by the release mechanism  1224  by pulling the sleeve retention wire  1210  backward from the proximal end  1208  of the catheter. 
     As described in conjunction with  FIG. 2 , the proximal portion of the gastrointestinal device includes a covered stent. The covered stent does not enter the duodenum and thus is stiffer than the sleeve because it remains in the pylorus of the stomach. The stent in the gastrointestinal implant device is collapsed and stored in the outer lumen within the outer sheath  1202  between the flange  1216  and the proximal end  1208  of the outer sheath  1202 . The stent is supported in a collapsed form by the outer sheath  1202 . The catheter  1200  is inserted into the digestive system through the esophagus to the pyloric section of the stomach. The proximal end of the outer sheath  1202  is positioned in the stomach, in the pylorus through the use of positioning ring  1240 . After the outer sheath  1202  has been positioned, the stent is retracted from the outer lumen of the catheter by pulling flange  1216  toward the proximal end of the catheter system  1200 . Upon release, the stent self-expands by its own elastic restoring force to engage the anchor portion with the stomach muscle at the pyloric section of the stomach. 
       FIG. 13  is a cross-sectional view of the inner shaft  1226  taken along line E-E of  FIG. 12 . The sleeve retention wire  1210  passes through a second inner lumen  1314  in the inner sheath  1226 . The sleeve retention wire  1210  exits the second inner lumen  1314  and is threaded through folds of the sleeve  202  at  1302  in  FIG. 14A . The sleeve retention wire  1210  re-enters the second inner lumen  1314  at  1302  ( FIG. 14A ). The guidewire  1212  passes through the first inner lumen  1310 . 
       FIG. 14A  is an expanded perspective view of the dead-bolt mechanism  1206  shown in  FIG. 12 . The sleeve  202  has been folded for delivery. The sleeve is wrapped around the inner sheath  1226  and bunched above the inner sheath  1226 . The sleeve is held in folded position around the inner sheath  1226  by threading the sleeve retention wire  1210  through the folds of the sleeve  202 . The sleeve retention wire  1210  exits the second inner lumen  1314  through an opening  1304  and pierces through folds of the sleeve  202  at  1304 . Threading the sleeve retention wire  1210  through the folds of the sleeve  202  results in a plurality of small holes at the distal end of the sleeve  202 . The holes are reinforced with silicone or urethane to avoid tears in the material. The sleeve retention wire  1210  re-enters the second inner lumen through a second hole  1302  and advances a sufficient distance within the second inner lumen toward the distal end of the second inner lumen to resist pulling out of the second inner lumen. 
       FIG. 14B  is a sectional view of the dead-bolt mechanism  1206  shown in  FIG. 14A  illustrating the sleeve retention wire  1210  threaded through the sleeve. The sleeve retention wire  1210  exits the second inner lumen at  1306  and pierces through folds in the sleeve  202  at  104 . The sleeve retention wire  1210  re-enters the second inner lumen at  1302 . 
       FIG. 15  is a sectional view of a portion of the catheter system shown in  FIG. 12  illustrating the collapsed stent  208  stored inside the outer sheath  1202 . The stent  208  is pre-compressed and held in a collapsed form inside the outer sheath  1202  of the catheter. The outer sheath  1202  is pulled back by the flange  1216  toward the proximal end of the catheter system  1200  to release the self-expanding stent  208 . The stent radially expands under its own elastic restoring force. The guidewire  1212  is directed through the first inner lumen and the sleeve retention wire  1210  is directed through the second inner lumen in the inner sheath  1226 . The inner sheath includes a first lumen through which the guidewire passes and a second lumen through which the sleeve retention wire passes. 
       FIGS. 16A-C  illustrate a method for delivery of the gastrointestinal implant device.  FIG. 16A  is a plan view of the catheter system illustrating the collapsed stent stored inside the outer sheath  1202  of the gastrointestinal implant device. As described in conjunction with  FIG. 12 , the stent  202  is stored inside the outer sheath and the distal end of the sleeve  202  is secured outside the inner sheath  1226  by a sleeve retention wire  1210 . 
       FIG. 16B  is a plan view of the catheter system illustrating the gastrointestinal implant device after release of the stent from the outer sheath. The flange  1216  has been pulled back toward the proximal end of the catheter system  1200  to pull back the outer sheath  1202  from the stent and the stent  208  has self-expanded. The sleeve retention wire  1210  holds the distal end of the sleeve  202 . 
     Once in place, the sleeve retention wire  1210  can be removed. As described previously in conjunction with  FIG. 12 , the sleeve retention  1210  is coupled to locking mechanism  1224 . Handle  1600  in the locking mechanism  1224  acts as a pivot device to pull the sleeve retention wire  1210  from the dead-bolt mechanism  1206 . The distal end of the gastrointestinal implant device is released by moving handle  1600  in a clockwise direction  1604 . As the handle  1600  is moved in direction  1604 , the sleeve retention wire  1210  threaded through the folds of the sleeve is pulled back through the second inner lumen  1314  and disengages from the sleeve at the distal end of the gastrointestinal implant device. The sleeve retention wire  1206  extends from the distal end of the gastrointestinal implant device through the second inner lumen  1314 . The wire is connected to the handle  1600  at the proximal end of the catheter. 
       FIG. 16C  is a plan view of the catheter system illustrating the expanded gastrointestinal implant device after the sleeve retention wire has been released. The handle  1600  has been moved in a clockwise direction and the sleeve retention wire  1210  pulled back through the second inner lumen  1314  to release the distal end of the sleeve  202 . 
       FIG. 17  is a perspective view of another embodiment of the catheter system shown in  FIG. 16 . The catheter includes a ball  1800  coupled to the distal end  1222  of the inner sheath  1226  for guiding the catheter through the alimentary canal to the pyloric portion of the stomach. The ball  1800  is small enough so that it can be pulled back through the gastrointestinal implant device after the gastrointestinal device has been delivered, the stent expanded and the sleeve retention wire  1210  has been released. The sleeve is shown uniformly folded. However, the sleeve may not necessarily be uniformly folded. 
       FIG. 18  is a cross-section of an everting catheter system  1900  for delivery of a longer flexible sleeve. The gastrointestinal implant device  200  is shown with the stent sleeve anchor  1901  and the attached sleeve  1902  shown as delivered into the anatomy. The delivery catheter previously described is then removed. A balloon catheter  1906  is introduced into the stent sleeve anchor  1901  and the balloon  1908  inflated to seal the lumen of the stent  1901 . The sleeve  1902  is folded inside itself and an elastic band  1912  is used to seal the end of the sleeve. Fluid is then injected through the balloon catheter shaft  1906  into the sleeve lumen  1910 , filling the lumen and pressurizing it. The pressure of the fluid is used to push the inner sleeve distally towards  1904 . When the sleeve  1902  has fully deployed distally, the elastic band  1912  falls off of the closed end of the sleeve  1902  and passes distally in the intestine until it is excreted. This mechanism permits deployment of a sleeve that is double the length of the delivered device. This may be needed as it is difficult to access the distal parts of the intestine with guidewires. This everting catheter system enables delivery of longer sleeves than are possible using only the delivery catheter described in conjunction with  FIG. 12 . 
       FIG. 19  is a perspective view of a retrieval device  2000  for removing the gastrointestinal implant device  200  from the digestive tract. As already described, the exterior surface of the stent  208  is covered with a material that prevents cellular in-growth allowing the stent  208  to be easily removed. The retrieval device  2000  includes an inner sheath  2004  and an outer sheath  2006 . A plurality of fingers  2002  extend from the proximal end of the inner sheath  2004 . The fingers  2002  engage the exterior surface of the gastrointestinal device. As the inner sheath  2004  is moved down over the fingers, the fingers  2002  pull radially inward to reduce the proximal stent diameter and pull the collapsed device into the outer sheath  2006 . 
       FIG. 20  is a perspective view of the retrieval device  2000  engaged with the stent  208 . The fingers  2002  of the retrieval device are positioned around the stent  208 . As the inner sheath  2004  is pushed over the fingers  2002 , the fingers pull radially inward on the proximal end of the stent  208  and the proximal end of the stent  208  is collapsed. After the stent  208  has been collapsed sufficiently such that the proximal stent diameter is less than the diameter of the outer sheath  2006 , the stent is drawn into the outer sheath  2006 . The entire gastrointestinal implant device can then easily be removed from the patient by pulling retrieval device  2000  through the stomach and the esophagus. 
       FIG. 21  is a perspective view of another embodiment of a gastrointestinal implant device  2200 . The gastrointestinal implant device  2200  includes a sleeve  202  and an anchoring ring  2204 . The distal end of the anchoring ring  2204  is bonded to the proximal end of the sleeve  202 . A plurality of eyelets  2206  are distributed around the circumference of the proximal end of the ring for anchoring the device to the pyloric muscle using anchors shown in  FIG. 24 . The anchoring ring  2204  is made from a flexible material such as silicone allowing the ring  2204  to be collapsed for endoscopic insertion and removal. 
     The anchoring ring  2204  does not hold the pylorus open. However, in an alternate embodiment, the anchoring ring  2204  can be bonded to a stent with sufficient length and diameter to hold the pylorus open as described in conjunction with  FIG. 2 . The anchoring ring  2204  anchors the device and the stent holds the pylorus open. 
       FIG. 22  is a perspective view of the anchoring ring  2204  shown in  FIG. 21  in the expanded position. The sleeve is bonded to the outer surface  2300  of the proximal end of the anchoring ring whose diameter is 0.8″ or about the same as the diameter of the sleeve. The anchoring ring  2204  includes at least four eyelets to anchor the device in place. The outer most diameter of the ring is about one inch. In an alternate embodiment there can be more than four eyelets. 
       FIG. 23  is a perspective view of the anchoring ring  2204  shown in  FIG. 21  in a collapsed position for insertion and removal. The circular ring  2204  shown in  FIG. 21  has been compressed to an oval shape allowing the anchoring ring to be inserted into the lumen of a catheter for delivery. 
       FIG. 24  is a perspective view of an anchor  2500  for anchoring the collapsible ring shown in  FIG. 23  to the muscular tissue of the pyloric orifice. The anchor  2500  includes an anchor pin  2504  coupled to a second pin  2506  by a flexible shaft  2502 . The anchor pin  2504  includes a shaped barb  2508  for locking the anchor  2500  into the tissue. The anchor  2500  is delivered after the collapsible ring has been positioned in the pyloric orifice. The anchor is guided so that the anchor pin  2504  is directed through a respective eyelet with the barbed portion of the anchor pin  2504  guided toward the tissue. After the barb  2508  has been locked into the tissue, the second pin  2506  sits inside the gastrointestinal implant device while the barbed portion  2508  of the anchor pin  2504  sits inside the pylorus muscle tissue. For removal of the gastrointestinal implant device from the body, the flexible shaft  2502  of the anchor  2500  is cut. 
       FIG. 25A  is a perspective view of a delivery system  2600  for delivering the anchor  2500  after the gastrointestinal implant device has been placed in the pyloric orifice. The anchor  2500  is loaded in the distal end of a catheter having a single lumen tube  2600 . The hollow, distal end of the delivery device is a sharp needle made to penetrate the pylorus muscle. In an alternate embodiment, the distal end of the delivery device can be formed in an arc to improve access to the eyelets through an endoscopic approach. The catheter  2600  includes a pusher  2604  for releasing the anchor  2500 . The pusher  2504  is moved in a longitudinal direction  2602  to release the anchor  2500  from the lumen. 
       FIG. 25B  is a plan view of the delivery system  2600  shown in  FIG. 25A .  FIG. 25C  is a cross-sectional view of the distal end of the catheter  2600  as taken along line B-B of  FIG. 25B . As described in conjunction with  FIG. 24 , the anchor  2500  includes pins  2504 ,  2506  coupled by a flexible shaft  2502 . The anchor  2500  is loaded in the lumen at the distal end of the catheter  2600 . The anchor pin  2504  is placed in the distal end of the tube  2600  and the second pin  2506  in the proximal end. The barb  2508  on the anchor pin  2504  is pointed toward the proximal end of the tube  2506  to engage with the tissue upon release in the muscle tissue. The catheter is advanced to the center of the ring positioned in the pyloric orifice. The sharp end  2510  is then pushed through an eyelet and into the muscle tissue. The pusher  2506  is pushed in longitudinal direction  2602  to release the distal anchor  2506 . Once the distal anchor is released, the delivery system is pulled back, dragging the proximal part of the anchor out of the delivery device with the flexible shaft going through the eyelet, and the proximal anchor portion resting on the inside of the device. In the embodiment of the ring shown in  FIG. 22 , four anchors  2506  are delivered to anchor the gastrointestinal implant device through the four eyelets. 
       FIG. 25D  is an isometric view illustrating the sharp end  2510  of the needle inserted through an eyelet  2206  for delivery of the anchor  2500  to the tissue  2512 . The distal end of the catheter is formed in an arc  2520  to improve access the eyelets  2206 . The sharp end  2510  of the catheter is inserted through the eyelet  2206  into the tissue  2516 . The anchor pin  2504  of the anchor has been pushed out from the lumen into the tissue  2512 . 
       FIG. 25E  is an isometric view illustrating the barb  2508  engaging the tissue  2512  after delivery. The catheter has been removed from the eyelet  2206  leaving the anchor pin  2504  engaging the tissue  2516 . 
       FIGS. 26A-E  illustrate an alternative embodiment of a locking mechanism for holding the distal end of the sleeve  202  in position during delivery of the gastrointestinal implant device. The snare wire  2650  is passed through one of the lumens of the catheter to the distal end. At the distal end, the end of the snare wire  2650  is looped back and attached to or anchored inside the catheter. The folds of the sleeve  202  are advanced through this snare loop. The snare handle  2664  pulls and releases the snare wire  2656  to lock and release the distal end of the sleeve  202 . The delivery system includes a pull tap  2666  for releasing a drawstring holding the stent in a collapsed position. 
       FIG. 26B  is cross-sectional view taken along line C-C of  FIG. 26A  through the inner sheath  2650 . The inner sheath has two lumens  2654 ,  2656  and has a diameter of about 0.078 inches. The first inner lumen  2564  is for passing a guidewire through the inner sheath and is about 0.04 inches in diameter. The second inner lumen  2656  is for passing the snare wire through the inner sheath is about 0.02 inches in diameter. The end of the snare wire  2658  is anchored inside the inner sheath. 
       FIG. 26C  is a cross-sectional view taken along line DD of  FIG. 26A  through the outer sheath  2600  showing the inner sheath within the outer sheath. The outer sheath has an inner diameter of about 0.1 inches and an outer diameter of about 0.143 inches. The open space inside the outer sheath can be used for passing a drawstring through the outer sheath. 
       FIG. 26D  is a cross-sectional view through the distal portion of the catheter showing the snare capturing the distal end of the sleeve. The distal end of the sleeve  202  is captured by the snare wire  2656  by pulling the distal end of the sleeve through a loop formed by the snare wire  2656 . 
       FIG. 26E  is a sectional view through the distal portion of the catheter showing the snare locking mechanism. The distal end of the sleeve is locked by pulling the snare wire  2656  in a longitudinal direction  2664  toward the proximal end of the delivery system to capture the sleeve folds against the inner shaft. After the gastrointestinal implant device is properly positioned in the body, the snare wire is advanced in a longitudinal direction  2662  toward the distal end of the delivery system. This opens the snare wire  2656  and releases the sleeve  202 . 
       FIG. 27  is a perspective view of the distal portion of the gastrointestinal implant device including texturing  2700 . Texturing of the distal end of the sleeve can be added to ensure that the actions of peristalsis do not advance the sleeve proximally, towards the stomach, but keep the sleeve pulled taught in the intestine. At the distal end of the sleeve, texturing  2700  is added with a directional aspect to it. The texturing  2700  can be molded into the sleeve material or added by adhesive or thermal bonding methods. The texturing material includes fibril shapes that are directed proximally so that any peristaltic waves that travel proximally will have less force on the sleeve than distal peristaltic waves. 
     The gastrointestinal implant device offers a new alternative where other means of weight loss and efforts at behavior modification have failed. Because the gastrointestinal implant device is endoscopically introduced, there is a reduced risk at insertion compared to surgery. The procedure is also completely reversible, making this approach the ideal solution for patients who are desperate to reverse behavioral patterns that have led to weight gain. 
     When inserted in the body, the gastrointestinal implant device mimics the duodenal bypass of the Roux-en-Y procedure. The implanted device reduces caloric absorption by delaying enzyme mixing with food and provides the feedback produced by the Roux-en-Y procedure by producing dumping syndrome when high sugar meals are ingested. Rapid stomach emptying is encouraged by inserting a stent in the pylorus to hold the pylorus open and all food bypasses the duodenum and passes rapidly into the jejunum. The implant device is an improvement on the Roux-en-Y procedure because it is minimally invasive and reversible. In the treatment of the super-obese where aggressive weight loss is not achieved, the length of the implant device below the stent can be further increased to drive the patient close to the point of malabsorption. 
     Placement of the gastrointestinal implant device effectively provides that ingested food does not digest in a normal manner and the gut hormones that are normally triggered are modified. These hormones result in several physiology changes that impact hunger and digestion. Gut hormones include peptide YY (PYY), cholecystokinin (CCK) and ghrelin. 
     As under digested food enters the ileum or distal part of the small intestine, a hormone called peptide YY or PYY is released. This hormone has been shown to have a direct effect on appetite, reducing it when released. Undigested food in the ileum indicates that too much food has been ingested. Thus, dependent on the length of the sleeve, the gastrointestinal device can promote deposition of undigested or partially digested food to the distal bowel. Therefore, the placement of a sleeve in the intestine promotes the delivery of undigested food to the ileum, which in turn promotes the release of PYY and reduces appetite in humans. 
     The hormone cholecystokinin (CCK) is released when food contacts the duodenum. CCK triggers the release of bile from the gallbladder. Therefore, placing a sleeve in the duodenum reduces the release of CCK and thus reduces bile output resulting in reduction in the digestion of food. 
     Some ghrelin is released when food contacts the duodenum. Ghrelin has been shown to be a factor in the control of appetite. This device will reduce ghrelin output and thereby reduce appetite due to the bypass of the duodenum. 
     Type 2 diabetes is a disease of obesity that occurs when patients cannot adequately use the insulin they produce. Usually, it is not that the patient cannot make enough insulin, but rather that the patient&#39;s body cannot effectively use the insulin produced. A particularly dangerous result of type 2 diabetes is that blood sugar spikes after a meal. This is called post-prandial hyperglycemia. This spike in blood glucose causes cardiovascular and microvascular damage. One class of drugs used to control post-prandial hyperglycemia is the alpha-glucosidase inhibitors. These work by reducing the breakdown and absorption of carbohydrates to sugars. The sleeve has a similar function because it reduces bile and delays the breakdown and absorption of the carbohydrates, which are normally readily absorbed in the duodenum, but are less likely to be absorbed in the jejunum and ileum. Therefore, type 2 diabetes can be controlled by placing a sleeve in the proximal intestine to delay the digestion of carbohydrates which reduces post-prandial hyperglycemia. 
     The gastrointestinal implant device can be used to reduce Type 2 diabetes symptoms by bypassing the duodenum. Following gastric bypass surgery, patients commonly experience complete reversal of Type 2 diabetes. While the exact mechanism of this remarkable effect is not understood, the clinical result is reported in a high percentage of cases. Reversal of Type 2 diabetes after gastric bypass is described in “Potential of Surgery for Curing Type 2 Diabetes Mellitus” by Rubino et al. incorporated herein by reference in its entirety. Since the gastrointestinal implant device provides equivalent blockage of duodenal processes, a similar effect is elicited but without the trauma of surgery. In patients who are not obese but suffer Type 2 diabetes, a modified gastrointestinal implant device is inserted. This gastrointestinal implant device provides the necessary effect to hinder pancreatic processes and receptors without blocking absorption. 
     In the embodiment of the gastrointestinal implant device for treating diabetes, the length of the stent may be selected to allow the pylorus to operate normally. The length of the sleeve may be reduced to mimic the duodenum bypass. The sleeve extends to just below the ligament of Treitz but does not extend further into the jejunum, thus allowing absorption to occur in the jejunum. 
     The gastrointestinal implant device can be placed temporarily in the stomach and duodenum to allow tissues to heal. For example, the sleeve can be placed temporarily to promote healing of ulcers in the stomach and duodenum. Ulcers are lesions that form in tissues of the stomach and duodenum. If they bleed, they are typically cauterized with electrosurgery. For ulcers to heal, they must be protected from the acidic environment. Placement of a sleeve for a short time period, for example, for one to two weeks, promotes healing of ulcers in the stomach and duodenum by eliminating the acidic environment and allows the tissues to heal. 
     Intestinal anastomoses are performed to remove sections of diseased bowel. The stapled or sewn connection is prone to leakage until it heals. The placement of the gastrointestinal implant device temporarily in the bowel can be used to promote healing of small bowel anastomoses by protecting the area from chyme and minimizing leaks. 
     The gastrointestinal implant device can be used to deliver drugs, hormones and other active agents directly to the intestine. To deliver the agents, the sleeve is either coated or impregnated with the agents. 
     The two most common intestinal bowel diseases are Crohn&#39;s disease and ulcerative colitis. Crohn&#39;s disease may occur in any part of the digestive tract. Although the exact cause of the disease is unknown, it appears to be an abnormal immune response in the patient, which leads to chronic inflammation of the intestinal lining. 
     Crohn&#39;s disease is treated with drugs intended to reduce inflammation. These include aminosalicylates, corticosteroids, immune modifiers such as azathioprine and methotrexate and antibiotics including ampicillin and cipro. These drugs have negative effects when given systemically. Since the drug is really only needed locally, smaller amounts of drug can be used if delivered directly to the tissues. 
     The intestinal sleeve is coated with polymers that are impregnated with these drugs. Coatings may include polyurethanes, silicones and hydrophilic polymers like Hydromer. These coatings may be applied to the sleeve material by dipping or spraying techniques. If a porous sleeve material such as ePTFE is used, the drug filled polymer may be driven into the pores using internal pressure inside the sleeve. This increases the amount of drug that is available. 
     The sleeve material can also be a polymer that permits the incorporation of the drug directly into the wall. Such polymers include Ethylene Vinyl Acetate (EVA) and polyurethane. A greater amount of the drug may be incorporated in this case compared to a coating since there is more material in the wall than simply in coatings, thereby providing longer release times. The drug is compounded into the polymer and then extruded as is normally done to form the tubing or sheet from which the sleeve is made. 
     The sleeve is deployed transesophageally into the duodenum and proximal jejunum. When the sleeve comes in contact with the tissues, the drugs in the coating are released directly into the tissues. Also, the sleeve may act to block the contact of the food to the mucosa, thereby reducing irritation caused by the chyme. Once the drug has fully eluted from the material, the sleeve is removed and a new one is placed. 
     The control of appetite in the human is a complex function of hormonal interactions. Several hormones have been implicated in its control including Ghrelin, PeptideYY, Leptin, Glucagon-Like Peptide-1 (GLP-1), Cholecystokinin (CCK), insulin and others. These hormones are either released or suppressed by the presence of food in the duodenum. For example, PYY acts as an anti-hunger hormone as injections of PYY have been shown to decrease food intake in both rats and humans and decreases in leptin have been shown to stimulate hunger. 
     Sleeves that are located in the duodenum where many of these hormones are released may be impregnated with these hormones. When implanted, the hormones elute from the sleeve into the surrounding tissue where they activate the various satiety mechanisms. 
       FIG. 28  is a perspective view of a gastrointestinal implant device with another embodiment of a collapsible self-expanding anchoring device. The gastrointestinal implant device  2800  includes a sleeve  202  and an anchoring device for anchoring the gastrointestinal implant device in the pylorus. The anchoring device includes two rings  2803 ,  2802  of differing diameters. A portion  2806  has been cut off to show the rings  2803 ,  2802 . The rings are made from a metal such as heat treated spring steel. In one embodiment the rings are made from Nitinol. 
     The rings are spaced apart and are covered by the sleeve  202 . The distal end of the proximal ring  2803  is bonded to the proximal end of the sleeve  202 . The distal ring  2802  is also bonded to the sleeve distal to the proximal ring. The rings are spaced apart such that when the gastrointestinal device is positioned in the body, the proximal ring is located in the stomach and the distal ring is located in the duodenum. 
     The proximal ring  2803  serves to prevent the device from moving in the distal direction  2805  into the duodenum. The distal ring  2802  serves to resist motion in the proximal direction  2804 . The diameter of each of the rings is variable with the diameter of the proximal ring greater than the diameter of the distal ring. In one embodiment, the diameter of the proximal ring  2803  is about 1.4″ (35.6 mm) and the diameter of the distal ring  2802  is about 1.0″ (25.4 mm). The diameters of the rings are dependent on the anatomy. The diameter of the proximal ring  2803  is selected to be greater than the pyloric orifice which is typically about 1″ in diameter to prevent the ring from being pulled through the pyloric orifice to the intestines. The diameter of the distal ring  2802  is selected so that the ring is less than the diameter of the duodenum. The distance between the rings is dependent on the length of the pyloric orifice. This distance is selected so that when the proximal ring  2803  is positioned in the stomach, the distal ring  2802  is positioned at the distal end of the pyloric orifice in the duodenum. The distance between the rings also determines whether the pylorus is held open. If the distance between the rings is equal to the length of the pylorus, the pylorus is held open. If the distance between the rings is greater than the length of the pylorus, the sleeve material between the rings is loose allowing the pylorus to operate normally. 
       FIG. 29  is a plan view of one of the rings  2803  in the gastrointestinal implant device shown in  FIG. 28 . The ring  2803  includes a wire  2906  and a crimp connector  2907 . The ends of the wire  2908 ,  2909  are connected through the crimp connector  2907  to form the ring  2803 . The anchoring device can be collapsed into a sheath to enable endoscopic delivery. 
     The wire is made from a Nitinol material and is heat treated to provide a super elastic state at a range of temperatures from room temperature through body temperature. The wire  2906  is about 0.020″-0.027″ in diameter. The diameter of the wire is selected to provide sufficient radial stiffness to resist collapse by forces in the body, but to permit collapse into a delivery device. 
       FIG. 30  is a perspective view of the anchoring device in the gastrointestinal implant device shown in  FIG. 28  in a collapsed position in a delivery tube  3010  for delivery into the body. The anchoring device is delivered to the stomach by folding each of the rings  2803 ,  2802  in a double U shape to reduce their diameter and length, so that the rings fit inside the delivery tube  3010  for endoscopic delivery and to permit deployment of the rings in a serial manner. 
     The delivery tube  3010  has a diameter of about 0.394″-0.591″ (10-15 mm) and is about 2 inches in length. The rings  2803 ,  2804  are folded such that they fit inside the delivery tube  3010  and do not exceed the elastic limit of Nitinol. The folding into a double U shape also permits the rings  2802 ,  2803  to be pushed out of the delivery tube  3010  in distal direction  2805  in an orderly manner for delivery into the body. After delivery of the gastrointestinal device, the delivery tube  3010  is removed from the body through the stomach in proximal direction  2804 . 
       FIG. 31  is a perspective view of the gastrointestinal device illustrating the deployment of the distal ring from the delivery tube  3010  shown in  FIG. 30 . As described in conjunction with  FIG. 30 , the rings  2803 ,  2302  are folded in a double U shape and are loaded into delivery tube  3010 . A piston  3101  and proximal shaft  3102  are moveable with respect to delivery tube  3010  such that as the delivery tube  3010  is pulled in proximal direction  2804 , or the shaft  3102  is pushed in distal direction  2805 , the distal ring  2803  is first deployed in the duodenum, and then the proximal ring  2802  is deployed proximal in the stomach. 
       FIG. 32  is a perspective view of the gastrointestinal device after the deployment of the distal ring  2803  prior to deployment of the proximal ring  2802 . After deployment, the distal ring  2803  expands under its own elastic force and is positioned in the duodenum. The portion of the sleeve  202  between the rings is then pulled in proximal direction  2804 . As the second proximal ring  2802  is released, it is positioned in the stomach. 
       FIG. 33  is a perspective view of the gastrointestinal implant device shown in  FIG. 28  with an alternative embodiment of an anchoring device. The anchoring device includes two nitinol rings  3300 ,  3302  of differing diameters where the rings are shaped with stabilizing ears  3304  to prevent the rings from twisting. 
     Each of the rings  3300 ,  3302  is fabricated from nitinol wire as previously described. Each ring contains loops (stabilizing ears)  3304  that protrude beyond the diameter of the ring. These loops  3304  serve to provide additional anchoring into the tissues and especially to limit rotation of the rings in place. The addition of the loops to each ring permits reduction of the wire diameter and/or the ring diameter while maintaining similar anchoring ability. This also reduces trauma to the anchoring tissues. The number of loops  3304  is variable. There can be two, three or four loops. In the embodiment shown, each ring has four loops. As the gastrointestinal device is a removable, tissue in-growth into the anchoring device is not desired. Therefore, each loop  3304  is coated with a polymer such as polyurethane in a dipping process to fully cover the openings. 
       FIG. 34  is a plan view of the gastrointestinal implant device shown in  FIG. 33 . The loops on each of the rings protrude through the exterior surface of the sleeve to push against the tissue to anchor the gastrointestinal implant device in the pyloric region of the stomach. The non-loop portions of each of the rings are encapsulated by the sleeve. 
       FIG. 35  is a perspective view of another embodiment of one of the anchoring rings shown in  FIG. 28 . In the embodiment shown, a ring  3500  is formed from multiple wires. In this case, two wire loops  3502 ,  3504  are loosely intertwined to form a single anchoring ring  3500 . By forming the ring from multiple wires, the diameter of the wire can be reduced. Therefore, the rings can be folded into a smaller delivery device and still maintain the same the radial force on the tissue as the single wire embodiment to hold the ring in place when deployed. Additional wires can be used to further reduce the diameter of the wires. Wire  3502  contains loops  3506  that protrude beyond the diameter of the ring  3500  to provide additional anchoring into the tissues. 
       FIG. 36  is a perspective view of a gastrointestinal implant device with yet another embodiment of an anchor. The device includes two nitinol rings of differing diameters that are linked together with connecting rods  3600  to stabilize the rings  2803 ,  2802 . The connecting rods  3660  stabilize the anchor by limiting motion of the rings. 
     The anchor is formed by proximal ring  2803  and distal ring  2802  loosely connected by at least one connecting bar  3600 . There are loops  3602 ,  3604  at the end of each connecting bar  3600 , each loop  3602 ,  3604  engages a respective one of the rings  2803  and  2802 . The sleeve  202  encapsulates the entire assembly. 
       FIG. 37  is a perspective view of the anchor shown in  FIG. 36  with the sleeve  202  removed. There are four interconnecting bars  3600  spaced apart from each other around the diameter of the rings  2803 ,  2802 . The interconnecting bars  3600  serve multiple functions. First, when the anchor is in position in the body with the proximal ring  2803  in the stomach and the distal ring  2802  in the duodenum, the interconnecting bars  3600  serve to stent open the pylorus. Second, the interconnecting bars  3600  serve to stabilize each of the rings  2803 ,  2802  and limit the twisting or translational motion of the rings with respect to each other. 
       FIG. 38  is a perspective view of the anchor shown in  FIG. 37  in a collapsed position in a delivery tube  3010  for delivery into the body. The rings  2803 ,  2804  connected by connecting bars  3600  are folded in a double U shape and placed inside the delivery tube  3010 . As described in conjunction with  FIG. 30 , after delivery of the gastrointestinal device, the delivery tube  3010  is removed from the body through the stomach in proximal direction  2804 . 
       FIG. 39  is a perspective view of the anchor shown in  FIG. 37  illustrating the deployment of the distal ring  2803  from the delivery tube  3010  shown in  FIG. 38 . As described in conjunction with  FIG. 31 , the distal ring  2803  is first deployed distal to the pylorus in the duodenum, and then the proximal ring  2802  is deployed proximal to the pylorus in the stomach. 
       FIG. 40A  is a plan view of the gastrointestinal device shown in  FIG. 38  with additional anti-rotation and locking features. The connecting rods  3600  are further formed with loop extensions  4000 . The loop extensions  4000  on each connecting rod  3600  are angled towards each other. These loop extensions  4000  press against the muscle of the pylorus to anchor the gastrointestinal implant device in the pylorus portion of the stomach and serve to prevent any linear motion of the device. Rotation of the device is also reduced. The loop extensions  4000  are coated with polyurethane to prevent tissue in growth. 
       FIG. 40B  is a perspective view of the anchor shown in  FIG. 40A  without the sleeve. The loop extensions  4000  on a connecting bar  3600  are angled towards each other to prevent linear motion. The loop extensions on the proximal end of the connecting bar  3600  are angled in a distal direction and the loop extensions on the distal end of the connecting bar are angled in a proximal direction. 
       FIG. 41  is a plan view of an alternative embodiment of a gastrointestinal implant device shown in  FIG. 28 . The gastrointestinal device includes two nitinol rings  2802 ,  2803  of differing diameters as described in conjunction with the embodiment described in conjunction with  FIG. 28 . The gastrointestinal implant device has sleeve material  202  on the inside and the sleeve material and rings are coated with a polymer such as polyurethane  4100  on the outside. 
       FIG. 42A  is a perspective view of a portion of a low profile catheter system  4250  for delivery of a gastrointestinal implant device. The low profile catheter has a detachable generally spherical shaped element  4218  coupled to the distal end of an inner shaft  4200  to aid the delivery of the catheter through the alimentary canal to the intestines. After the gastrointestinal implant device has been delivered, the spherical shaped element (ball)  4218  is detached and the zero profile catheter is removed through the gastrointestinal implant device. The normal peristalsis of the bowel is used to move the released ball through the intestines. 
     The catheter system  4250  includes an outer sheath  4222  for storing the collapsible anchor portion of the gastrointestinal implant device in collapsed form. Collapsible anchoring devices have already been described in conjunction with  FIGS. 7, 23 and 30 . The sleeve  202  is secured temporarily outside an inner sheath  4200  allowing for proper positioning of the gastrointestinal implant device and then for release. 
       FIG. 42B  is a cross-sectional view of the inner shaft  4200  of the catheter system as taken along line  42 B- 42 B of  FIG. 42A . In one embodiment, the inner shaft  4200  is a three-lumen extrusion of Pebax 7233 with an outer diameter of 0.080″ and round inner lumens  4202 ,  4204 ,  4206  having respective diameters of 0.040″, 0.020″ and 0.020″. This material is selected to maintain a low profile, a small minimum bend radius; that is less than 0.5″ without kinking, good column strength when fortified with an inner guide wire stylet, and a low coefficient of friction in a material with good thermoplastic and bonding properties. 
     A first lumen  4202  is used to pass a guide wire or mandrel  4226  through the catheter shaft to increase the rigidity of the catheter shaft during introduction of the catheter into the intestines. The first lumen  4202  is also used to inject fluid to lift the sleeve material  202  away from the inner shaft  4200  after the gastrointestinal device has been delivered to the intestine. A second lumen  4204  is used to pass a sleeve retention wire  4208  to the distal end of the gastrointestinal implant device. The sleeve retention wire is used to hold the distal end of the sleeve  202  to the outside of the inner shaft  4200 . A third lumen  4206  is used to inject fluid at the tip of the catheter to lift the distal end of the sleeve  202  off the inner shaft  4200  prior to removal of the catheter system  4250  from the body. 
     Returning to  FIG. 42A , the guide wire  4226  is passed through fitting  4210  connected to the first lumen  4202 . The sleeve  202  is located concentrically over the catheter inner shaft  4200 . It is held at its distal end to the inner shaft  4200  with the sleeve retention wire  4208 . The sleeve retention wire  4208  holds the sleeve  202  in place during delivery. 
     Proximal fitting  4220  is connected to the second lumen and proximal fitting  4212  is connected to the third lumen  4206 . During delivery of the gastrointestinal implant device, the first lumen  4202  is filled with a 0.035″ Teflon coated guide wire  4226  that provides column strength for the appropriate amount of pushability without compromising the flexibility of the catheter inner shaft  4200 . A 0.015″ diameter Teflon-coated steel wire is placed in the second lumen  4204  to serve as the distal sleeve retention wire. The second lumen  4204  has 2 skive holes  4214 ,  4216  near the distal end of the catheter shaft  4200 . The distal sleeve retention wire  4208  exits the second lumen  4204  through a proximal skive hole  4214  feeds through the sleeve material  202 , which is wrapped tightly around the distal outer diameter of the catheter shaft, and re-enters the second lumen  4204  through a distal skive hole  4216 . This creates a dead bolt style lock holding the sleeve  202  to the shaft  4200  until ready to be released similar to the dead bolt style lock described in conjunction with the two lumen catheter shaft shown in  FIGS. 14A and 14B . 
     The distal end of the shaft terminates with a spherical shaped element  4218  that is either solid, or inflatable to form an atraumatic tip. In the embodiment shown, the spherical shaped element is a solid ball, similar to the ball described in conjunction with  FIG. 17 . In the embodiment shown, the diameter of the ball is about 0.5″ (12.7 mm), however the range of diameters is about 0.25″ (6.4 mm) to about 0.75″ (19.2 mm). An embodiment of an inflatable spherical shaped element is described later in conjunction with  FIGS. 50A-50B . The ball  4218  at the end of the catheter shaft is held onto the shaft  4200  with the sleeve retention wire  4208  maintaining tension on the ball  4302  which will be described later in conjunction with  FIG. 46 . 
     The collapsed anchor assembly is located in outer sheath  4222 . The ball  4218  at the end of the catheter is released to withdraw the catheter. The release mechanism pulls the sleeve retention wire to release the ball end and release the end of the sleeve. The anchor assembly is then released from the outer sheath as previously described 
     The catheter can be used any time access to the intestinal tract is desired. For example, the catheter can be used to pass an endoscope into the intestine. This catheter device can be used to rapidly run the intestines, place a guide wire and then use the placed guide wire as a track for an endoscope. 
       FIGS. 43-45  illustrate the steps for delivery of the gastrointestinal implant device using the low profile catheter described in conjunction with  FIGS. 42A-42B .  FIG. 43  is a sectional view of a portion of the digestive tract in a body illustrating the position of a gastroscope/guide tube assembly. 
     The small bowel is accessed endoscopically by passing a semi-rigid tube into the stomach and into the pylorus and proximal duodenum, inflating the bowel with a fluid, preferably water, and then passing a thin, flexible catheter with a large, atraumatic ball tip through the bowel. 
     A guide tube  4300  is placed over the end of a gastroscope  4302 . The guide tube/gastroscope assembly is then placed through the patient&#39;s mouth, down the esophagus and into the stomach  102 . The assembly is then passed into the pylorus  108  and the duodenum  104 . 
     The guide tube  4300  has an inner diameter of approximately 0.63″ (16 mm) and an outer diameter of approximately 0.70″ (18 mm). It is approximately 30″ (76.2 cm) in length and is made of a flexible polymer such as urethane with a flat wire wrap to provide kink resistance and pushability. The distal end of the guide tube  4300  can have a short, flexible end to minimize trauma to the pylorus  108 . 
     Once in place, fluid is introduced through the channel of the gastroscope  4302  to inflate the intestine distally. Saline or water are preferred but air or carbon dioxide (CO 2 ) can also be used. About 500-1000 cc of fluid is introduced for delivery of a 4′ length of sleeve. Shorter sleeves require less fluid because the length of intestine to distend is less. After the fluid is introduced, the gastroscope is removed from the guide tube. 
     If desired, the gastroscope  4302  can be removed from the guide tube  4300  and a balloon catheter can be introduced to deliver the fluid. The balloon catheter is delivered to the pylorus and inflated to roughly 0.394″-0.591″(10-15 mm) to seal the intestine. A balloon catheter has already been described in conjunction with  FIG. 18 . 
       FIG. 44  is a sectional view of a portion of the digestive tract in a body illustrating the distal portion of the catheter assembly extending from the distal portion of the guide tube  4300 . The catheter assembly  4250  is advanced through the guide tube  4300  after the gastroscope  4302  has been removed from the guide tube. The ball  4218  at the end of the catheter assembly  4250  provides an atraumatic, leading tip to the catheter such that the catheter follows the contour of the intestines. 
       FIG. 45  is a sectional view of a portion of the digestive tract in a body after the gastroinstestinal implant device of  FIG. 28  has been delivered. The anchor of the gastrointestinal implant device is located inside the delivery tube  4222 , which is located in the pylorus  108 . A marker on the proximal end of the catheter  4200  aligns with a corresponding marker on the guide tube  4300  when the catheter is fully inserted. Once the gastrointestinal device is in place, the sleeve retention wire  4208  in the catheter  4302  which holds the sleeve  202  in place and also holds the ball  4218  to the distal tip of the catheter can be removed as discussed in conjunction with the catheter system shown in  FIGS. 16A-16C . As the sleeve retention wire is pulled back in a distal direction, both the ball  4400  and the distal end of the sleeve  4500  are released. Fluid is then introduced through the third lumen  4206  in the catheter to open the sleeve  202  and expand the sleeve away from the catheter shaft  4200 . Water or saline are preferred fluids although air or CO 2  can be used. Approximately 100-200 cc is injected. The fluid exits the catheter at a mid point skive hole  4502  and travels in both a distal and proximal direction. Approximately 20 cc of fluid is then injected through the second lumen  4204  and exits the distal skive hole  4216 . This fluid lifts the distal end of the sleeve  202  off the inner catheter shaft  4200 . 
     The guide tube  4300  is then removed and the gastroscope re-introduced into the stomach to view the pylorus  108 . The proximal anchor is then deployed by pulling back on the delivery tube  4222 , which is connected to the proximal end of the catheter. After the anchor is deployed as described in conjunction with  FIGS. 31 and 32 , the catheter system  4250  is withdrawn from the patient. The catheter  4302  has no edges that could catch on the sleeve  202  as it is pulled back through the stomach  102  and the esophagus because the ball is left behind. This zero profile catheter design is important since it is typically very difficult to withdraw devices from the gastro-intestinal tract while leaving catheters or other devices behind. 
     A method for accessing the small bowel by passing a catheter through the mouth has been described in conjunction with  FIGS. 43-45 . The low profile catheter can also be used for accessing the small bowel through an incision in the stomach. Instead of delivering the catheter through the top of the stomach as shown in  FIG. 43 , the catheter is delivered through the stomach, for example, through an incision at position  4304  in  FIG. 43 . The bowel is filled with a fluid, preferably water, and then the thin, flexible catheter with a large, atraumatic ball tip through the bowel is passed through the bowel as described in conjunction with  FIG. 43-45 . 
       FIGS. 46-48  illustrate embodiments for attaching a releasable spherical shaped element to the distal end of the catheter.  FIG. 46  is a plan view of the distal end of the catheter system illustrating a releasable ball tip mechanism. As discussed in conjunction with the catheter system shown in  FIG. 42 , a sleeve retention wire  4208  travels through second lumen  4204  in the catheter shaft  4200  exits the second lumen  4204  through proximal skive hole  4214  and re-enters the second lumen through distal skive hole  4216 . 
     The ends of wire  4600  are attached to the ball  4218  and the wire  4600  is looped through sleeve retention wire  4208  to hold the ball  4218  at the distal end of the inner shaft  4200  of the catheter. The ball  4218  is released by pulling back on sleeve retention wire  4208  with fitting  4220  ( FIG. 42A ) until wire  4600  is no longer held by sleeve retention wire  4208 . The ball  4218  then falls off the distal end of the inner shaft of the catheter  4200  and exits the body through normal peristalsis through the intestines. 
       FIG. 47  is a plan view of the distal end of the catheter illustrating an alternative embodiment of a releasable ball tip mechanism. The inner shaft  4200  fits in recess  4706  in the ball  4218 . The sleeve retention wire  4208  exits the inner shaft  4200  through proximal skive hole  4214 , pierces the sleeve  202  and re-enters the inner shaft  4200  through distal proximal skive hole  4216 . The distal end of the sleeve retention wire  4208  is formed into a coil shape  4700  and sits in a pocket  4702  in the ball  4218 . The pocket  4702  is connected to the recess  4702  through hole  4704 , which is of a smaller diameter than the recess  4702  and the pocket  4700 . The distal end of the sleeve retention wire  4208  is annealed so that the sleeve retention wire  4208  can be pulled back in a proximal direction and will straighten out to allow the wire to pass through hole  4704 . 
       FIG. 48  is yet another embodiment of a releasable ball tip mechanism. The inner shaft  4200  fits in recess  4706  in the ball  4218 . The sleeve retention wire  4208  exits the inner shaft  4200  through proximal skive hole  4214 , pierces the sleeve  202  and re-enters the inner shaft  4200  through distal proximal skive hole  4216 . 
     The ball  4218  includes two holes  4800 ,  4802  extending from the recess  4706  to the exterior surface of the ball  4218 . The distal end of the sleeve retention wire  4208  passes through hole  166  and is looped back into hole  167 . As the sleeve retention wire  4208  is pulled proximally, the wire  4218  is pulled back through hole  4802  and then through hold  4800  and the ball  4218  is released from the distal end of the catheter. 
       FIG. 49  is a cross sectional view of an alternative embodiment of a solid spherical shaped element. A ball  4900  is fabricated in two halves,  4902  and  4904 . The sleeve retention wire  4006  fits into an S shaped track  4908 . The S shape of the track  4908  creates sufficient friction to hold the ball on the end of the catheter during delivery of the gastrointestinal implant device. The sleeve retention wire  4600  fits snugly in the channel  4908  but can be pulled proximally to release the sleeve retention wire  4600  from the ball  4900 . The catheter shaft fits in the recess  4906 . 
     A low profile balloon can be used instead of the ball  4218  at the distal end of the catheter.  FIGS. 50A-50B  is a plan view of the distal end of the catheter shown in  FIG. 44  with a low profile balloon. In the embodiment shown, a low profile balloon replaces the ball at the distal end of the catheter shown in  FIG. 44 .  FIG. 50A  is a plan view of the distal end of the catheter with an inflatable spherical shaped element.  FIG. 50B  is a plan view of the distal end of the catheter after the inflatable spherical shaped element has been inflated; 
     Referring to  FIG. 50A , a silicone or latex sleeve  202  is attached to the distal end of the catheter shaft  4302 . Filling holes  5010  connect with the inner lumen of the catheter to provide a passage for inflation of an inflatable spherical shaped element (balloon)  5008 . The balloon  5008  is attached to the shaft  4302  with a metal band  5000  that has a tapered proximal transition  5002  to minimize edges that could catch on the sleeve  202  after delivery of the sleeve  202 . The metal band  5000  is about 0.003-0.005″ (0.076-0.127 mm) thick. The balloon  5008  can be thin wall molded, tubular polyurethane or silicone. The balloon is stored along the distal catheter shaft  4302  with the distal end pushed into the lumen of the catheter shaft and attached to the catheter shaft  4302  with a plug  5006  to keep the balloon from expanding beyond the tip of the catheter. 
       FIG. 50B  illustrates the distal end of the catheter  4302  after the balloon  5002  has been expanded into a spherical shape. The balloon is expanded by fluid, which flows through the catheter shaft and enters the balloon  5008  through the fluid passage holes from the catheter shaft. The plug  5006  at the end of the catheter shaft ensures that the balloon acts like the ball shown in the embodiment in  FIG. 50  by limiting expansion of the balloon beyond the tip of the catheter and the plug also provides some lateral strength to the balloon. By replacing the ball with a balloon at the distal end of the catheter, the distal tip is more stable for axial compression. Also, the catheter will not deflect with side loading. 
     The further one tries to pass a device into the intestine, the more difficult it is since friction and tortuosity increase.  FIG. 51  is a plan view of an alternative delivery system for delivering a gastrointestinal implant device. The delivery system enables delivery of a long sleeve into the intestine and includes a distal pill with folded sleeve material inside. Peristalsis carries the pill distal in the intestine, causing the sleeve material to unfurl. 
     The delivery system is described for delivering the embodiment of the gastrointestinal device described in conjunction with  FIG. 28 . However, the delivery system is not limited to the delivery of a distal section of the sleeve for this embodiment of the gastrointestinal implant device. As described in conjunction with  FIG. 28 , the gastrointestinal device includes a proximal ring  2802 , a distal ring  2803  and a sleeve  202 . The proximal section of the sleeve is fully deployed and some amount of the distal section of sleeve  202  is packed into a pill  5100 . 
     The gastrointestinal implant device is delivered as previously described into the proximal intestines. Once deployed in the intestines, peristalsis from the natural activity of the intestine pulls the pill  5100  distally through the intestine. As the pill is pulled distally, the distal section of the sleeve  202  pulls out of the pill and deploys straight in the intestine. Peristalsis pulls the pill through the remainder of the intestines and the pill finally exits the body. 
     A one-foot length of sleeve material can be packed into a pill with length of 1″ (25.4 mm) and diameter of 0.47″ (12 mm). Therefore, if one only wishes to pass the catheter 2 feet into the intestine for delivery of the gastrointestinal device, the pill  5100  enables a 3 foot sleeve to be delivered with the additional 1′ distal section of the 3-foot sleeve delivered in the pill  5100 . 
       FIG. 52  is a plan view of another embodiment of the delivery mechanism shown in  FIG. 51 . The delivery mechanism enables delivery of a long sleeve into the intestine and includes encapsulated sleeve materials formed into pill shapes. Each pill dissolves in the body at different rates enabling the sleeve to be pulled distally by peristalsis as it unfolds once the pill covering dissolves. 
     The delivery mechanism is shown for delivery of the gastrointestinal implant device described in conjunction with  FIG. 28 . The first section of the sleeve  202  is fully deployed after the gastrointestinal implant device has been delivered into the proximal intestine as previously described. A plurality of distal sections of the sleeve  202  are coated to form a plurality of dissolvable pills  5200 ,  5202 ,  5204 . The coatings applied to form each respective pill  5200 ,  5202 ,  5204  are made of a dissolvable material, with each coating tailored to dissolve at different times depending on the polymer make up and the environment. Each pill  5200 ,  5202 ,  5204  is carried distally by peristalsis. The coating on the first pill  5200  is selected to dissolve first. After the coating on the first pill  5200  has dissolved, the second and third pills  5202  and  5204  pull the compacted sleeve  202  distally. The coating on the second pill  5202  dissolves next, as the third pill  5204  pulls the sleeve more distally. Finally, the coating on the third pill  5204  dissolves and the sleeve  202  is fully deployed. The plurality of dissolvable pills enables the ultimate delivery of many feet of sleeve material with the simpler delivery of only an initial 1-2 foot section of the sleeve into the proximal intestine. As described in conjunction with the embodiment shown in  FIG. 51 , a one-foot length of sleeve material can be packed into a pill with length of 1″ (25.4 mm) and diameter of 0.47″ (12 mm). 
     A number of biodegradable materials may be used for the coatings on the pills including polyethylene glycols (PEG), polylactic acids (PLA) and polycaprolactones (PCL). These materials are made in formable resins or in liquids that can be converted to solids through various types of chemical and photochemical reactions. These materials break down into chemicals that are safe to internal tissues. These resins are made biodegradable by formulating a base molecule with a hydrolytically unstable link within the base chain. 
     For example, PEG is made biodegradable by incorporating lactic acid into the base chain. One end of the lactide molecule forms a link that will break down rapidly in the presence of water. One means of controlling the rate of degradation is by varying the number of lactide elements within the base chain. The greater the number, the faster the chain will break down. Additionally, the percent solids or density of the resulting solid is varied to alter degradation rates. Denser materials take longer to break down. Also, hydrolytically unstable bonds break down faster in elevated pH environments. Such an environment occurs naturally within the small intestines, on the outside of the sleeve where bile and bicarbonates are deposited. 
       FIGS. 53A-53C  illustrate a method for delivering an alternate embodiment of the catheter system  4250  having a central lumen for placement over a guide wire.  FIG. 53A  is a sectional view of a portion of the digestive tract in a body illustrating an enteroscope  5300  extending through the stomach, through the pylorus  104  to the duodenum  104 . A guide wire  5302  is then passed through the enteroscope  5300 . After the guide wire has been passed through the enteroscope  5300  is removed.  FIG. 53B  is a sectional view of a portion of the digestive tract in a body illustrating the guide wire  5302  extending through the stomach  104  and the duodenum  104  after the enteroscope  5300  has been removed. The catheter system follows a guide wire  5302  through the esophagus and the stomach to the pylorus portion  108  of the stomach  102 .  FIG. 53C  is a sectional view of a portion of the digestive tract in a body illustrating the catheter extending through the stomach  102  and duodenum  104  over the guide wire  5300 . After the gastrointestinal implant device has been delivered, the catheter  4200  is pulled back through the stomach. After the catheter has been removed, the guide wire  5302  is pulled back through the intestines and the stomach  102 . 
     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.