Satiation devices and methods

ES 2 575 354 T3

DESCRIPTION

Satiety Devices and Procedures

Field of the invention

The present invention relates, in general, to the field of devices and methods to achieve weight loss in humans and, specifically, to the use of implantable devices within the human stomach to control feelings of hunger and / or limit intake. food.

Background of the invention

Various medical approaches are used to control obesity. These approaches include diet, medications, and surgical procedures. One of the most successful surgical procedures is the vertical gastropexy or proximal gastric pouch procedure in which a portion of the proximal stomach is formed into a small pouch with a small opening in the rest of the stomach. This proximal gastric pouch may include a Roux-Y anastomosis in which a portion of the jejunum is connected to the pouch in order to divert food from the proximal region of the stomach into the intestine, thus minimizing the absorption of food into the torrent. blood. However, known complications are present with each of these procedures and more options for success are desired.

Berry (US Patent 5,306,300) describes a tubular digestive screen that is placed in the lower part of the stomach and threads through the pylorus, duodenum, jejunum, and possibly the ileum. The screen is intended to interfere with digestion, particularly of lipids.

Other alternatives include the implantation of gastric balloons that prevent overeating by occupying volume within the stomach. Unfortunately, gastric balloons can migrate down the GI tract, causing obstruction, requiring removal.

Therefore, it is desirable to provide a successful and minimally invasive alternative to existing approaches to obesity control.

Summary of the invention

A satiety device utilizing principles of the present invention includes a sleeve or liner positioned within the stomach. The food ingested by the patient passes through the sleeve or liner, thus minimizing contact between the ingested food and the stomach. It is believed that over time, reduced contact between food and the stomach will result in less ghrelin production by the patient and a consequent decrease in appetite. In some embodiments, the satiety device may also include a proximal bag and / or a distal bypass tube.

Brief description of the drawings

Figure 1 is a schematic illustration of a human stomach and a portion of the small intestine.

Figure 2A is a side elevation view of a first embodiment of a satiety device.

Figure 2B is a side elevational view of the bag and channel of the embodiment of Figure 2A.

Figure 3 is a schematic illustration of a human stomach illustrating in vivo positioning of the embodiment of Figure 2A.

Figure 4 is a schematic illustration of a human stomach illustrating in vivo positioning of a second embodiment of a satiety device.

Figure 5 is a schematic illustration of a human stomach showing in vivo positioning of an exclusion liner

Figure 6 is a schematic illustration similar to Figure 5 showing an exclusion liner having a distal tube.

Figure 7 is a schematic illustration similar to Figure 5 showing an exclusion liner having a proximal pocket.

Figure 8 is a schematic illustration similar to Figure 5 showing an exclusion liner having a proximal end in the proximal midstomach / antrum.

Figure 9 is a schematic illustration of a human stomach and proximal small intestine showing the placement of a bypass tube extending from the proximal stomach into the intestine.

ES 2 575 354 T3 slim.

Figure 10A is a cross-sectional side elevation view showing an example of a mechanism for securing the bag and tube of Figure 9.

Figure 10B is a cross-sectional side elevation view showing a second example of a mechanism for attaching the bag and tube of Figure 9.

Figure 11 is a schematic illustration of a pylorus showing a tether connecting the proximal and distal portions of the tube of Figure 9 and extending beyond Vader's ampulla.

Detailed description

An anatomical view of a human stomach S and associated features are shown in Figure 1. The esophagus E supplies food from the mouth to the stomach S. The line z or gastroesophageal junction Z is the irregularly shaped border between the thin tissue of the esophagus and the thickest tissue of the stomach wall. The gastroesophageal junction region G is the region encompassing the distal portion of the esophagus E, the line z, and the proximal portion of the stomach S.

The stomach S includes a fundus F at its proximal end and an antrum A at its distal end. Antrum A feeds into the P pylorus which joins duodenum D, the proximal region of the small intestine. Inside the P pylorus there is a sphincter that prevents the reflux of food from the D duodenum into the stomach. The middle region of the small intestine, positioned distally from the D duodenum, is the jejunum J.

Ghrelin is a satiety hormone secreted by cells in the stomach and small intestine. Increased ghrelin production, for example, before a meal, causes a person to experience hunger. After the person has eaten, the production of ghrelin decreases. It is currently believed that 85% of ghrelin-secreting cells are found in the stomach, with the remaining 15% in the antrum and small intestine. Obese patients have been found to possess significantly higher levels of ghrelin than non-obese patients. Furthermore, recent studies have found that a patient's ghrelin production decreases significantly after gastric bypass procedures, such as the Roux-Y procedure described above. Various versions of the embodiments described herein provide an exclusion sleeve or liner located within the stomach and extending from the proximal end or the midstomach to the distal stomach or the small intestine. Over time, the presence of the exclusion cuff will cause the ghrelin-secreting cells to decrease ghrelin production, causing the level of hunger experienced by a patient to decrease and resulting in weight loss by the patient.

Some of the exclusion sleeve embodiments also include a pouch or funnel placed in the gastroesophageal junction region to form a small reservoir that collects chewed food from the esophagus. The bag can limit the amount of food that can be consumed at one time. Additionally or alternatively, when the bag is filled with food, it can distend, exert pressure against the upper stomach and lower esophageal sphincter causing the patient to experience feelings of satiety. Over time the food within this reservoir descends into the exclusion sleeve through a distal opening in the bag. The bag may optionally include a proximal tubular extension positionable within the esophagus to facilitate the flow of food from the esophagus into the bag. Various bags of a type suitable for use with the exclusion sleeve are described in US application 10 / 118,289, filed April 8, 2002.

The devices can be modulated in that multiple components, (eg, a cuff and bag), when they are to be implanted, the various components can be provided separately from one another. In such a modular system, the separately implanted components may be attached to each other within the body during implantation, or certain of them may remain unattached to each other, even after implantation. Alternatively, the physician can assemble the components together immediately prior to implantation. Modular components are desirable in that they allow the physician to select sizes for each component that are appropriate for the patient.

The implantation of the described devices is preferably carried out endoscopically, passing the devices through the esophagus, preferably under endoscopic visualization. Alternatively, the devices can be implanted using surgical or laparoscopic procedures.

One embodiment of a satiety device is illustrated in Figure 2A and includes a bag 12 positioned within an elongated exclusion sleeve 14. For the purposes of this application, the term "satiety devices" will be used to mean devices intended to induce weight loss in one or more of a variety of ways. These include, but are not limited to, physically restricting the amount of food that can be consumed, and / or imparting pressure against portions of the body (e.g., stomach, esophagus, esophageal sphincter, etc.) causing the patient to experience sensations of satiety, and / or that affect the levels of hormones or other substances in the body that control or affect the feeling of hunger, and / or that affect the amount of ingested food absorbed by the body.

ES 2 575 354 T3

Bag 12, shown without the cuff in Figure 2B, includes a funnel-shaped proximal portion 16 with an opening 18 that can be positioned in the region of the gastroesophageal junction (and preferably below the Z line) as shown in Figure 3. Although a funnel shape is preferred here, a variety of alternative shapes can be used for the proximal portion of the bag. For example, the bag may have a much shorter proximal to distal dimension and therefore take the shape of a shallow saucer with a small hole in its lower surface. Other examples include, but are not limited to, egg shapes, other conical shapes, such as a "top" shape, cylindrical shapes, and other symmetrical or asymmetrical shapes.

Due to its small volume (which can be on the order of about 2 cc to 300 cc in volume, but is preferably in the range of 10 to 30 cc), the bag functions to limit the amount of food that can be consumed at one time. time. Over time the food within this reservoir descends into the exclusion sleeve 14 through a distal opening in the bag.

A distal channel 20 extends from proximal funnel-shaped portion 16 and includes a distal opening 22. In this embodiment, channel 20 tapers outward from funnel 16 to form a valve 24 between the funnel and channel. Valve 24 may be formed of a resilient material that allows the valve to be opened to increase in size to allow large pieces of food to pass through. If desired, the diameter of valve 24 can be adjustable by endoscopic means, such as by tightening a ligature around the valve, inflating an inflatable cuff positioned around the valve, or using various other means. This increases the effectiveness of the bag by decreasing the outlet diameter - thereby causing the food to exit the bag more slowly and prolonging the feeling of fullness experienced by the patient. Similarly, the diameter of valve 24 can be endoscopically increased by deflating a fluid-filled restrictive cuff, using a tool to cut or narrow the valve, or the use of various other means, to increase the patient's ability to tolerate the bag. allowing a faster emptying of the bag.

The bag 12 may be formed of a flexible material that will prevent the passage of food through the sides of the bag. Examples of such materials include, but are not limited to, polyesters (eg Dacron® polyester), ePTFE fabric (eg GoreTex® fabric or others), a polyurethane such as ChronoFlex® polyurethane, nylon fabrics, silicone, other materials. polymeric, and bioabsorbable materials (eg, PLLA, PGA, PCL, polyamhydride, etc.). The bag may be formed from a composite of compatible, semi-compatible and / or non-conforming materials that give different regions of the bag different degrees of elasticity in order to allow expansion / boundary of the bag at various locations. For example, it may be desirable to provide the bag with a sufficiently elastic outlet opening to prevent occlusion in the event that a large chunk of food is swallowed and / or to control the outlet pressure of the food from the bag, while that the proximal end of the bag can be stiffer to avoid bulging. Various degrees of compliance can also be built into the bag by varying the thickness of the cross section in different regions of the bag. The material may be coated with a chemically inert, biocompatible lubricating material, such as paraleyne, to reduce friction on the surface of the base material that will help prevent food from sticking to and accumulating on the device.

Sleeve 14 is a flexible tube having a proximal opening 23 and a distal opening 26. The material of the sleeve may be similar to the material described with respect to bag 12, but must be flexible enough to allow peristalsis. The exterior of the sleeve material can be impregnated with substances known to inhibit the release of ghrelin or other hormones associated with the feeling of fullness. Such substances can be chemical or pharmaceutical substances, therapeutic molecules or cells, or genetic material. The sleeve can also be impregnated with an acid to inhibit gastrin production, or its exterior can be impregnated with an antigastrin antibody.

Cuff 14 and bag 12 are preferably attached to each other at their respective proximal openings 18, 23 using sutures, clips, adhesives, or other suitable means. These components can be attached to one another during fabrication or just prior to implantation, or they can be implanted separately.

The proximal portion of sheath 14 contains a plurality of openings 28 sized to allow gastric secretions to enter cuff 14 to aid in the digestion of food that has passed from bag 12 to cuff 14 and to allow drainage of the cuff 14. stomach secretions. Stomach secretions exit the stomach through the sheath and drain into the pylorus. The openings 28 may take the form of perforations or slots in the wall of the sleeve. Alternatively, the openings may be in the form of openings in the mesh or porous regions in a portion of the sleeve. For example, ePTFE with an open cell structure is a material that can be constructed to allow gastric secretions to enter without allowing food to escape.

In the embodiment shown in Figure 3, the openings are positioned such that when the bag 12 is placed within the sleeve 14 for use, the distal opening 22 of the channel 20 is preferably distal to the openings 28 in order to prevent it from food comes out of the sleeve through the openings 28. The openings 28 can be located anywhere else as well, in particular, if the openings are small enough to prevent food from passing through. Examples of alternative locations for the openings include locations near the distal end of the sleeve (see Figure 4), or locations substantially along the entire length of the sleeve.

ES 2 575 354 T3 sleeve length.

The diameter of the sleeve 14 is large enough to allow the bag to be enclosed within the sleeve 14, but is preferably narrow enough to allow the acids produced within the stomach to flow into contact with the walls of the antrum. Such contact is believed to be necessary for normal regulation of the hormone gastrin. Gastrin is a physiological regulator of gastric acid secretion in the stomach. Increased gastrin levels result in increased gastric acid secretion. Acid levels that are too high can cause ulcers.

Gastrin secretion (and therefore the resulting gastric acid secretion) is inhibited when cells in the antrum detect a low pH. Therefore, it is important that acids in the stomach contact the antrum to ensure normal regulation of gastrin. If acids are not allowed to contact the antrum, gastrin production would increase, and therefore could cause increased gastric acid production that could lead to stomach ulcers.

Procedures for implantation of saturation devices such as bag 12 are shown and described in US application 10 / 118,289 filed April 8, 2002. For example, some of the described procedures involve packaging the satiety device within a deployment tube, inserting the distal end of the tube into the stomach (preferably from the esophagus), ejecting the satiety device from the tube using a rod. of thrust passed through the tube, and then securing the satiety device by means of sutures, clips, adhesives, radial forces, stents or stent-like structures, etc. Such procedures can be used to implement the saturation devices described herein, including bag 12 and cuff 14.

During implantation bag 12 is secured in the gastroesophageal junction region G using sutures, clips, adhesives, stents or stent-like structures, or other suitable means. One suture attachment device that was found useful for applying sutures between the bag and tissue is the "SewRight" suture device available from LSI Solutions of Victor, New York.

Although the bag can be attached to esophageal tissue, it is more preferable to apply sutures / clips below the Z line to allow attachment to the thicker tissue of the stomach wall. Suture anchor points, which may take the form of holes, anchor loops, grommets, windows or washers 30 in the bag can be used to provide regions (which may be reinforced) for anchoring the sutures. Although few or many such attachment stitches / clips may be used as needed, at least four of these stitches are desirable, such as at 90 ° intervals around the bag, in order for the bag to be attached around the bag. of the entire circumference of the tissue. Suture attachment points can be made of a suitably dense radiopaque material, such as titanium or gold, to add to the visualization of the device during or after the procedure. Each suture attachment point can also be marked with a different color to facilitate identification and orientation of the sutures. If the bag is formed of a less resistant material, the proximal portion of the bag (where the eyelets 30 are located) may be formed of a more durable material, such as a woven material, Dacron® polyester or ePTFE fabric in order to provide a more secure sewing region. Although loops, grommets, washers or reinforced regions may be advantageous, the bag can alternatively be provided without suture anchor points formed of special materials (with or without identification markings) - in which case the sutures are passed directly through the bag material.

The material of the bag and / or the flexible sleeve can be reinforced with, constructed of, or supported by support elements, such as a soft mesh, a cage structure, ribs, rings, etc. The support members can be formed of stainless steel, polymer, shape memory materials such as nitinol, memory alloys, or shape memory polymers, or thickened areas of material. The bag and / or the cuff may be constructed to be self-expanding, such that the springs of the bag and / or the cuff open radially in an expanded state after ejection of a deployment device or catheter as described above. .

The proximal end of sleeve 14, near proximal opening 23, may be attached to bag 12 on its own, or it may be attached to bag 12 and surrounding tissue. The sleeve 14 is attached at its distal opening to the distal stomach (eg, at the antrum) near the pylorus, in order to allow food exiting the sleeve 14 to flow out of the stomach into the small intestine. Attachment is accomplished using sutures, clips, adhesives, stents or stent-like structures or other suitable means.

Figure 4 shows an alternative embodiment of a satiety device 10a using a bag 12a and a sleeve 14a. The satiety device 10a differs from that of Figure 3 primarily in that the bag 12a is provided without a distal channel (see channel 20 in Figure 3), and in that the openings 28a in the cuff are located at the distal end of the cuff in order to allow drainage of gastric secretions in the cuff 28a and from the cuff to the pylorus. Drainage of gastric secretions is desirable to avoid accumulation of such secretions in the stomach.

The sleeve 14a (and also the sleeve 14 of Figure 3) can be semi-permeable, allowing the

ES 2 575 354 T3 gastric secretions enter without allowing food to escape. Materials such as ePTFE with an open cell structure (eg, node to fibril lengths of 20-100 microns) are suitable for this purpose.

The embodiments of Figures 3 and 4 are believed to cause weight loss in a number of ways. First, when the pouch is filled with food it can dilate, imparting pressure against the upper stomach and lower esophageal sphincter causing the patient to experience feelings of fullness after consuming small amounts of food. Second, it is believed that the isolation of consumed food from the stomach walls using the exclusion sleeve 14, 14a will lead to a temporary increase in the patient's ghrelin production followed by a "burn-out" phenomenon over time. in which ghrelin is reduced, in turn, leading to a decrease in feelings of hunger. Third, digestion is delayed and absorption of food is minimized.

Figures 5 to 8 show additional embodiments that also control satiety by isolating consumed food from the stomach walls in order to decrease the time of day-to-day production of ghrelin by the patient due to the phenomenon of "burning" previously described. Each of these embodiments includes an exclusion liner that is positioned within the stomach such that consumed food passes through the lining and then exits the liner to flow into the small intestine through the pylorus.

Referring to Figure 5, a first exclusion liner 32 includes a proximal opening 34 positioned in the proximal stomach, such as in the gastroesophageal junction region G, and a distal opening 36 positioned in the antrum A, preferably adjacent to the pylorus P . Liner 32 can be provided to substantially line the stomach while still allowing space for gastric acids (marked H + in Figure 5) to contact the walls of the antrum surrounding the liner - to avoid overproduction of gastrin as described above. Alternatively, the liner can have a significantly narrower diameter if desired. As shown in Figure 5, the liner 32 reduces contact between the ingested food and the stomach, including the bottom and the antrum.

The proximal region adjacent to proximal opening 34 is preferably attached to tissue in the region of the gastroesophageal junction below the Z line using sutures, clips, adhesives, stents or stent-like structures or other suitable means. The distal region adjacent to the distal opening may be secured in a leak-proof manner to the distal antrum, or it may be secured more flexibly to allow gastric secretions to flow out of the stomach into the pylorus (see arrows in Figure 5 ). For example, clips or sutures, etc., can be applied in a way that leaves a space between the distal opening 36 and the pylorus to allow drainage of gastric secretions. Alternatively, if such drainage is desired, liner 32 may be provided with a plurality of openings (see, for example, openings 28a in Figure 4) that allow gastric secretions to flow into the lining and then into the pylorus. As another alternative, the liner may be supported by a cage structure that has elastic cage elements that make contact with the stomach walls to prevent migration of the liner into the stomach, but which leaves a clearance between the stomach walls and the exterior of the cladding. Cage structures of a type that can be adapted for this purpose are shown and described in US application 09 / 940,110, filed August 27, 2001.

Figure 6 shows an exclusion liner 32a that is similar to the sleeve 32 of Figure 5, but further includes a distal tube 38 that is secured to the pylorus or duodenum by sutures, anchors, clips, stents, or structures like stents, adhesives, etc. Again, this distal connection can be leak-proof to prevent drainage of secretions, or it can be configured to allow such drainage.

Figure 7 shows an exclusion liner 32b that is similar to the liner of Figure 5, except that it includes a proximal pocket 40 attachable to the gastroesophageal junction region. As with the embodiment of Figures 3 and 4, the bag 40 is filled with food as the patient eats, causing the patient to experience feelings of fullness after consuming small amounts of food. Bag 40 may be integral with liner 32b, or it may be removably attached prior to or during implantation. As with the embodiments of Figures 5 and Figure 6, the distal end of liner 32b may be attached to the distal antrum in a manner that allows drainage of secretions present outside of the liner, or in a manner that occludes such drainage. . The embodiment of Figure 7 may also be provided with a distal tube similar to the distal tube 38 of the embodiment of Figure 6.

Figure 8 shows an antral exclusion liner 32c provided to extend from the mid stomach or proximal antrum to the distal antrum. The liner 32c includes a large proximal opening 42 and a smaller distal opening 44, as shown. The proximal region of liner 32c is attached to the surrounding walls of the stomach, and the distal region is attached to the distal antrum. Liner 32c may be secured in a manner that allows some food and stomach secretions to flow around liner 32c as indicated by arrows in Figure 8, or it may be securely secured against stomach walls such that all food and stomach secretions are directed through lining 32c. The embodiment of Figure 8 may be provided with a distal tube similar to tube 38 of Figure 6.

ES 2 575 354 T3

Materials that can be used for the liners of Figures 5-8 include flexible materials that prevent passage of food through the sides of the bag. The materials can be impermeable or slightly permeable to fluids. Poorly permeable materials (eg ePTFE with open cell structure on the order of node 20-100 microns to fibril length) may be desirable in that they allow gastric secretions to pass into the lining without allowing food to escape.

Examples of useful liner materials include, but are not limited to, polyesters (eg Dacron® polyester), ePTFE fabric (eg GoreTex® fabric or others), a polyurethane such as ChronoFlex® polyurethane, nylon fabrics, silicone, other polymeric materials, and bioabsorbable materials (eg, PLLA, PGA, PCL, polyamhydride, etc). The liners can be formed from a composite of elastic, semi-elastic and / or non-elastic materials that give different regions of the sleeve / bag different degrees of elasticity in order to allow / limit expansion of the sleeve / bag at various locations. For example, it may be desirable to provide the liner with an exit port elastic enough to prevent occlusion in the event that a large chunk of food is ingested. The material may be coated with a chemically inert, biocompatible lubricating material, such as paraleyne, to reduce friction at the base.

The exterior of the coating material can be impregnated with substances known to inhibit the release of ghrelin or other hormones associated with the feeling of fullness. Such substances can be chemical or pharmaceutical substances, therapeutic molecules or cells, or genetic material. The coating can also be impregnated with an acid to inhibit gastrin production, or its exterior can be impregnated with an antigastrin antibody, or any of a variety of drugs or therapeutic molecules.

The liner can be reinforced with, constructed of, or supported by a supporting structure, such as a soft mesh, coil, cage structure, ribs, rings, etc. The support structure can be formed of stainless steel, polymer, shape memory materials (for example, nitinol, shape memory alloys, or shape memory polymers), bioabsorbable materials or, in the case of a silicone coating. , thickened regions of silicone. The support structure can be located on the inside or outside of the cladding material. It can be molded into or sewn into the facing material, or it can be attached by a suitable adhesive. If a tight woven mesh or tightly wound coil is provided, the flexible material can be eliminated. Alternatively, a mesh can be provided with a polymeric material embedded in the interstices of the mesh, in which case a separate inner or outer covering of lining material can be removed. The polymer can be impregnated with an agent that will decrease ghrelin secretion or neutralize stomach acidity.

The inside diameter of the liner (and / or the support structure) may be coated with a lubricating material such as Teflon or parylene to facilitate the passage of food through the liner.

The liner is preferably constructed to be self-expanding, such that the bag is radially released in an expanded state after ejection from a delivery device or catheter. In an example of a liner implementation method such as the liners of Figures 5-8, the liner can be compressed and inserted into a deployment tube. In this example, the distal end of the deployment tube is inserted (preferably through the esophagus) into the stomach and the liner is expelled from the tube using a push rod passed through the tube. The lining expands within the stomach, and the physician attaches the lining to the stomach using sutures, clips, adhesives, stents or stent-like structures, radial forces, etc.

Figure 9 illustrates an alternative satiety device that includes an elongated bypass tube 46 that is implanted to extend from the proximal stomach, through the pylorus, and into the small intestine (e.g., through the first 24 inches (60, 96 cm) of the small intestine). As with the previous embodiment, tube 46 reduces the amount of contact between the ingested food and the stomach and therefore may over time result in less ghrelin production. It also works similar to a Y en Roux shunt in that it reduces the amount of surface area of ​​the small intestine that is available for absorption of food. The tube is preferably made of a thin-walled polymer that is flexible enough to allow peristalsis in the small intestine. It also bypasses the bile and pancreatic ducts, which insert digestive enzymes into the small intestine.

It may be desirable to position the tube so that it does not make contact with Vader's ampulla (an opening in the duodenum through which bile passes into the duodenum) to minimize the possibility of irritation and cholecystitis. For example, a narrow strap 50 (FIG. 11) can connect the proximal portion 52a of the tube (which is disposed proximal of the Vader ampoule) to the distal portion 52b of the tube in order to avoid obstruction of the ampoule. Distal portion 52b may include a funnel-shaped proximal end to facilitate re-entry of food into tube 46 after food has passed the Vader ampoule.

Finally, referring back to Figure 9, tube 46 may be provided with a proximal bag 48, similar to the bag of Figure 3, which can distend when filled with ingested food, impart pressure against the upper stomach, and the lower esophageal sphincter causing the patient to experience feelings of satiety. Bag 48 and tube 46 can be implantable separately and then attached to each other in situ.

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Figures 10A and 10B show two examples of configurations for attachment of bag 48 and tube 46. In one configuration, the proximal end of tube 48 can be inserted into the distal opening of bag 46 as shown in Figure 10A. . In another, the distal end of bag 46 may be inserted into the proximal end of tube 48 as shown in FIG. 10B. Of course, other means of attachment may be used, including sutures, hooks, stents, or stent-like structures and / or adhesives.

Various embodiments of saturation devices have been described herein. These embodiments are given by way of example and are not intended to limit the scope of the present invention. It should be appreciated, on the other hand, that the various features of the described embodiments can be combined in various ways to produce numerous additional embodiments. Furthermore, although various materials, dimensions, shapes, implantation sites, etc., have been described for use with described embodiments, other than those described may be used without exceeding the scope of the invention.

The procedure is not part of the invention defined by the following numbered paragraphs also described above.

1. A procedure for inducing weight loss in a patient having a stomach, antrum, and a pylorus, the procedure comprising the steps of:

placing a prosthesis within the stomach of a patient, the prosthesis having a proximal opening and a distal opening and a passageway extending between the proximal and distal openings;

causing the patient to ingest food material, passing at least a portion of the food material through the proximal opening in the prosthesis;

allow food material to exit the prosthesis and flow into the pylorus; and allowing gastric secretions from the stomach to flow around at least a portion of the prosthesis and into the pylorus.

two. The procedure of paragraph 1, in which the cause and allow steps reduce the amount of food material absorbed by an interior surface of the stomach.

3. The procedure of paragraph 1, further including the steps of repeating the steps of causing and allowing several times, resulting in a decrease in ghrelin secretion by the stomach and therefore a reduction in the sensation of hunger in the patient.

Four. The procedure in paragraph 1, in which the cause step reduces contact between the ingested food material and an interior surface of the antrum.

5. The method of paragraph 1, wherein the stomach includes a bottom and wherein the step of causing reduces contact between the ingested food material and an interior surface of the bottom.

6. The procedure in paragraph 1, in which the step of allowing gastric secretions to flow into the pylorus includes allowing gastric secretions to flow from the stomach into the prosthesis.

7. The procedure in paragraph 6, in which gastric secretions flow into the prosthesis through an opening in the proximal part of the prosthesis.

8. The procedure of paragraph 6, in which gastric secretions flow into the prosthesis through one or more openings in a wall of the prosthesis.

9. The procedure of paragraph 8, wherein one or more apertures are provided to allow gastric secretions to flow into the prosthesis while substantially preventing ingested food material from passing through the one or more apertures.

10. The procedure of paragraph 1, in which at least a part of the gastric secretions flows into the pylorus without passing through the prosthesis.

eleven. The procedure of paragraph 1, wherein the positioning step includes obtaining a proximal portion of the prosthesis within the gastroesophageal junction region such that the proximal opening receives food directly from the esophagus.

12. The procedure of paragraph 11, wherein the step of fixation includes fixation of the proximal part to the tissue below the Z line of the gastroesophageal junction region.

13. The procedure of item 1, wherein the positioning step includes obtaining the distal portion of the prosthesis within the distal portion of the stomach.

14. The procedure of section 1, where the prosthesis is expandable from a folded position in which the

ES 2 575 354 T3 prosthesis has a first diameter to an expanded position in which the prosthesis has a second, larger diameter, and in which the placement step includes the steps of:

With the prosthesis in the folded position, insert the prosthesis into the stomach; and expanding the prosthesis from the collapsed to the expanded position.

fifteen. The procedure in paragraph 14, where the prosthesis self-expands to the expanded position.

16. The procedure of paragraph 1, in which the proximal opening of the prosthesis is smaller than the distal opening.

17. The procedure in paragraph 1, which also includes the steps of:

placing a tubular bag in the gastroesophageal junction region of the stomach, the bag including a proximal opening and a distal opening;

cause food ingested by the patient to pass from the esophagus into the proximal opening of the pouch, and from the pouch through the distal opening and into the tubular prosthesis.

18. The procedure in paragraph 17, wherein the proximal opening of the bag is smaller than the distal opening.

19. The procedure of paragraph 17, wherein the bag is tapered from a proximal portion of the bag to a more distal portion of the bag.

twenty. The method of paragraph 18, wherein a distal portion of the bag includes an elongated channel, and wherein the distal opening is in the channel.

twenty-one. The procedure of paragraph 20, wherein a one-way valve is provided between the channel and the bag, and wherein the method includes preventing flow of food material from the channel into the bag.

22. The procedure of paragraph 17, in which food material passed into the bag causes the bag to distend and exert pressure against a portion of the stomach, causing the patient to experience feelings of fullness.

2. 3. The procedure of paragraph 17, wherein the positioning step includes securing the bag to tissue below the Z line of the gastroesophageal junction region.

24. The procedure of paragraph 17, in which at least a part of the bag is disposed within the prosthesis.

25. The procedure of paragraph 17, in which the prosthesis is extended from a distal portion of the bursa.

26. The procedure of paragraph 1, in which the positioning step positions the proximal opening of the prosthesis in a position between a fundus of the stomach and the pylorus

27. The procedure of paragraph 1, wherein the positioning step positions the proximal opening of the prosthesis adjacent to the esophagus and positions the distal opening of the prosthesis adjacent to the pyloric sphincter.

28. The procedure of paragraph 1, in which the prosthesis includes a distal tube, and in which the positioning step includes positioning the distal tube through the pylorus, and in which the procedure includes causing the food material to pass from the prosthesis in the distal tube.

29. The method of paragraph 1, wherein the distal tube includes a first portion, a second portion, and a tether connecting the first and second portions, and wherein the positioning step includes positioning the distal tube in such a manner that the strap is adjacent to Vader's vial.