Patent Publication Number: US-2015088048-A1

Title: Intragastic implant devices

Description:
This application is a continuation of International Patent Application No. PCT/US2008/004207, flied Mar. 31, 2008 and designating the United States, which International application claims the benefit of U.S. Provisional Patent Application No. 60/908,902, filed Mar. 29, 2007, the entire disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention disclosed herein enables anchoring of therapeutic or diagnostic devices, such as for example bariatric sleeves, within the stomach with a relatively stable position and orientation. The system can supplement such current weight reduction technology as intragastric balloons and gastric banding as well as bariatric surgeries such as Roux-en-Y gastric bypass. 
     Roux-en-Y gastric bypass has proven an especially effective weight-reduction surgery, likely because it acts through multiple mechanisms. By reducing the effective size of the stomach the surgery reduces oral intake&#39;s exposure to gastric digestive juices and promotes early satiety by leaving a smaller residual stomach to fill. In bypassing the ampulla of Vater and a length of proximal small intestine the surgery delays the action of biliary and digestive enzymes on food particles while reducing the length of small bowel exposed to nutrients. 
     Current bariatric surgery procedures, while proven effective and beneficial for patients, are highly invasive, result in permanent changes to the patient&#39;s digestive tract, and carry a substantial risk of surgical complications or death. As a consequence of the risk, bariatric surgery is generally indicated only for the morbidly obese, body mass index (BMI) 40 or greater, or for the moderately obese (BMI&gt;35) with substantial obesity-related comorbidities such as diabetes and hypertension. 
     BRIEF SUMMARY OF THE INVENTION 
     Prior to this invention, gastric anchoring methods have required stapling, suturing, or other modification of the anatomy to hold a device in place. In contrast, the invention described herein exploits asymmetric geometry of gastric anatomy to maintain a gastric implant in a relatively fixed position within the gastrointestinal tract without attachment to the gastric wall. Specifically, the present invention is directed to a gastric implant that comprises an intragastric anchor and a therapeutic or diagnostic device coupled to the anchor. The intragastric anchor of the invention limits the movements of any device attached to it to the displacement available to the anchor within the stomach. In one embodiment, the intragastric anchor has an elongate shape extending along the long axis of the stomach substantially from the antrum to the fundus such that displacement of the anchor along the long axis due to gastric contractility or other causes is limited by the gastric anatomy of the fundus and pylorus. Similarly, the elongate anchor is configured to be longer than the transverse width of the stomach and thus too long to be flipped end over end within the stomach by gastric contractility. Thus, the intragastric anchor provides a relatively stable platform on which to anchor bariatric or other therapeutic or diagnostic devices. Once deployed within the stomach, the anchor is configured to be larger than the pyloric valve to prevent its passing out of the stomach and into the small bowel. This configuration enables the intragastric anchor to maintain a relatively fixed position and orientation within the gastrointestinal tract. Additionally, an extension from the anchor into the esophagus may be present, which defines a plane such that the anchor may also prevent rotation within the stomach. The present invention is further directed to a method for anchoring as therapeutic device or a diagnostic device within the stomach in a relatively fixed position, that is with a relatively stable position and orientation, while being free from attachment to the stomach wall, the method comprising positioning an anchor according to the invention in the stomach of a patient between the fundus and the pyloric valve; and coupling a therapeutic device or a diagnostic device to the anchor. 
     Having secured the anchoring implant within the stomach, any number of devices may be attached to it. In one embodiment, the device is a therapeutic device. For example, a bariatric sleeve may be secured to extend from the esophagus to the jejunum, supported by a geometrically-fixed intragastric anchor. Similarly, a jejunal bypass sleeve extending from the pylorus into the jejunum may be supported by such an anchor. Also similarly, devices restricting gastric inflow and/or outflow may be supported by an intragastric anchor. Alternatively, a removable esophageal stent deliberately designed for sliding contact within the esophagus, so as to avoid hyperplastic tissue ingrowth may be supported by the intragastric anchor. The combination of elongate intragastric anchor and sliding esophageal stent improves upon conventional stenting by avoiding the tendency of esophageal stents to migrate or to become unremovable through hyperplastic tissue ingrowth and scarring. 
     Similarly, diagnostic devices, such as for example a pH sensor, may be supported within the gastrointestinal tract by an intragastric anchor. By way of example, when configured to maintain a pH sensor within the esophagus, an intragastric anchor may include an esophageal extension, extending from the body of the anchor through the lower esophageal sphincter and into the esophagus, to support the sensor in a relatively fixed position within the esophagus. Since, the esophagus serves to introduce oral intake into the stomach, the pH sensor is preferably held relatively apposed to the esophageal wall to avoid luminal blockage. Furthermore, since the intragastric anchor will move in a restricted fashion during normal gastric contractility and likewise move the pH sensor affixed to it, the pH sensor is preferably slidably coupled to the esophagus by an atraumatic sliding apposition structure. Regular sliding along the esophageal wall reduces the possibility of hyperplastic tissue ingrowth, minimizes pressure on healthy mucosa, and enhances the removability of the sensor. The combination of elongate intragastric anchor and sliding apposition structure improves upon stenting, stapling, suturing, and other fixation methods for implanted diagnostic devices by avoiding the tendency of such implants to migrate or to become unremovable through tissue ingrowth and scarring. 
     One application of the intragastric anchor revolves around bariatric therapy. A specific implementation described in this disclosure mimics the mechanisms by which Roux-en-Y gastric bypass surgery is thought to operate while avoiding surgical changes to the patient&#39;s anatomy. An anchored bariatric sleeve reduces the effective volume of the stomach and provides a mechanism for early satiety through stimulation of stretch receptors in the fundus, reduces exposure to gastric juices by bypassing the stomach, delays exposure to digestive enzymes by bypassing the ampulla of Veter, and reduces nutrient absorption by bypassing a section of the small bowel. 
     Configured to secure an anchored bariatric sleeve within the gastrointestinal tract, the intragastric anchor supports the proximal opening of the sleeve in the esophagus proximal to the gastroesophageal junction such that it does not migrate into the stomach. Since the intragastric anchor will move in a restricted fashion during normal gastric contractility and will likewise move the bariatric sleeve affixed to it, the proximal opening of the anchored bariatric sleeve is preferably slidably coupled to the esophagus by an atraumatic sliding esophageal seal. The combination of elongate intragastric anchor and sliding esophageal seal improves anon stenting, stapling, suturing, and other fixation methods h avoiding the tendency of gastrointestinal tract implants to migrate or to become unremovable through tissue in growth and scarring. 
     One embodiment of an anchored bariatric sleeve device includes a substantially axially noncompliant structure extending from the intragastric anchoring body into the esophagus. The relatively axially noncompliant esophageal extension supports the proximal opening of the bariatric sleeve and the sliding esophageal seal. The distal section of the bariatric sleeve extends into the small bowel. Such a device effectively duplicates the multiple therapeutic mechanisms of the Roux-en-Y gastric bypass. 
     The anchored bariatric sleeve is delivered to the target site either via a prepositioned guidewire or configured as an overtube slid over an endoscope. The device may include multiple radiopaque markers along its length to aid deployment under fluoroscopic guidance. For example, markers are placed at the distal end of the jejunal bypass tube, at the antral (distal) end of the intragastric anchor, at the fundal (proximal) end of the intragastric anchor, and at the sliding esophageal seal. 
     In a first specific aspect of the present invention, an intragastric implant comprises an elongate anchor adapted to extend substantially from the fundus to the pyloric valve in a patient, and a therapeutic or diagnostic device, such as a bariatric sleeve, coupled to the anchor. By “extends substantially from the fundus to the pyloric valve” is meant that the anchor may reach from the proximal stomach in the fundal area to the distal stomach in the antral area. The anchor may be shorter than the stomach but generally reaches from one end to the other, so that the ends sit in the antrum and fundus but do not necessarily contact the pylorus or the end of the fundus. The elongate anchor will usually be adapted to remain positioned in the stomach without the need for suturing, stapling, or other forms of attachment. The length and geometry of the anchor will typically be selected to assure that the anchor remains within the stomach without being ejected through the pyloric valve or otherwise adversely affecting the patient. The therapeutic or diagnostic device will be either fixedly or movably coupled to the anchor, and may be coupled at one or more points. In the case of a bariatric sleeve, the bariatric sleeve will be configured to act in a manner similar or analogous to the Roux-en-Y gastric bypass, typically having a central passage with an upper or proximal opening positionable in the esophagus and a lower or distal outlet positionable in the intestines, or in some instances within the stomach. The bariatric sleeve may have a variety of particular configurations: it may be either rigid, flexible, or have portions of each it may be either straight, curved, or have other combination geometries; and/or it may comprise nestable, interlocking or hinged links in order to have a shape-lock configuration which facilitates introduction and subsequent reconfiguration within the stomach. The elongate anchor will usually have upper and lower atraumatic ends, where the atraumatic end may be a bulbous geometry, a looped structure, or the like. 
     The bariatric sleeve will usually have a resilient sliding seal at its proximal end, which is adapted to slide against or slidably engage the inner wall of the esophagus. The sliding seal may be an inflatable balloon or cull structure, or it may be a resilient flared structure, or it may be a stented structure to provide a resilient opening force, or the like. Usually, the bariatric sleeve will also slidably extend through the pyloric valve so that both the upper and lower ends of the sleeves may move within the gastroesophageal junction and pyloric valve as the stomach changes positions. 
     In another aspect of the present invention, a method for treating obesity comprises positioning, an anchor in the stomach of a patient. The anchor will typically be positioned between the fundus and the pyloric valve and will usually be free from attachment to the stomach wall. A bariatric sleeve is coupled to the anchor, and the anchor positions an upper opening of the sleeve in the esophagus and a lower outlet of the sleeve in the intestines or the stomach. The sleeve is slidably received through the gastroesophageal junction and the pyloric valve, and the opening of the sleeve is preferably slidably disposed against a wall of the esophagus to inhibit food bypass. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic view of an anchored bariatric bypass implant of the invention illustrating the major components. 
         FIG. 2  is a view of an inflatable embodiment of an anchored bariatric implant in a sectioned stomach and small bowel. 
         FIG. 3A  is a view of a sectioned stomach and small bowel with gastroscope, guidewire and pyloric and gastroesophageal junction marker clips. 
         FIG. 3B  is a view of a sectioned stomach and small bowel with a sheathed anchored bariatric implant on a guidewire. 
         FIG. 4A  is a view of a sectioned stomach with an anchored bariatric sleeve including a widened reservoir in the compressed state. 
         FIG. 4B  is a view of a sectioned stomach with an anchored bariatric sleeve including a widened reservoir in the expanded state. 
         FIG. 5A  is a view of a sectioned stomach with a linked intragastric anchor in a relaxed state. 
         FIG. 5B  is a view of a sectioned stomach with a linked intragastric anchor in a stiffened state. 
         FIG. 5C  is a sectioned view of a balloon-tensioned linked intragastric anchor detailing link and balloon structure with balloons deflated. 
         FIG. 5D  is a sectioned view of a balloon-tensioned linked intragastric anchor detailing link and balloon structure with balloons inflated. 
         FIG. 6A  is a sectioned view of a sliding esophageal seal with a curved contact surface. 
         FIG. 6B  is a sectioned view of a sliding esophageal seal with a tapered wiper contact surface. 
         FIG. 6C  is a sectioned view of a sliding esophageal seal with a self-expanding scaffold. 
         FIG. 7A  is a view of a sectioned stomach with an anchored compliant gastric outflow restrictor. 
         FIG. 7B  is a view of a sectioned stomach with a sectioned anchored compliant gastric outflow restrictor. 
         FIG. 8A  is a view of a sectioned stomach with a closed pyloric sphincter and an anchored spherical gastric outflow restrictor. 
         FIG. 8B  is a view of a sectioned stomach with a open pyloric sphincter and an anchored spherical gastric outflow restrictor. 
         FIG. 9  is a view of a sectioned esophagus with a sinusoidal sliding esophageal seal. 
         FIG. 10  is a view of a sectioned, esophagus and stomach with a sliding esophageal stent supported by an intragastric anchor. 
         FIG. 11  is a view of a sectioned stomach with a gastric inflow restrictor supported intragastric anchor. 
         FIG. 12A  is a sectioned view of a balloon-tensioned linked intragastric anchor detailing link and balloon structure with balloons deflated. 
         FIG. 12B  is a sectioned view of a balloon-tensioned linked intragastric anchor detailing link and balloon structure with balloons inflated. 
         FIG. 13  is a view of a sectioned esophagus and stomach with a pH sensor and sliding apposition structure supported by an intragastric anchor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The intragastric anchor depicted in  FIG. 1  includes a longitudinal anchoring body  10  that extends along the longest gastric axis from the antrum to the fundus. The anchoring body ( 10 ) may be substantially linear as shown in  FIG. 1  such that it somewhat straightens the natural curvature of the stomach when deployed, or as shown in  FIG. 11  the anchoring body ( 112 ) may be curved or bent to substantially follow the natural curvature of the stomach. Referring again to  FIG. 1 , the length of the anchoring body  10  is greater than the stomach&#39;s largest flattened transverse diameter, thus preventing its end-to-end rotation within the stomach during normal gastric contractility. Length L should normally be in the range of from about 15 cm to about 50 cm, preferably from about 20 cm to about 40 cm, more preferably approximately 30 cm. 
     Referring to  FIG. 1  blunted ends of the anchoring body prevent trauma to tissue as the anchor is pushed back and forth within the stomach by the antrum&#39;s grinding peristalsis. The blunt shape of the fundal bulb  11  distributes the substantial force exerted upon the fundus as the antrum squeezes the distal portion of the anchoring body and propels it proximally towards the fundus. The antral bulb  12  serves a similar force distribution purpose within the antrum and also serves to keep the anchoring body  10  from passing through the pyloric valve and into the small bowel. The antral bulb diameter should normally be in the range of from about 20 mm to about 50 mm, preferably from about 25 mm to about 40 mm, more preferably approximately 30 mm. An anchoring body configured to maintain its orientation within the stomach may serve to deliver drugs to specific areas of the stomach. By way of example the fundal bulb may include a drug-eluting coating with a drug specifically targeted to the fundus and the antral bulb may include a drug-eluting coating with a drug specifically targeted to the antrum. 
     The anchoring body may be implemented as a rigid, or semirigid inflatable balloon structure. Referring to  FIG. 2 , in order to accommodate relatively high pressures in the main section of the anchoring body  20  and in the fundal bulb  21  and antral bulb  22 , the anchoring body  20  may be formed of tubular sections shaped into appropriate dimensions for their respective functions. By way of example, rather than forming a fundal bulb with a large pressurized cross section, a relatively small diameter tubular balloon may be, as in  FIG. 2 , shaped into a fundal bulb  21  with a large sweeping shape and a relatively large radius of curvature so as to produce a relatively small surface pressure in the fundus. Also by way of example, rather than forming an antral bulb with a large pressurized cross-section, a relatively small diameter tubular balloon may be, as in  FIG. 2 , shaped into an antral bulb  22  with a curvature that at least partially wraps around and accommodates the bariatric sleeve  23  and with a sufficiently large diameter to prevent the antral bulb&#39;s passing through the pyloric valve while also producing a relatively small surface pressure on the antrum and pylorus. 
     Since an unintentional deflation resulting in a intragastric device passing through the pylorus and into the small bowel might cause an obstruction,  FIG. 2  shows a rigid element  28  whose length dimension is small enough to pass through the esophagus and into the stomach but that is long enough not to pass beyond the duodenal bulb or through the tight bends of the relatively fixed duodenum. The rigid element may also serve as an attachment point for an esophageal extension  24 . Struts  27  may extend from the rigid element to support a sliding esophageal seal  26 . The rigid element  28  should normally be approximately 5 cm to 20 cm in length, preferably approximately 10 cm, and may be included in any suitable portion of the intragastric anchor. 
     The intragastric anchor serves to anchor therapeutic or diagnostic devices, such as for example bariatric sleeves, in a relatively stable position within the gastrointestinal tract. Employed as an anchor for a bariatric sleeve running from the esophagus to the small bowel, the anchoring body in  FIG. 1  is affixed to and supports at least a portion of the compliant intragastric section of the bariatric sleeve  13  as it runs along the anchoring body, thus preventing it from kinking. The antral bulb  12  may run alongside the distal intragastric section of bariatric sleeve  13  or, as shown in  FIG. 2 , the antral bulb  22  may partially or completely surround the bariatric sleeve  23  to maintain a patent sleeve lumen proximal to the pylorus. Referring again to  FIG. 1 , the anchoring body  10  leaves a substantial portion of the bariatric sleeve&#39;s surface exposed to the stomach such that peristalsis may squeeze it against the anchoring body and drive food contents distally through the pyloric valve and into the small bowel. A portion of the bariatric sleeve  13  may be configured to be sufficiently flexible for the pyloric valve to pinch it shut when closed. The anchoring body supports the proximal opening  15  of the bariatric sleeve and a sliding esophageal seal  16  via an esophageal extension  14  reaching from the anchor into the esophagus proximal to the lower esophageal sphincter. The esophageal extension transmits the forces of esophageal peristalsis to the anchoring body  10 , thus resisting the tendency of peristalsis to push the opening of the bariatric sleeve into the stomach. Since normal stomach contraction and peristalsis will rock and shift the anchoring body within the stomach within a certain range, the esophageal extension must be long enough to prevent the sliding seal from being drawn into the stomach by these motions. The esophageal extension should normally be about 5 cm to about 40 cm long, preferably about 10 cm to about 30 cm long, more preferably approximately 20 cm in length. Since the esophageal extension and anchoring body together define a plane, the esophageal extension also saves to resist any tendency of the anchoring body to rotate around its long axis within the stomach. Such rotation might twist or kink the bariatric sleeve to cause a blockage. 
     In a presently preferred embodiment, the esophageal extension comprises at least one and more preferably at least three struts connecting the anchoring body to an esophageal seal. In another presently preferred embodiment, the struts are configured to have a long aspect ratio such that they are relatively rigid along the esophageal axis but flexible in the transverse plane such that the lower esophageal sphincter may deflect the struts sufficiently to seal normally while retaining sufficient axial rigidity to support the esophageal seal against esophageal peristalsis. As is shown in  FIG. 2 , the esophageal extension may also maintain in a relatively stable position a perforated or otherwise gastric juice-permeable section  29  of the bariatric sleeve. In a preferred embodiment, the perforated section  29  is maintained just distal to the gastroesophageal junction to mimic the gastric juice exposure of a surgically-created gastric pouch in that location. The esophageal extension may be implemented in many ways within the scope of this invention. In a fluid-inflatable embodiment of the anchored bariatric sleeve depicted in  FIG. 2 , the esophageal extension  24  may comprise one or more gas- or liquid-pressurized sinus  27  connecting the anchoring body to the esophageal seal. Similarly the esophageal extension may comprise one or more non-inflatable elastomeric struts with axial stillness and transverse flexibility. In another embodiment of the esophageal extension, an axially stiff but radially flexible mesh may take the place of the struts to support the esophageal seal while allowing radial compression of the lower esophageal sphincter. Alternately, in an implementation of a temporary gastric sleeve implant, an esophageal extension may completely or partially stent open the lower esophageal sphincter. As such, the esophageal extension may have significant radial as well as axial stiffness. 
     In order to mimic the early satiety mechanism of various restrictive bariatric surgical procedures, a bariatric sleeve  40  as shown in  FIG. 4A  may include a widened reservoir  41  just above the anchoring body  42  and a narrowed section  43  distal to the reservoir. Similar to the perforated section  29  of the bariatric sleeve shown in  FIG. 2  the widened reservoir  41  may be perforated or otherwise made permeable to gastric juices so as to mimic the reduced exposure to gastric juices caused by stomach volume reducing surgeries such as Roux-en-Y gastric bypass. The narrowed section limits direct flow-through of solid oral intake into the duodenum and is analogous to the small-diameter gastricojejunostomy created in Roux-en-Y gastric bypass. Again referring to  FIG. 4A , the anchoring body  42  is configured with a protrusion  44  that substantially fills the cardia portion of the stomach immediately distal to the lower esophageal sphincter and substantially compresses the empty reservoir  41 . As the patient eats and the reservoir tills and expands as shown in  FIG. 4B , the cardia is expanded while the anchoring body  42  is partially displaced from the cardia by the expanding reservoir  41 , causing the fundal bulb  45  to press laterally outwards into the fundal wall. The reservoir normally has a volume of approximately 5 cc to 60 cc, preferably approximately 15 cc to 40 cc more preferably approximately 30 cc. Actions on the cardial and fundal walls stimulate stretch receptors and serve as biofeedback mechanisms to promote satiety. 
     Since normal stomach contraction and peristalsis will rock and shift the anchoring body within the stomach within a limited range, the proximal opening of the bariatric sleeve is best served by a sliding seal which can slide back and forth within the esophagus following the motions of the anchoring body while retaining the ability to direct most food particles into the proximal opening of the bariatric sleeve. The sliding seal may be implemented in a number of ways. As shown in  FIG. 2 , the sliding seal  26  may take the form of a rigid or semi-rigid inflatable smooth-edged structure that approximates the proximal opening of a gastric sleeve to the esophageal wall without fixing it in position and stays in light contact with the esophageal mucosa without enough force, to damage the mucosa. Struts  27  support the sliding seal  26  against esophageal peristalsis and may serve as conduits for inflation fluid or gas, coupling the seal with the inflatable anchoring body  20 . As shown in  FIG. 9 , an inflatable sliding seal  90  may be wavy or sinusoidal in form such that its diameter may expand or compress to accommodate a range of esophageal diameters as it holds open the proximal end of bariatric sleeve  92 . Struts  91  support the sliding seal  90  axially against peristaltic esophageal contractility while allowing sufficient radial flexibility for the seal to accommodate a range of esophageal diameters. Alternately as shown in  FIGS. 6A and 6B , the sliding seal may take the form of a compliant elastomeric wiper whose shape and durometer are selected for low friction and low normal force imparted to the esophageal wall while accommodating a range of esophageal diameters. The sliding seal  60  shown in section view in  FIG. 6A  holds open the proximal end of bariatric sleeve  61  and includes a compliant elastomeric sliding surface  62  radiused to present smooth curving edges to the esophagus both whether sliding proximally or distally. The sliding seal  63  shown in section view in  FIG. 6B  includes a tapered compliant elastomeric sliding surface  64  configured as a low-friction wiper. Similarly as shown in  FIG. 6C , a proximal opening of the bariatric sleeve  67  may be configured for sliding with a radiused proximal edge  65  and in be propped open and held slidably apposed to the esophageal will by a self-expanding scaffold  66  made of polymer, nickel-titanium alloy, a stainless steel alloy, or the like. Performance of most embodiments of the sliding seal may be enhanced with the addition of a friction-reducing surface such as a hydrophilic coating, parylene coating, or the like on the seal&#39;s mucosa-contacting surfaces. The coating or seal material itself may also be drug-eluting for targeted delivery in the esophagus. 
     One aspect of the intragastric implant of the invention is directed to an anchored bariatric sleeve delivery system. In one embodiment, the anchored bariatric sleeve is delivered in a compacted state, contained between an outer constraining catheter and an internal guidewire catheter. The delivery system and the gastric implant may include radiopaque markers at various points along the length of the system to aid in fluoroscopic visualization of both implant and delivery system. The radiopaque markers enable proper positioning and timing of release of various sections of the implant within the GI tract. 
     A preferred sequence of delivery steps for the anchored bariatric sleeve is as follows: 1) endoscopic marking of anatomical structures and guidewire placement, 2) fluoroscopic deployment of jejunal bypass sleeve, and 3) fluoroscopic placement and deployment of anchor structure in stomach. 
     The initial phase begins with the standard intubation of the patient with an gastroscope. As shown in  FIG. 3A , under direct visualization via the gastroscope the endoscopist then creates fluoroscopic anatomy visualization aids by attaching an endoscopic clip to the mucosa of the pylorus as a marker  301  and another endoscopic clip to the mucosa of the gastroesophageal junction as is marker  302 . Advancing the gastroscope past the pylorus, the endoscopist then delivers a stiff guidewire  311  into the small bowel, leaving it in place and removing the gastroscope. 
     Having prepared the entry path, the endoscopist switches to fluoroscopy and as shown in  FIG. 3B  introduces the anchored bariatric sleeve, packaged between a constraining catheter  305  and a pushing catheter  306  with a central guidewire lumen and atraumatic tip  307 , into the stomach and duodenum over the guidewire, watching the fluoroscopic image to confirm that the distal sleeve marker  303  and antral bulb marker  304  have moved distally of the pylorus marker clip  301 . The constraining catheter  305 , visible with as distal radiopaque marker  308 , is then withdrawn sufficiently to expose and release the compressed jejunal bypass sleeve  312  (approximately to the antral bulb marker  304 ) while the anchored bariatric sleeve is held in position by resistance from the pusher catheter  306 . The guidewire is then removed and water is flushed through the guidewire lumen of the pusher catheter into the device and into the jejunal bypass sleeve  312  to help it extend past the ligament of Treitz (peristalsis can complete the job). 
     Following deployment of the jejunal bypass sleeve  312 , the anchor portion of the anchored bariatric sleeve is positioned within the stomach by withdrawing the entire device until the antral bulb marker  304  is proximal to the pyloric marker  301  while the fundal bulb marker  309  is still distal to the gastroesophageal junction marker  302 . The constraining catheter  305  is then withdrawn sufficiently to expose the fundal bulb marker  309  (but not yet releasing, the device from the pusher catheter  306 ). Confirming that the antral bulb marker  304  is still proximal to the pyloric clip  301 , the intragastric anchor is deployed such that it extends from the antrum to the fundus with the antral and fundal bulbs expanded into blunt, atraumatic shapes too large to pass through the pyloric valve. The esophageal seal, fluoroscopically visible with its own radiopaque marker  310 , is then positioned in the esophagus proximal to the gastroesophageal junction clip  302  and released from the pusher  306  and constraining  305  catheters. Movement of the anchored bariatric sleeve is now constrained only by the shape of the intragastric anchor and esophageal extension. 
     An alternate embodiment of an intragastric anchor of the invention comprises a rigidizable structure. The rigidizable structure comprises links that transition between substantially flexible and substantially rigid configurations. The straightening and stiffening (rigidizing) process may be reversible or non-reversible, depending upon the design and the use for which the intragastric anchor is intended. Optionally, the rigidizable structure will further comprise a non-reversible rigid element. One example of an intragastric anchor comprising a rigidizable structure, as shown in  FIGS. 5A ,  5 B,  5 C and  5 D, employs interlocking links to form a connecting shaft  500  between antral bulb  501  and fundal bulb  502 . Connecting shaft  500  is configured to be reversibly substantially flexible and curved, as shown in  FIG. 5A , or substantially rigid and straight, as shown in  FIG. 5B . in the substantially flexible configuration, the intragastric anchor may traverse the curved path of the esophagus from the mouth to the stomach. Once converted to the substantially rigid configuration in the stomach, the intragastric anchor may support any number of therapeutic or diagnostic devices. Individual links  503  are held together by a central tether  505  which conveys tension to compress springs  508  and engage adjacent links.  FIGS. 5C and 5D  show an intragastric anchor having rigidizable links  503  separated by springs  508  and strung together on tether  505 . In this embodiment, links  503  are configured with nestable male  506  and female  507  ends with relatively tight-fitting cylindrical sections that constrain adjacent links to a single axis when tether  505  pulls the links together. As depicted in  FIGS. 5A and 5C , links  503  are normally disengaged from one another such that adjacent links may angle with respect to one another thereby imparting flexibility to the entire connecting shaft  500  linkage. As shown in  FIGS. 5B and 5D , when engaged links  503  are constrained to be substantially collinear thus creating a substantially rigid connecting shaft  500 . In a preferred embodiment, tether  505  may contain a central lumen used to fill an inflatable embodiment of the antral bulb  501  and fundal bulb  502 . Inflation of the bulb balloons  511  and  512  as shown in  FIGS. 5C  (uninflated) and  5 D (inflated) creates atraumatic bulb surfaces and straightens and rigidizes the structure. Bulb balloon inflation creates the tension in tether  505  required to straighten and rigidize connecting shaft  500  by retracting the tether from flared cup end links  509  and  510 , In the uninflated state, flared cup end links  509  and  510  may contain compliant, pressure-expanding balloons or the flared cup end links may contain folded, pleated, or wrapped noncompliant or semi-noncompliant balloons connecting to tether  505  and configured to tension the tether when inflated. The nesting and stiffening (rigidizing) process is entirely reversible, 
     The specific embodiment of the bulb balloons  511  and  512  shown in  FIGS. 5C and 5D  contains an axial member  513  connecting opposing faces of the balloons. Axial member  513  transmits tension from the outer balloon face to the inner face and to the tether  505  when the balloon is expanded as well as serving as a location for an internal fill port  514  for the balloon. The outer end of axial member  513  may also serve as a site for a detachable pressure connection and valve  515  through which the balloons are inflated by an external source. 
     To prevent a linked intragastric anchor from passing into the small bowel upon an inadvertent balloon deflation or relaxation of the connecting shaft  500  and possibly causing an obstruction, a rigid element  504  as shown in  FIGS. 5A and 5B  and similar in function to rigid element  28  in  FIG. 2 , might be included in the connecting shaft or any suitable portion of the intragastric anchor. The rigid element  504  has a length dimension that is small enough to pass through the esophagus and into the stomach but is long enough not to pass beyond the duodenal bulb or through the tight bends of the relatively fixed duodenum. The rigid element  504  should normally be approximately 5 cm to 20 cm in length, preferably approximately 10 cm. 
       FIGS. 12A and 12B  show an alternate embodiment of a linked intragastric anchor in which concentric hinged rigidizable linkages  1201  and  1202  may be shifted with respect to one another to transition the connecting shaft  1200  from a substantially flexible state to a substantially rigid state. As shown in  FIG. 12A , when in the flexible state outer binged linkage  1201  and inner hinged linkage  1202  are aligned with their respective hinges in approximately the same axial location. Spring  1203  maintains that approximate alignment by maintaining substantial contact between outer linkage shoulder  1204  and inner linkage shoulder  1205 . 
     As is shown in  FIG. 12B , inflation of tensioning balloon  1206  translates inner hinged linkage  1202  with respect to outer hinged linkage  1201  and compresses spring  1203 . Putting the non-hinged portions of inner linkage  1202  inside outer hinge points  1207  and the non-hinged portions of outer linkage  1201  over inner hinge points  1208  both straightens and stiffens connecting rod  1200 . 
     The straightening and stiffening (rigidizing) process is entirely reversible. Deflation of tensioning balloon  1206  allows spring  1203  to translate inner hinged linkage  1202  with respect to outer hinged linkage  1201 , returning inner hinge points  1207  and outer hinge points  1208  to the flexible overlapping position of  FIG. 12A . 
     Because the hinges of inner hinged linkage  1202  and outer hinged linkage  1201  must operate within approximately the same plane in order to transition from the rigid state to the flexible state, the linkages are preferably rotationally keyed to one another along their respective longitudinal axes while allowing free longitudinal sliding. This may be accomplished by employing links with a rectangular cross section or through an other suitable keying means. 
     Another aspect of the intragastric implant of the invention is directed to an anchored gastric outflow restrictor. As shown in  FIG. 7A , an intragastric anchoring body  700  may be employed to effect delayed gastric emptying by serving as a supporting platform for as compliant gastric outflow restrictor  701 . The outflow restrictor extends from the distal end of the anchoring body, though the pylorus, and into the small bowel. The outflow restrictor is configured to be compliant such that it compresses radially when the pyloric sphincter closes and expands radially when the pyloric sphincter opens, thus maintaining substantial contact with the pyloric mucosa and obstructing and limiting the exit of chyme into the duodenum from the stomach. As antral peristalsis combines with the relaxing of the pyloric sphincter, chyme must squeeze between the outflow restrictor and sphincter to exit the stomach. Thus, the compliance of outflow restrictor  701  may be tuned to allow chyme to exit the stomach at greater or lesser peristaltic pressure. The outflow restrictor  701  may be constructed in a number of different ways including but not limited to braided polymer or metallic fiber, skinned open cell elastomeric foam, silicone gel in an elongate low-durometer elastomeric container, and closely spaced radial elastomeric fins. In one presently preferred embodiment, outflow restrictor  701  is comprised ole cylindrical braided polymer mesh is embedded in a low-durometer silicone rubber to create a smooth hollow nonporous tubular structure with open end  702 , a sealed proximal end  703  attached to an intragastric anchoring body  700 , and an uncompressed diameter of approximately 15 mm to 35 mm, preferably approximately 25 mm. The rubber-encased braided tube may flex, expand, and compress without wrinkling or creasing, thus providing an excellent sealing surface when apposed to the pyloric sphincter. Compliance of a braided mesh outflow restrictor may be adjusted by increasing or decreasing the diameter of the braided fibers or by modifying the braid angles. 
       FIG. 7B  shows, in another embodiment, an intragastric anchor  710  supporting a compliant outflow restrictor  711 . Since anchor  710  does not span the long gastric axis and, thus, can be moved out of the antrum by gastric contractility, outflow restrictor  711  is sufficiently long to maintain at least a distal portion  716  within the small bowel. Outflow restrictor  711  should normally be approximately 20 cm to 80 cm long, preferably approximately 30 cm to 50 cm, more preferably approximately 40 cm. 
     Within the scope of this invention, intragastric anchor  710  may be implemented as a balloon or a series of balloons, a mechanical linkage configured for radial expansion, a polymer or metallic shape-memory structure, or any suitable means. The anchor should normally have a rounded, atraumatic envelope approximately 2.5 mm to 50 mm in diameter, preferably approximately 35 mm in diameter, and may be spherical, oblong, cylindrical, ovoid, or any suitable shape. The anchor may include one or more deployable anchoring bodies such as balloons. By way of example, it may be advantageous to include a balloon mounted on either end of a liquid-inflated anchor&#39;s rigid element so as to reduce the overall inflated balloon volume and, thus, reduce the anchor&#39;s weight. In a presently preferred embodiment, intragastric anchor  710  is oblong in shape and comprises an assembly including a balloon  712  made of substantially noncompliant material and which substantially covers a rigid element  713  whose length dimension is small enough to pass through the esophagus and into the stomach but is long enough not to pass beyond the duodenal bulb or through the tight bends of the relatively fixed duodenum. The rigid element may also serve as attachment point for an inflation valve  714 , which may be recessed within a concealing feature  717 , and as a manifold for distributing inflation fluid to one or more balloons  712  through one or more inflation ports  715 . The rigid element  713  should normally be approximately 5 cm to 20 cm in length, preferably approximately 10 cm, and may be included in any suitable portion of the intragastric anchor. 
     In a further preferred embodiment, outflow restrictor  711  comprises a silicone rubber coated tubular braid  718  which extends over balloon  712  and terminates under a concealing feature  717 , creating a smooth unbroken surface between the outflow restrictor and larger-diameter intragastric anchor  710 . Tubular braid  718  may serve to limit the expansion of a compliant or semi-compliant anchor balloon  712 . 
     Outflow restrictor  711  may include one or more relatively rigid sections  719  which resist compression by peristalsis relative to the rest of the outflow restrictor, and thus may be driven downstream in the small bowel by peristaltic contractility, thereby tending to pull the intragastric anchor distally into the antrum and against the pyloric sphincter. In a presently preferred embodiment, rigid section  719  is a section of thickened wall built up on the inner diameter of outflow restrictor  711  with silicone rubber, is located on its distal end, and serves to terminate tubular braid  718  and provide an atraumatic distal tip. 
       FIGS. 8A and 8B  show an alternate embodiment of an intragastric anchor  80  supporting and locating a gastric outflow restrictor  81 . The outflow restrictor diameter should normally be in the range of approximately 20 mm to 50 mm, preferably approximately 25 mm to 40 mm, more preferably approximately 30 mm, to prevent its passing through the pyloric sphincter. Fundal bulb  82  couples to connecting shaft  83  to limit the movement of the restrictor along the long axis of the stomach and away from the pylorus. As stomach contents ground by gastric contractility and are partially digested by gastric juices as shown in  FIG. 8A , the limited axial movement of the outflow restrictor  81  allows only a small amount of chyme between it and the pyloric sphincter  85 . The gastric outflow restrictor is larger in diameter than the connecting shaft  83  and as shown in  FIG. 8B , during gastric emptying it will be swept distally towards the open pyloric sphincter  85  by the emptying peristaltic wave  84 , substantially sealing the pyloric sphincter and serving to limit the amount of chyme exiting the stomach and delaying gastric emptying. 
     Another aspect of the intragastric implant of the invention is directed to an anchored gastric inflow restrictor. Referring to  FIG. 11 , an intragastric anchoring body  112  may support is gastric inflow restrictor  110  that serves to slow the progress of oral intake from the esophagus to the stomach by reducing the effective diameter of the gastric inlet with a narrow section  114 . While narrowed section  114  may be located anywhere along the length of inflow restrictor  110 , a preferred embodiment locates the narrowed section at the distal end of the inflow restrictor. Inflow restrictor  110  is normally approximately between 5 cm and 30 cm in length, preferably approximately 10 cm to 20 cm long, more preferably approximately 15 cm long. Inflow restrictor  110  is maintained in sliding contact with the esophagus overlapping the gastroesophageal junction by esophageal extension  111  which supports the inflow restrictor against anchoring body  112 . Sliding seal  113  maintains a patent oral intake conduit at the proximal end of the inflow restrictor and directs most oral intake into the inflow restrictor while allowing for sliding motion proximally and distally along the esophagus as anchoring body  112  is displaced by gastric contractility and patient activity. The gastric inflow restrictor may be located entirely in the esophagus or may overlap the esophagus and stomach. The restrictor may be sufficiently compliant to compress with the closing of the lower esophageal sphincter or it may be sufficiently rigid to resist sphincter closure and at least partially stent the sphincter open. 
     Inflow restrictor  110  may include perforations  115  in its distal, intragastric portion to allow gastric juices to partially digest oral intake. 
     An intragastric anchor may support a wide range of nonbariatric therapeutic and diagnostic devices within the gastrointestinal tract. In addition to gastric inflow and outflow regulators, examples of other therapeutic devices that may be used in the present invention include, but are not limited to, drug delivery systems as are known in the art for delivering drugs directly to a targeted locale, such as the esophagus, the stomach or the small bowel (such delivery systems may be passive such as drug-eluting coatings or active such as an electronically-timed or sensor-based drug release system); radiation delivery systems for targeted radiation treatment (brachytherapy); and the like. Examples of diagnostic devices that may be used in the present invention include, but are not limited to physiologic devices for measuring the pH in various locations in the gastrointestinal tract, for measuring the pressure differential across the lower esophageal sphincter or pyloric valve, for measuring or monitoring the secretion of digestive juices from the pancreas or the gall bladder, for measuring hormones (such as, e.g., ghrelin produced by cells lining the gastric fundus), for measuring sugars, or for measuring electrolytes, and the like; imaging probes or capsules (such as an battery-powered or inductively-powered “pill camera”); and ultrasound transducer probes (for monitoring changes in, e.g., a tumor, cyst, aortic aneurism, and the like). All of the diagnostic or therapeutic systems described may be fixed in various locations in the gastrointestinal tract (such as, e.g., the esophagus, the stomach, the jejunum, the duodenum) in the present invention by an intragastric anchor. 
     As one example, as shown in  FIG. 10  an intragastric anchor  100  with esophageal extension  101  may support a removable esophageal stent  102  that is configured to allow atraumatic sliding along the esophagus so as to reduce the possibility of tissue ingrowth and minimize the pressure exerted on healthy mucosa. Sliding esophageal stent  102  may include a membrane or cover  105  to reduce the possibility of tissue ingrowth and may employ a low friction external coating such as a hydrophilic coating, parylene coating, or the like. The stent may be configured for localized drug delivery through use of a drug eluting material or coating. Similarly to the sliding seal of  FIG. 6C , sliding esophageal stent  102  may include an atraumatic beveled or rounded proximal edge  103  and distal edge  104 . 
     By way of another example, as shown in  FIG. 11 , an intragastric anchor  130  with esophageal extension  131  may support a diagnostic device  132 , such as for example a pH sensor, held substantially apposed to the esophageal wall by an traumatic sliding apposition structure  133 . The sliding apposition structure  133  provides a gentle expansion force via at least one radially compliant element  134  to allow atraumatic sliding along the esophageal wall so as to reduce the possibility of hyperplastic tissue ingrowth, minimize pressure on healthy mucosa, and enhance the removability of the sensor. Similarly to sliding stent  102 , sliding apposition structure  133  may include an atraumatic beveled or rounded proximal edge  134  and distal edge  135 , may include a low friction external coating such as a hydrophilic coating or parylene coating, and may be configured for localized drug delivery through use of a drug eluting material or coating. Sliding apposition structure  133  may be comprised of a unitary compliant polymer or elastomer or may include a polymer or metallic stenting structure.