Abstract:
Gastrointestinal implants can be used to secure thin-walled sleeves, restrictor plates, and other devices within the gastrointestinal tract. An example implant includes three elements: a stomach anchor to resist distally oriented forces; a duodenal anchor to resist proximally oriented forces; and a connector element to keep the stomach anchor fixed relative to the stomach anchor. The implant is inserted into the gastrointestinal tract with a delivery device that holds the implant in a compressed state for minimally invasive delivery until the implant is positioned properly. Upon releasing from the delivery device, the implant expands to a relaxed state across the pylorus, allowing prongs that extending outward from the stomach and duodenal anchors to engage tissue in the gastrointestinal tract. The deployed implant may also include a thin-walled sleeve that extends into the intestine from the stomach anchor, duodenal anchor, or connector element.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/217,318, filed on May 29, 2009. 
         [0002]    The entire teachings of the above application are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0003]    Obesity is associated with a wide variety of health problems, including Type 2 diabetes, hypertension, coronary artery disease, hypercholesteremia, sleep apnea, and pulmonary hypertension. It also exerts an enormous strain on the body that affects the organs, the nervous system, and the circulatory systems. Obesity rates have been rising for years in the United States, causing corresponding increases in healthcare expenditures. 
         [0004]    Curing obesity has so far vexed the best efforts of medical science. Dieting is not an adequate long-term solution for most people, especially those with body-mass indexes of over 30. Stomach stapling, or gastroplasty, reduces the size of the stomach, leading to reduced appetite and weight loss, but eventually the stomach stretches. Roux-en-Y gastric bypass reduces the size of the stomach and the length of the intestine, and leads to both weight loss and alleviation of the Type 2 diabetes common to obese patients. Although gastric bypass appears to provide a more permanent solution than gastroplasty, complication rates associated with gastric bypass are between 2% and 6%, with mortality rates of about 0.5-1.5%. 
         [0005]    Endoscopically delivered gastrointestinal implants, such as those described in commonly assigned U.S. Pat. Nos. 7,025,791 and 7,608,114 to Levine et al., incorporated herein by reference in their entireties, provide the benefits of gastric bypass without the hazards of surgery. For example, an implant may include thin-walled, floppy sleeves that are secured in the stomach or intestine with a collapsible anchor. The sleeve extends into the intestine and channels partially digested food, or chyme, from the stomach through the intestine in a manner that may cause weight loss and improve diabetes symptoms. The sleeve and anchor can be removed endoscopically when treatment is over or if the patient desires. 
       SUMMARY 
       [0006]    A gastrointestinal implant device may include a collapsible stomach anchor and a collapsible duodenal anchor coupled to each other by a radially collapsible coupling member, where the device can be secured across the pylorus. The stomach and duodenal anchors have vertices that define first and second planes, respectively, that are maintained at a substantially constant angle with respect to each other by the coupling member. For example, the coupling member may hold the first and second planes substantially parallel to each other. The example implant device may include an unsupported, thin-walled sleeve that is configured for deployment within the intestine and coupled to the stomach anchor, duodenal anchor, and/or coupling member. The stomach anchor, duodenal anchor, and/or coupling member may also be at least partially covered in a fluoropolymer such that they form a seal that channels chyme (partially digested food) from the stomach through the sleeve. 
         [0007]    An example implant device and its components can vary in size depending on whether or not the device is in a relaxed state or a compressed state. When in a relaxed state, an example stomach anchor defines a circle whose diameter is greater than about 60 millimeters. Similarly, a relaxed duodenal anchor can define a circle whose diameter is greater than about 40 millimeters. The diameter of the coupling member may be within a range of from about 10 millimeters to about 25 millimeters, and the coupling member may be within a range of about 30 millimeters to about 60 millimeters in length, e.g., about 40 millimeters long. The example device may be made of single wire, or, alternatively, the stomach anchor, duodenal anchor, and coupling member can be formed of different wires, such as nickel-titanium (nitinol) wire with a diameter of about 0.016 inches to about 0.025 inches. 
         [0008]    The stomach and duodenal anchors may comprise, respectively, stomach and duodenal prongs that extend outwards from the vertices to secure the implant device across the pylorus. When in a relaxed state, the stomach prongs form a first angle from the first plane, and the duodenal prongs form a second angle with the second plane. Each anchor may include two to six prongs, each of which may be between about 10 millimeters long and about 40 millimeters long; typically, though not necessarily, the stomach prongs are longer than the duodenal prongs. The stomach and duodenal prongs can be arranged in first and second star-shaped configurations, respectively, when viewed axially, and may be arranged so that the first and second star-shaped configurations are arranged in an alternating fashion. 
         [0009]    Each prong may include a crown adapted to engage tissue in the gastrointestinal tract, such as in the lower stomach, the pylorus, or the duodenum. The crowns of the stomach and duodenal anchors can define first and second circles whose diameters are greater than about 60 millimeters and about 40 millimeters, respectively, in a relaxed state. Each crown can have a radius of curvature of about 0.1 inch to about 0.4 inch. 
         [0010]    Gastrointestinal implant devices can be deployed in the gastrointestinal tract with a delivery device that maintains the stomach and duodenal anchors in respective collapsed states during insertion. The anchors can be configured to self-expand to respective relaxed states when released from the delivery device into the gastrointestinal tract. The stomach and duodenal anchors may expand from their respective collapsed states to their respective relaxed states in a variety of different ways. For example, at least one of the anchors may “spring open”—that is, it may form an acute angle with the coupling member in its respective collapsed state and an angle greater than the acute angle with the coupling member in its respective relaxed state. Alternatively, at least one of the anchors may “spring shut” from an obtuse angle formed with the coupling member in its respective collapsed state to an angle smaller than the obtuse angle in its respective relaxed state. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing will be apparent from the following more particular description of example 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 embodiments of the present invention. 
           [0012]      FIGS. 1A and 1B  show schematic illustrations of a transpyloric anchor before and after insertion. 
           [0013]      FIGS. 2A-2C  show schematic illustrations of a transpyloric anchor. 
           [0014]      FIGS. 3A and 3B  show perspective and plan views, respectively, of a transpyloric anchor. 
           [0015]      FIGS. 4A and 4B  show perspective and plan views, respectively, of an alternative transpyloric anchor. 
           [0016]      FIG. 5  shows a perspective view of an obesity/diabetes treatment device with another alternative transpyloric anchor. 
           [0017]      FIG. 6  shows schematic elevation views of transpyloric anchors. 
           [0018]      FIGS. 7A and 7B  show elevation and plan views of a transpyloric anchor used to secure a restrictor plate across the pylorus. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    A description of example embodiments of the invention follows. 
         [0020]    Transpyloric anchors are disclosed as alternatives to anchors provided in implants disclosed in U.S. Pat. No. 7,025,791; U.S. Pat. No. 7,608,114; U.S. Pat. No. 7,476,256; U.S. patent application Ser. No. 11/330,705; and U.S. patent application Ser. No. 11/827,674, all of which are incorporated herein by reference in their entireties. 
         [0021]      FIGS. 1A and 1B  show schematic illustrations of a transpyloric anchor  100  capable of securing a sleeve  140  for treating obesity and/or type-2 diabetes in the intestine of a patient. The sleeve  140 , which may extend into the duodenum D and jejunum J for about 60 cm or more, creates a bypass of the proximal intestine. The anchor  100  secures the proximal end of the sleeve  140  in the pylorus P, which connects the stomach S to the duodenum D, and forms a seal between either the stomach S or the pylorus P and the duodenum D. ( FIG. 1B  shows the anchor  100  forming a seal between the pylorus P and the duodenum D.) The seal ensures that most of the partially digested food, or chyme, enters the sleeve  140  and thereby avoids contact with the walls of the intestine. Thus, the anchor directs chyme from the stomach through the sleeve  140 , which may effect weight loss and the improvement in diabetes symptoms. 
         [0022]      FIG. 1A  shows the transpyloric anchor  100  in one of its undeployed configurations. A stomach anchor, or proximal member  110 , and a duodenal anchor, or distal member  130 , are folded towards the center of a connector  120 , which is strong enough to withstand pushing, pulling, stretching, and twisting forces on the transpyloric anchor  100 . Once the anchor  100  is inserted into the pylorus, the proximal and distal members  110 ,  130  spring into a deployed configuration in the direction of the arrows shown in  FIG. 1B . Once the members  110 ,  130  are deployed, the tips, or crowns, of the members  110 ,  130  engage the walls of the stomach S and duodenum D. Forces exerted by the crowns against the stomach S and duodenum D cause the anchor  100  to resist both proximally and distally directed forces, securing the anchor  100  within the pylorus. Thus, the transpyloric anchor  100  secures the sleeve  140  within the duodenum D without the use of barbs. Because the transpyloric anchor  100  does not use barbs, it may be removed simply by pulling proximally with an endoscopic device. 
         [0023]      FIGS. 2A-2D  show schematic illustrations of an alternative transpyloric anchor  200  and its deployment within the pylorus. As above, the transpyloric anchor  200  is inserted into the pylorus with folded proximal and distal members  210  and  230 , which are secured to each other with a connector  220 . In this embodiment, however, the distal member  230  is folded away from the center of the connector  220 , as shown in  FIG. 2A . When the transpyloric anchor  200  is inserted into the pylorus P, the distal member  230  deploys by springing back towards the stomach (i.e., in the direction of the arrows), which, in turn, causes crowns  234  to engage the walls of the duodenum D, as shown in  FIG. 2B . Because the distal member  230  forms an acute angle with the connector  220  in its relaxed state, the distal member  230  continues to push against the wall of the duodenum D, as shown in  FIG. 2C . The proximal member  210  can also be folded away from the center of the connector  220  either in addition or instead of folding the distal member away from the center of the connector  220 . The transpyloric anchor  200  may be removed by pulling proximally without inflicting serious or lasting damage to the patient. 
         [0024]      FIGS. 3A and 3B  show perspective and plan views, respectively, of a transpyloric anchor  300  capable of securing a sleeve in the intestine of a patient for treating obesity and/or type-2 diabetes. The transpyloric anchor  300  includes a collapsible stomach anchor, or proximal member  310  coupled to a collapsible duodenal anchor, or distal member  330  by a radially collapsible coupling member, or connector  320 . The proximal member  310  is formed of a single wire in the shape of star, with stomach prongs  312  that have tips, or crowns  314 , that engage the interior of the stomach. The number of stomach prongs  312  varies depending on the size of the device, the location of the seal, and the strength of the wire; typically, there are two to six prongs on the stomach anchor  310 . The number of crowns  314  per prong  312  may also vary. 
         [0025]    The distal member  330  is also a single wire formed into a star configuration of duodenal prongs  332 , each of which has a crown  334 . The number of duodenal prongs  332 , the number of crowns  334 , and rotational orientation of the distal member  330  with respect to the proximal member  310  depends on the wire strength and the location of the seal. For example, the proximal and distal members  310 ,  330  may be aligned in phase with each other or slightly out of phase with each other such that they press against opposite sides of the tissue separating the proximal and distal members  310 ,  330 . Arranging the proximal and distal members  310 ,  330  in phase or slightly out of phase with each other improves resistance to forces exerted along the longitudinal axis of the intestine, but may cause erosion of the tissue between the stomach and duodenal prongs  312 ,  332 . Alternatively, the proximal and distal members  310 ,  330  may be aligned out of phase with each other, as shown in  FIG. 3B , to prevent the stomach and duodenal prongs  312 ,  332  from eroding through the stomach and the duodenum. 
         [0026]    The stomach and duodenal prongs  312 ,  332  flare outwards from the proximal and distal members  310 ,  330  and trace out circular envelopes when viewed along the longitudinal axis of the anchor  300 . The envelopes have diameters that are large enough to prevent the anchor  300  from being pulled through the pylorus in either direction. For example, when relaxed, the crowns  314  of the stomach prongs  312  may trace a circle with a diameter greater than about 50 millimeters, or, more preferably, greater than about 60 millimeters, to prevent the anchor  300  from being pulled into the intestine. Similarly, the crowns  334  of the duodenal prongs  332 , when in a relaxed state, may trace a circle with a diameter of greater than about 40 millimeters to prevent the anchor from being pulled through the pylorus into the stomach. Each stomach and duodenal prong  312 ,  332  is preferably between about 10 and about 40 millimeters long, and, more preferably, between about 15 and 30 millimeters long. The stomach and duodenal prongs  312 ,  332  may bend under loading, changing the shape and size of the envelope traced by the stomach and duodenal prongs  312 ,  332 . 
         [0027]    The connector  320  maintains a fixed angle between the proximal anchor  310  and the distal anchor  330 . The proximal anchor  310  defines a plane  318  at the connection between the coupling member  320  and the proximal anchor  310 . The connection between the distal anchor  330  and the coupling member  320  defines a second plane  338 . The coupling member  320  should have sufficient stiffness linearly to maintain a fixed angle between plane  318  and plane  338 . Preferably, as shown in  FIG. 3A , this angle is zero (0) degrees such that the planes are parallel to each other and perpendicular to the axis of the transpyloric anchor. However, either of the stomach and duodenal anchors  310 ,  330  may be positioned such that their planes are angled, for example, between about 75 degrees and about 90 degrees with respect to the coupling member  320 . 
         [0028]    The connector  320  is preferably able to collapse easily and sufficiently enough for the pylorus to function. The radial force required to collapse the connector  320  diameter by 50% should be preferably no greater than about 0.5 lbs. Thus, the connector  320  may be rigid in the longitudinal direction, but radially collapsible. Here, the connector  320  is a single wire that connects the proximal and distal members  310 ,  330 . Loops  322  in the connector  320  hold the inner points of the members  310 ,  330 —that is, the vertices, or junctions  316 ,  336  between adjacent prongs  312 ,  332 . The wire segments  324  connecting the loops  322  are woven together, allowing the connector  320  to flex without comprising the connection between the proximal and distal members  310 ,  330 . 
         [0029]    When the transpyloric anchor  300  is in a relaxed state, the stomach and duodenal prongs  312 ,  332  flare outwards from the planes  318 ,  338  defined by the vertices  316 ,  336  at either end of the coupling member  320 . Depending on the configuration, the prongs  312 ,  332  may form acute or obtuse angles with the long axis of the connector  320 . In this example, both the stomach prongs  312  and the duodenal prongs  332  form acute angles with the coupling member  320 —i.e., the crowns  314 ,  334  fold towards the center of the coupling member  320  when uncompressed. Alternatively, the crowns  314 ,  334  may point away from the coupling member  320  when uncompressed; in some cases, one set of prongs  312 ,  332  may form an obtuse angle with the coupling member  320  and the other set of prongs  312 ,  332  may form an acute angle with the coupling member  320 . 
         [0030]      FIGS. 4A and 4B  show perspective and plan views, respectively, of an alternative transpyloric anchor  400 . Like the transpyloric anchor  300  shown in  FIGS. 3A and 3B , the transpyloric anchor  400  includes proximal and distal members  410 ,  430 , each of which have prongs  412 ,  432  in star configurations with crowns  414 ,  434  that engage the walls of the stomach and duodenum, respectively. A connector  420  couples the members  410 ,  430  to each other using loops  422  and wire segments  424  that connect alternating junctions  416 ,  436  of the star configurations of the proximal and distal members  410 ,  430 , respectively. Unwoven connectors  420  trade the rigidity of woven connectors (e.g., connector  320  of  FIGS. 3A and 3B ) for an improved ability to collapse to a smaller diameter. 
         [0031]      FIG. 5  shows a perspective view of an alternative transpyloric anchor  500  coupled to a sleeve  540  to form an obesity/diabetes treatment device  501 . The transpyloric anchor  500  is formed of a single loop of wire in a six-pronged star configuration, with three proximal prongs  512  spaced in an alternating fashion with three distal prongs  532 . As shown in  FIG. 5 , the proximal prongs  512  are shaped into broad wedges, which are covered to close gaps between the anchor  500  and the stomach. Crowns  514  at the ends of the proximal prongs  512  engage the stomach to prevent the anchor  500  from being pulled into the intestine. Spring force exerted by the anchor  500  causes feet  538 , which are crimped to crowns  534  with metal bands  536  at the ends of the narrow distal prongs  532 , engage the duodenum and/or pylorus. The feet  538  may engage the duodenal wall to fix the anchor  500  into position. The transpyloric anchor  500  may be coated, covered, or wrapped in sheet of material to keep chyme in the sleeve  540 , which extends into the intestine. If chyme slips between the sleeve  540  and the intestine, the effectiveness of the anti-obesity/diabetes treatment device may be reduced. 
         [0032]    In general, any transpyloric anchor may be coupled to a thin-walled sleeve that is configured to extend into the intestine. The sleeve may be made of a fluoropolymer, such as expanded polytetrafluoroethylene (ePTFE) coated or impregnated with fluorinated ethylene polyethylene (FEP), or any other suitable material, and the transpyloric anchor may be coated, covered, or wrapped in the same material used to form the sleeve. A typical sleeve is floppy and conformable to the wall of the intestine when deployed. It also has a wall thickness of less than about 0.0005 inch to about 0.001 inch and a coefficient of friction of about 0.2 or less. The sleeve and anchor covering can be a single, integrally formed piece. They can also be separate pieces, depending on whether the transpyloric anchor is partially or wholly uncovered, as long as the transpyloric anchor forms a sufficiently good seal between the sleeve and the stomach, pylorus, and/or intestine. 
         [0033]      FIG. 6  shows schematic elevations views of transpyloric anchors with a variety of different prong configurations. Prongs may form acute, obtuse, and/or right angles with the connectors in both deployed and undeployed configurations. In general, the prongs extend outwards at an angle from the planes defined by the connections of the proximal and distal anchors and the connecting member. Prongs may also be bent multiple times, as shown in the third and fourth rows of  FIG. 6 .  FIG. 6  is not exhaustive; other combinations of prong configurations are also possible. Proximal prongs typically span diameters of more than about 50 mm to prevent the anchors from being pulled into the intestine. For example, the diameter spanned by the proximal prongs may be about 50 mm or more, and is preferably about 60 mm or more. Similarly, distal prongs usually span diameters of about 40 mm or more to prevent the anchors from being pulled into the stomach. Connector diameters range from about 10 mm to about 25 mm, depending on the location of the seal. Transpyloric anchors with seals on either side of the pylorus may have connectors with smaller diameters. Connectors with larger diameters may press up against the pylorus to tightly close gaps between the anchor and the pylorus. 
         [0034]    Transpyloric anchors may be inserted endoscopically in a variety of undeployed configurations. Once inserted, a transpyloric anchor may self-expand across the pylorus, as shown in  FIGS. 1 and 2 , to secure a sleeve within the duodenum. For example, a gastrointestinal implant device that includes a transpyloric anchor and a sleeve can be inserted into the gastrointestinal tract with the devices and methods disclosed in U.S. Pat. No. 7,678,068 and U.S. Pat. No. 7,122,058, both of which are incorporated herein by reference in their entireties. The deployed transpyloric anchor and attached sleeve can be removed endoscopically by simply pulling the anchor towards the patient&#39;s mouth. To minimize trauma during retrieval, the transpyloric anchor can be pulled out with a hooded retrieval device: first, the retrieval device is used to grasp a drawstring that runs through the transpyloric anchor. Pulling the drawstring collapses the transpyloric anchor. The hood shields the gastrointestinal tract from the collapsed transpyloric anchor as the anchor is withdrawn, as described in U.S. patent application Ser. No. 12/005,049, filed Dec. 20, 2007, and incorporated herein by reference in its entirety. 
         [0035]      FIGS. 7A and 7B  show elevation and plan views, respectively, of an alternative implant  700  that includes a transplyoric anchor  710  covered in fluoropolymer. The transplyoric anchor  710  is used to secure a restrictor plate  720  within the gastrointestinal tract to treat obesity, as disclosed in U.S. patent application Ser. No. 10/811,293, U.S. patent application Ser. No. 11/330,705, and U.S. patent application Ser. No. 11/827,674, all of which are incorporated herein by reference in their entireties. The restrictor plate  720  has a restricting aperture  722  at its center that retards the outflow of food from the stomach to the intestine. The diameter of the aperture  722  is less than about 10 millimeters, and is preferably in the range of about 3-7 millimeters. The aperture  722  may be elastic and expandable under pressure from material flowing through the anchor and the aperture at elevated physiological pressures; as pressure increases, the apertures opens to greater diameters. The restrictor plate  720  and/or the anchor  710  may also be coupled to a sleeve (not shown) that extends into the intestine. 
         [0036]    While this invention has been particularly shown and described with references to example 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.