Abstract:
An inexpensive small-sized screen printing machine having low redundancy and high production efficiency and applicable to a dual conveying-type component mounting machine. A pair of substrate supporting tables juxtaposed in a specific direction is provided. Screen printing is alternately performed by a single print executing section in a common area which can be shared by the two substrate supporting tables. In doing so, when one substrate supporting table located at a print position among the pair of substrate supporting tables starts exiting the print position, the other substrate supporting table starts entry to the print position.

Description:
INTRODUCTION 
       [0001]    The invention relates to a device. In one aspect the invention relates to a gastrointestinal implant device. 
         [0002]    There are several procedures and devices for treatment of obesity. Whilst many of these devices are successful in the short term various problems can arise because the patient does not achieve a feeling of satiety (fullness) after eating. 
       STATEMENTS OF INVENTION 
       [0003]    According to the invention there is provided a luminal prosthesis comprising:
       a first part which is adapted to be retained in a lumen; and   a second part which is connected to the first part such that a force applied to the second part is at least partially isolated from the first part.       
 
         [0006]    The second part may be adapted for mounting of a device such as a valve. 
         [0007]    The prosthesis may comprise a connector between the first part and the second part. The connector may comprise at least one tether. The connector may comprise at least one strut. The connector may comprise at least one wire. 
         [0008]    In one case the first part and the second part are formed from a single precursor. 
         [0009]    The precursor may comprise one continuous stent which is folded to form the first part and the second part. 
         [0010]    In one case the second part is radially inward of the first part. 
         [0011]    The first part may comprise a bulbous region. 
         [0012]    The second part may comprise a scaffold-receiving region. 
         [0013]    The prosthesis may comprise a proximal flare. There may be a transition region between the bulbous region and the proximal flare. 
         [0014]    In one case the prosthesis comprises a bulbous region, a proximal flare and a scaffold receiving region. 
         [0015]    The proximal flare may be of open mesh construction. The proximal flare may be adapted to resist axial movement of the prosthesis. The proximal flare may be at least partially coated. In one case the proximal flare has a peripheral region which is coated. 
         [0016]    In one embodiment the bulbous region is partially coated. 
         [0017]    In one case the scaffold receiving region is stiff relative to the bulbous region. 
         [0018]    The prosthesis may comprise a transition region between the proximal flare and the bulbous region. The transition region may be of open mesh soft construction. 
         [0019]    The prosthesis may be of braided mesh construction. 
         [0020]    In one aspect the invention provides a luminal prosthesis comprising an outer region and an inner region connected to the outer region, the inner region being adapted for mounting of a device such as a valve. The inner region may be connected to the outer region by a connecting means such as struts and/or wires. The inner region may be formed by an extension of the outer region. The inner region and the outer region are formed by one continuous stent folded to form inner and outer regions. In one case the luminal prosthesis comprises a proximal flare, a bulbous region, and a scaffold receiving region. 
         [0021]    In one embodiment the prosthesis has a reinforcement to facilitate radial compression during loading and to limit radial expansion. The reinforcement may extend around at least part of the circumference of the stent. The reinforcement may comprise at least one loop. 
         [0022]    In one case the reinforcement is non-distensible. The reinforcement may be of flexible material. In one case the reinforcement is of a polymeric or metallic thread. The reinforcement may be a material selected from one or more of the group comprising monofilament or braided polypropylene suture or a stainless steel wire. 
         [0023]    The invention also provides luminal self expanding prosthesis having a reinforcement to facilitate radial compression during loading and to limit radial expression. In one case the reinforcement extends around at least part of the circumference of the stent. The reinforcement may comprise at least one loop. The reinforcement may be non-distensible. The reinforcement may be of a flexible material. The reinforcement may be of a polymeric or metallic thread. The reinforcement may be of a material selected from one or more of the group comprising monofilament or braided polypropylene suture or a stainless steel wire. 
         [0024]    The invention also provides a gastrointestinal implant device comprising a prosthesis of the invention. 
         [0025]    Also provided is a gastrointestinal implant device comprising:
       a sleeve for extending into the duodenum;   an artificial valve for placement at the pylorus to control flow from the stomach into the duodenal sleeve; and   a support structure for the valve, the support structure comprising a scaffold to which the valve is mounted and a luminal prosthesis of the invention.       
 
         [0029]    According to the invention there is provided a luminal prosthesis comprising an outer region and an inner region connected to the outer region, the inner region being adapted for mounting of a device such as a valve. 
         [0030]    In one embodiment the inner region is connected to the outer region by a connecting means such as struts and/or wires. 
         [0031]    In another embodiment the inner region is formed by an extension of the outer region. The inner region and the outer region may be formed by one continuous stent folded to form inner and outer regions. 
         [0032]    In one case the luminal prosthesis comprises a proximal flare, a bulbous region, and a scaffold receiving region 
         [0033]    The invention also provides a gastrointestinal implant device comprising a prosthesis of the invention. 
         [0034]    The invention provides a gastrointestinal implant device comprising:
       a sleeve for extending into the duodenum;   an artificial valve for placement at the pylorus to control flow from the stomach into the duodenal sleeve; and   a support structure for the valve, the support structure comprising a scaffold to which the valve is mounted and a luminal prosthesis of the invention.       
 
         [0038]    According to the invention there is provided a gastrointestinal implant device comprising:
       a sleeve for extending into the duodenum; and   an artificial valve for placement at the pylorus to control flow from the stomach into the duodenal sleeve; and   a support structure for the valve.       
 
         [0042]    The invention also provides a gastrointestinal implant device comprising:
       a sleeve for extending into the duodenum;   an artificial valve for placement at the pylorus to control flow from the stomach into the duodenal sleeve; and   a support structure for the valve, the support structure comprising a scaffold to which the valve is mounted and a luminal prosthesis, the luminal prosthesis comprising a proximal flare, a bulbous region, and a scaffold receiving region.       
 
         [0046]    In one embodiment the scaffold receiving region is located intermediate the proximal end and the distal end of the luminal prosthesis. 
         [0047]    The scaffold receiving region may be located between the proximal flare and the bulbous region. 
         [0048]    In one embodiment the valve is configured to open only when a pre-set back pressure on the valve has been overcome. 
         [0049]    In one embodiment the support structure comprises a scaffold to which the valve is mounted. The support structure may comprise a luminal prosthesis. 
         [0050]    In one case the support structure comprises a scaffold to which the valve is mounted and a luminal prosthesis. The scaffold may be releasably mountable to the luminal prosthesis. 
         [0051]    In one embodiment the sleeve is mounted to the support structure. In one case The sleeve is releasably mountable to the support structure. In one case the support structure comprises a scaffold and the sleeve is mounted to the scaffold. 
         [0052]    In one embodiment the support structure comprises a stent-like structure. 
         [0053]    In one case the support structure comprises a stent-like scaffold. 
         [0054]    In one embodiment the support structure comprises a luminal prosthesis for deployment at the pylorus and a scaffold to which the valve is mounted, the scaffold being releasably mountable to the pre-deployed luminal prosthesis. The scaffold may be releasably engagable with the luminal prosthesis. The scaffold may comprise engagement elements which are releasably engagable with the luminal prosthesis. In one case the engagement elements comprise protrusions which are releasably engagable with the luminal prosthesis. 
         [0055]    In one embodiment the luminal prosthesis comprises a mesh. The mesh may be coated with a coating. The protrusions may engage with the mesh. The protrusions may penetrate the mesh. 
         [0056]    In one embodiment the device comprises a release means for releasing the scaffold from engagement with a pre-deployed luminal prosthesis. The release means may comprise means for reducing the diameter of at least a portion of the scaffold. The release means may comprise a drawstring extending around the scaffold. 
         [0057]    There may be a first drawstring extends around a proximal end of the support structure. There may be a second drawstring extends around a distal end of the support structure. 
         [0058]    In one embodiment the valve is mounted to the support structure. The valve may be sutured to the support structure. The valve may be bonded to the support structure. The valve may be adhesively bonded to the support structure. 
         [0059]    In one case a proximal end of the sleeve is mounted to the support structure. The sleeve may be sutured to the support structure. The sleeve may be bonded to the support structure. The sleeve may be adhesively bonded to the support structure. 
         [0060]    In one embodiment the support structure comprises a scaffold which is of substantially uniform diameter. 
         [0061]    In one case the support structure comprises a luminal prosthesis. 
         [0062]    The luminal prosthesis may comprise a proximal flare. The luminal prosthesis may comprise a distal bulbous region. The luminal prosthesis may comprise a scaffold receiving region. The scaffold receiving region may be intermediate the proximal and distal ends of the luminal prosthesis. 
         [0063]    In one embodiment the sleeve is of substantially uniform diameter along the length thereof. 
         [0064]    In another embodiment the sleeve has a first diameter at a proximal end and a second diameter at the distal end which is larger than the first diameter. The sleeve may be tapered. 
         [0065]    In one embodiment the sleeve comprises a retaining means to assist in retaining the sleeve at a desired location. The retaining means may comprise a retaining ring. A retaining ring may be located at or adjacent to a distal end of the sleeve. 
         [0066]    There may be a plurality of retaining rings which are axially spaced-apart along the sleeve. 
         [0067]    In one case the retaining ring comprises a biasing means. The biasing means may comprise a flexible material which is biased into an expanded configuration. 
         [0068]    In one embodiment the retaining ring is oversized with respect to the sleeve. 
         [0069]    The device may comprise release means for releasing the retaining ring from engagement. The release means may comprise a drawstring. 
         [0070]    In one embodiment the sleeve has a retracted delivery configuration and an expanded deployed configuration. The sleeve may be folded in the retracted delivery configuration. 
         [0071]    In one embodiment the valve has a normally closed configuration and an open configuration in which the valve is opened for stomach emptying. 
         [0072]    In one case the valve is adapted to open automatically for stomach emptying and to return automatically to the closed configuration. 
         [0073]    The valve may be of a viscoelastic polymeric foam which may be biomimetic. 
         [0074]    In one embodiment the valve comprises an outer support region, at least three valve leaflets, and a main body region extending between the support region and the valve leaflets. The valve may have a region of co-aption of the valve leaflets in the closed configuration. The region of co-aption may extend for an axial length of at least 1 mm. 
         [0075]    In one embodiment the device is adapted for placement in the pyloric sphincter or valve. 
         [0076]    In another embodiment the device is adapted for placement distal of the pyloric sphincter. 
         [0077]    In one embodiment the support is adapted for mounting to a pre-deployed sleeve which extends into the duodenum. 
         [0078]    The invention also provides a delivery system for a gastrointestinal implant device, the implant device comprising an artificial valve, a duodenal sleeve and a support structure for the valve and the sleeve, the device having a retracted delivery configuration and an expanded deployed configuration, the delivery system comprising a delivery catheter having a distal pod for the implant device in the retracted configuration; and a sleeve deployment system. 
         [0079]    In one case the sleeve deployment system comprises:
       a distal cap;   a fluid delivery lumen for extending through the sleeve;   a distal seal between the distal cap and the lumen; and   a proximal seal,
 
whereby delivery of fluid through the lumen and into the sleeve causes the sleeve to expand from an axially retracted delivery configuration to an axially expanded deployed configuration.
       
 
         [0084]    The proximal seal may be sealingly engagable with the pod for deployment of the sleeve. 
         [0085]    The proximal seal may be sealingly engagable with the valve for deployment of the sleeve. 
         [0086]    In one case the pod is detachable from the delivery catheter. 
         [0087]    The proximal seal may comprise an inflatable balloon. 
         [0088]    The distal seal may comprise an inflatable balloon. The delivery system may include a flexible tube for inflating the distal balloon. 
         [0089]    The delivery system in one embodiment comprises a deployer for deploying the support structure and the valve to which the support structure is mounted. In one case the deployer comprises an abutment. The abutment may be provided by a balloon. The deployer balloon may comprise the proximal balloon. 
         [0090]    In one embodiment the distal cap or olive is releasably mounted to the fluid delivery lumen. 
         [0091]    The invention also provides a gastrointestinal implant comprising a sleeve for extending into the duodenum, the sleeve having a pocket containing a radiopaque marker. The pocket may extend at least partially along the length of the sleeve. 
         [0092]    In one embodiment the sleeve has a plurality of pockets for reception of a radiopaque marker. 
         [0093]    The radiopaque marker may comprise a fluid or gel. The fluid may comprise a silicon resin filled with a radiopaque material such as barium sulphate. 
         [0094]    The invention also provides a method for treating obesity and/or diabetes comprising the steps of:
       providing a luminal prosthesis;   providing a valve mounted to a support scaffold, the valve having a retracted delivery configuration and an expanded deployed configuration;   providing a liner sleeve for lining the duodenum;   delivering the luminal prosthesis to a location at or distal of the pylorus;   deploying the luminal prosthesis at the location in the pylorus;   delivering the valve and support scaffold to the location; and   deploying the sleeve so that the sleeve extends from the valve and into the duodenum.       
 
         [0102]    In one embodiment the method comprises deploying the valve and support structure so that the support structure engages with the predeployed luminal prosthesis. 
         [0103]    In one embodiment the luminal prosthesis is deployed in the pyloric sphincter. 
         [0104]    In another embodiment the luminal prosthesis is deployed distal of the pyloric sphincter. 
         [0105]    The method may comprise releasing the valve support structure from engagement with the luminal prosthesis; and withdrawing the valve support structure, the valve, and the sleeve from the location. The method may comprise repeating the appropriate steps to deploy a valve, a support structure for the valve, and a sleeve at the desired location. 
         [0106]    The invention further provides a method for treating obesity and/or diabetes comprising the steps of:
       providing a valve mounted to a support structure;   delivering the valve mounted to the support structure to a pre-deployed sleeve which extends into the duodenum; and   deploying the valve so that the valve is mounted to the sleeve.       
 
         [0110]    The step of deploying the valve may comprise engaging the valve support with the pre-deployed luminal prosthesis. 
         [0111]    In one case the valve support is an expandable support and the method comprises loading the support onto a delivery catheter in a retracted form and the valve support is expandable on deployment. The support may be self expandable. The support may be expanded by an expanding means such as a balloon. 
         [0112]    In one case the method comprises the step of releasing the valve support from engagement with the luminal prosthesis. The method may comprise repositioning the valve support within the sleeve. The valve may be removed from the sleeve. 
         [0113]    The invention also provides a gastrointestinal implant device comprising a pyloric valve for placement at the pylorus to control flow from the stomach into the duodenum,
       the valve being of a viscoelastic foam and comprising at least three valve leaflets,   the valve having a normally closed configuration and an open configuration,   the valve leaflets being movable from the closed configuration to the open configuration for flow from the stomach.       
 
         [0117]    In one embodiment the valve is adapted to open automatically for stomach emptying and to return automatically to the closed configuration. The valve may comprise an outer support region and a main body region extending between the support region and the valve leaflets. The valve may have a region of co-aption of the valve leaflets in the closed configuration. 
         [0118]    In one case the device comprises an anchor for anchoring the valve at the pylorus. 
         [0119]    In one case the anchor comprises a support structure for the valve. The anchor may comprise a support scaffold for the valve and a luminal prosthesis to which the scaffold is mountable. 
         [0120]    In one case the device comprises a sleeve for extending into the duodenum. The sleeve may be mounted to the valve or to an anchor for the valve. The device may be adapted for placement in the pyloric sphincter or may be adapted for placement distal of the pyloric sphincter. 
         [0121]    According to the invention there is provided a gastrointestinal implant device comprising a valve for placement at the pylorus to control the rate of stomach emptying. 
         [0122]    In one embodiment the valve has a normally closed configuration and an open configuration in which the valve is opened for stomach emptying. 
         [0123]    There may be a support for the valve. The support may be adapted for mounting to a pre-deployed sleeve which extends into the duodenum. 
         [0124]    In one embodiment the implant device is adapted for placement in the pyloric valve. 
         [0125]    In a further embodiment the implant device is adapted for placement distal of the pyloric valve. 
         [0126]    The valve support may comprise a support structure. The support structure may taper outwardly. The support structure may taper inwardly. 
         [0127]    In another case the support structure is of generally uniform diameter along the length hereof. 
         [0128]    The support structure may comprise a scaffold. 
         [0129]    The support structure may comprise a stent-like structure. 
         [0130]    In one case the device comprises mounting means for mounting the valve support to a pre-deployed luminal prosthesis. 
         [0131]    The mounting means may be releasably engagable with a pre-deployed host support. 
         [0132]    The device may comprise release means for releasing the valve from engagement with a pre-deployed host support. The release means may comprise means for reducing the diameter of at least portion of the valve support structure. The release means may comprise a drawstring extending around the valve support structure. There may be a first drawstring which extends around a proximal end of the support structure. There may be a second drawstring which extends around a distal end of the support structure. 
         [0133]    In one case the valve is mounted to the support structure. The valve may be sutured to the support structure. 
         [0134]    The valve may be bonded to the support structure. The valve may be adhesively bonded to the support structure. 
         [0135]    In one embodiment the valve is adapted to open automatically in the one direction. 
         [0136]    The invention also provides a method for treating obesity and/or diabetes comprising the steps of:
       providing a valve mounted to a support structure;   delivering the valve mounted to the support structure to a pre-deployed sleeve which extends into the duodenum; and   deploying the valve so that the valve is mounted to the sleeve.       
 
         [0140]    The step of deploying the valve may comprise engaging the valve support with the pre-deployed luminal prosthesis. 
         [0141]    In one case the valve support an expandable support and the method comprises loading the support onto a delivery catheter in a retracted form and the valve support is expandable on deployment. 
         [0142]    The support may be self expandable. Alternatively the support is expanded by an expanding means. The expanding means may comprise a balloon. 
         [0143]    In one embodiment the method comprises the step of releasing the valve support from engagement with the luminal prosthesis. The method may comprise repositioning the valve support within the sleeve. 
         [0144]    In one case the method comprises removing the valve from the sleeve. 
         [0145]    In one embodiment the valve comprises a polymeric valve body having an outer support rim, at least three valve leaflets, and a main body region extending between the support rim and the valve leaflets. 
         [0146]    The invention also provides a valve comprising at least four valve leaflets, the valve having a normally closed configuration in which the leaflets are engaged and an open configuration in which the leaflets are open. There may be at least five valve leaflets. There may be six valve leaflets. 
         [0147]    The valve may comprise a valve body of polymeric material. The valve may comprise an outer support region. The valve may also have a main body region extending between the support region and the valve leaflets. 
         [0148]    In one case the main body region is generally concave between the outer support rim and a region of co-aption of the valve leaflets. 
         [0149]    In one case the valve leaflets have a region of co-aption and the valve body is reinforced at the region of co-aption. The valve body may be thickened at the region of co-aption. 
         [0150]    The region of co-aption may extend for an axial length of at least 1 mm. The region of co-aption may extend for a depth of from 1 mm to 5 mm. 
         [0151]    In one embodiment the support rim of the valve body is reinforced. The support rim of the valve may be thickened. 
         [0152]    In one embodiment the valve comprises three valve leaflets. 
         [0153]    In another embodiment the valve comprises six valve leaflets. 
         [0154]    The valve may be mounted to the support structure. 
         [0155]    In one case the valve rim is sutured to the support structure. Alternatively or additionally the valve rim is bonded to the support structure. 
         [0156]    In one embodiment the support structure comprises a luminal prosthesis. 
         [0157]    In one case the luminal prosthesis extends proximally of the valve. 
         [0158]    In another case the luminal prosthesis extends distally of the valve. 
         [0159]    In one embodiment the luminal prosthesis extends proximally and distally of the valve. 
         [0160]    The luminal prosthesis may have a coating and/or a sleeve thereon. The coating or sleeve may be on the outside of the luminal prosthesis. Alternatively the coating or sleeve is on the inside of the luminal prosthesis. 
         [0161]    In one embodiment the polymeric material is stable to gastric fluid for at least 3 months, for at least 4 months, for at least 5 months, for at least 6 months, for at least 7 months, for at least 8 months, for at least 9 months, for at least 10 months, for at least 11 months, or for at least one year. 
         [0162]    In one case the polymeric material takes up less than about 5%, less than about 10%, less than about 15%, less than about 20%, less than about 25%, or less than about 30% by weight of water at equilibrium. 
         [0163]    In one case the polymeric material of the valve body has a % elongation of from 50% to 3000% or 200% to 1200%. 
         [0164]    In one case the polymeric material of the valve body has a tensile strength of from 0.01 to 5 MPa or about 0.1 to 1.0 MPa, or about 0.25 to 0.5 MPa. 
         [0165]    In one embodiment the polymeric material has a Young&#39;s Modulus of about 0.01 to 0.6 MPa, or about 0.1 to about 0.5 MPa. 
         [0166]    In one embodiment the polymeric material of the valve body has a density of from 0.1 g/cm 3  to 1.5 g/cm 3 , or 0.3 to 1.2 g/cm 3 , or 0.8 to 0.9 g/cm 3 , or 0.5 to 0.6 g/cm 3 . 
         [0167]    In one embodiment the distance between the proximal end of the support region of the valve body and the distal end of the valve leaflets is less than 50 mm, or less than 40 mm, or less than 30 mm, or less than 25 mm, or less than 20 mm, or less than 15 mm. 
         [0168]    In one case the polymeric material of the valve body is of an elastic material. 
         [0169]    In another case the polymeric material of the valve body is of a viscoelastic material. 
         [0170]    In one embodiment the polymeric material of the valve body comprises a foam. The polymeric material of the valve body may comprise an open cell foam. 
         [0171]    In one embodiment the polymeric material of the valve body comprises a polyurethane foam. 
         [0172]    In one embodiment the valve is adapted to be mounted to a pre-deployed support structure, for example an esophageal luminal prosthesis such as a stent. 
         [0173]    The invention also provides a valve having:
       a normally closed configuration in which the valve is closed;   an open configuration in which the valve is opened for flow through the valve; and   a support for the valve, the support being adapted for mounting to a pre-deployed luminal prosthesis intermediate a proximal end and a distal end of the predeployed luminal prosthesis.       
 
         [0177]    In one case the luminal prosthesis has a coating and/or sleeve thereon. The coating or sleeve may be on the outside of the luminal prosthesis. Alternatively or additionally the coating or sleeve is on the inside of the luminal prosthesis. 
         [0178]    The mounting means may be provided by the support structure. In one case the mounting means comprises protrusions extending from the support structure. The protrusions may be adapted to engage with a pre-deployed host esophageal luminal prosthesis. 
         [0179]    In one embodiment the protrusion comprises a loop. 
         [0180]    In one case the apicial tip of the protrusion is rounded. 
         [0181]    There may be release means for releasing the valve from engagement with a pre-deployed host luminal prosthesis. The release means may comprise means for reducing the diameter of at least portion of the valve support structure. 
         [0182]    In one case the release means comprises a drawstring extending around the valve support structure. A first drawstring may extend around a proximal end of the support structure. A second drawstring may extend around a distal end of the support structure. 
         [0183]    In one embodiment the valve is mounted to the support structure. The valve may be sutured to the support structure. The valve may be bonded to the support structure. The valve may be adhesively bonded to the support structure. 
         [0184]    In another case the mounting means comprises a surgical adhesive. 
         [0185]    The invention also provides a method for providing a valve in a body passageway comprising the steps of:
       providing a valve mounted to a support structure;   delivering the valve mounted to the support structure to a pre-deployed luminal prosthesis in the body passageway; and   deploying the valve so that the valve is mounted to the luminal prosthesis.       
 
         [0189]    In one embodiment the step of deploying the valve comprises engaging the valve support with the pre-deployed luminal prosthesis. 
         [0190]    The valve support may be mechanically engaged with the pre-deployed luminal prosthesis. 
         [0191]    In one case the valve support comprises a protrusion and the method comprises aligning the protrusion with an aperture in the endoluminal prosthesis and engaging the protrusion in the aperture. 
         [0192]    In one embodiment the valve support is an expandable support and the method comprises loading the support onto a delivery catheter in a retracted form and the valve support is extendable on deployment. 
         [0193]    The support may be self expandable or the support is expanded by an expanding means such as a balloon. 
         [0194]    In one embodiment the method comprises the step of releasing the valve support from engagement with the luminal prosthesis. 
         [0195]    The method may involve repositioning the valve support within the prosthesis. The method may comprise removing the valve from the prosthesis. 
         [0196]    In one embodiment the luminal prosthesis extends proximally of the valve. The prosthesis may comprise a self expanding plastics mesh. The prosthesis may apply a radial force of less than 1.9 kPa. 
         [0197]    In one embodiment there are anchors for mounting the prosthesis in situ. The anchors may be adapted to extend through the mesh of the prosthesis. 
         [0198]    In one embodiment the length of the valve from the proximal end of the support region to the distal end of the valve leaflets is less than 50 mm, less than 40 mm, less than 30 mm. The length of the valve may be approximately the same as the outer diameter of the support region of the valve. The length of the valve may be approximately 23 mm. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0199]    The invention will be more clearly understood from the following description thereof given by way of example only, in which: 
           [0200]      FIG. 1  is an isometric view (from above) of a valve according to the invention; 
           [0201]      FIG. 2  is an isometric view (from below) of the valve; 
           [0202]      FIG. 3  is a top plan view of the valve; 
           [0203]      FIG. 4  is an underneath plan view of the valve; 
           [0204]      FIGS. 5 and 6  are elevational views of the valve; 
           [0205]      FIGS. 7 and 8  are isometric, partially cut-away sectional, views of the valve; 
           [0206]      FIGS. 9 and 10  are cross sectional views of the valve; 
           [0207]      FIG. 11  is a cross sectional view of the valve in a normally closed configuration; 
           [0208]      FIG. 12  is a cross sectional view of the valve in an open configuration in response to a force; 
           [0209]      FIG. 13  is a cross sectional view of the valve returned to the closed configuration after opening to flow; 
           [0210]      FIG. 14  is an isometric view (from above) of the valve in a normally closed configuration; 
           [0211]      FIG. 15  is an isometric view of the valve in a partially open configuration in response to a force; 
           [0212]      FIG. 16  is an isometric view of the valve in a fully open configuration in response to a force; 
           [0213]      FIG. 17  is an isometric view of a prosthesis; 
           [0214]      FIG. 18  is an elevational view of the valve of  FIGS. 1 to 16  being mounted to and in position on the prosthesis of  FIG. 17 ; 
           [0215]      FIG. 19  is another view of the valve mounted in a prosthesis; 
           [0216]      FIGS. 20 and 21  are isometric views of a sleeved or coated prosthesis; 
           [0217]      FIG. 22  is an isometric view of the prosthesis of  FIGS. 20 and 21  with a valve of  FIGS. 1 to 16  in position; 
           [0218]      FIG. 23  is an elevational view of part of the prosthesis of  FIG. 22  in position; 
           [0219]      FIG. 24  is an isometric view of a valve according to another embodiment of the invention; 
           [0220]      FIG. 25  is an elevational view of the valve of  FIG. 24 ; 
           [0221]      FIG. 26  is an isometric view of another valve according to the invention with a distally outward tapering support structure; 
           [0222]      FIG. 27  is an elevational view of the valve of  FIG. 26 . 
           [0223]      FIG. 28  is an isometric view of another valve according to the invention with a distally inward tapering support structure; 
           [0224]      FIG. 29  is an elevational view of a luminal prosthesis with a valve and associated support structure in place; 
           [0225]      FIG. 30  is an enlarged view of the luminal prosthesis and valve support structure of  FIG. 29 ; 
           [0226]      FIGS. 31 and 32  are enlarged views of one mounting detail of a valve support structure to a luminal prosthesis; 
           [0227]      FIGS. 33 to 37  are views of a valve being deployed from a delivery catheter; 
           [0228]      FIGS. 38 to 40  are views of a luminal prosthesis in situ with a valve being deployed in the lumen of the luminal prosthesis. 
           [0229]      FIG. 41  is an elevational view of a valve according to another embodiment of the invention; 
           [0230]      FIG. 42  is an enlarged view of a detail of the support structure of the valve of  FIG. 41 ; 
           [0231]      FIGS. 43 and 44  are isometric views of the valve of  FIGS. 41 and 42  being deployed from a delivery catheter; 
           [0232]      FIG. 45  is an elevational view of a prosthesis with the valve of  FIGS. 43 and 44  in situ; 
           [0233]      FIG. 46  is an enlarged view of a detail of the engagement of the valve support structure of 
           [0234]      FIGS. 41 to 45  engaged in the mesh of the prosthesis; 
           [0235]      FIG. 47  is an enlarged view of part of the luminal prosthesis and valve support structure of  FIG. 46 ; 
           [0236]      FIG. 48  is an elevational view of a luminal prosthesis; 
           [0237]      FIG. 49  is an elevational of an esophageal valve of the invention; 
           [0238]      FIGS. 50 to 55  are elevational views of steps involved in deploying the valve of  FIG. 49  into a pre-deployed luminal prosthesis of  FIG. 48 ; 
           [0239]      FIG. 56  is an elevational view of the valve of  FIG. 49  deployed in the luminal prosthesis of  FIG. 55 ; 
           [0240]      FIG. 57  is an elevational view similar to  FIG. 56  with the valve being removed from the deployed prosthesis; 
           [0241]      FIG. 58  is an isometric view of a valve according to the invention; 
           [0242]      FIG. 59  is an elevational view of the valve of  FIG. 56 ; 
           [0243]      FIG. 60  is a plan view of the valve of  FIGS. 58 and 59  with the valve in a closed configuration; 
           [0244]      FIG. 61  is a plan view similar to  FIG. 60  with the valve in an open configuration; 
           [0245]      FIGS. 62 and 63  are side views of the device of  FIG. 60  with the valve in a closed configuration; 
           [0246]      FIGS. 64 and 65  are side views of the device of  FIG. 60  with the valve in the open configuration; 
           [0247]      FIG. 66  is an illustration of a gastrointestinal implant device according to one embodiment of the invention; 
           [0248]      FIG. 67  is an enlarged view of detail A of  FIG. 66 ; 
           [0249]      FIGS. 68 and 69  are illustrations of another gastrointestinal implant device located in the pyloric sphincter; 
           [0250]      FIGS. 70 and 71  are illustrations similar to  FIGS. 66 and 67  with the device located distal of the pyloric sphincter; 
           [0251]      FIG. 72  is an isometric view of a luminal prosthesis of an implant device of the invention; 
           [0252]      FIG. 73  is an elevational view of a valve, sleeve and scaffold part of an implant device; 
           [0253]      FIG. 74  is an elevational, partially cross sectional view of an implant device with a prosthesis located in a lumen such as the pylorus and a valve, sleeve and scaffold for mounting to the prosthesis; 
           [0254]      FIG. 75  is an elevational view of the device of  FIG. 72  assembled; 
           [0255]      FIG. 76  is an elevational view of the device of  FIG. 75  with the sleeve extended; 
           [0256]      FIG. 77  is an elevational, partially cross sectional view of the device, in situ; 
           [0257]      FIG. 78  is a view similar to  FIG. 77  of an implant device with a sleeve in one folded delivery configuration; 
           [0258]      FIG. 79  is a view similar to  FIG. 78  with the sleeve in another folded delivery configuration; 
           [0259]      FIG. 80  is a view similar to  FIG. 79  with the sleeve in a further folded delivery configuration; 
           [0260]      FIG. 81  is an elevational, partially cross sectional view of an implant device including a retaining ring for a sleeve; 
           [0261]      FIG. 82  is a view similar to  FIG. 81  of another sleeve; 
           [0262]      FIG. 83  is a view similar to  FIG. 81  with a sleeve having a plurality of retaining rings; 
           [0263]      FIG. 84  is cross sectional view illustrating a first stage in the delivery of an implant device to the pylorus; 
           [0264]      FIG. 85  is a cross sectional view of the implant device in position with the sleeve in a retracted configuration; 
           [0265]      FIG. 86  is a cross sectional view of the implant device in situ, with the sleeve partially extended; 
           [0266]      FIG. 87  is a cross sectional view similar to  FIG. 86  with the sleeve further extended; 
           [0267]      FIG. 88  is an enlarged cross sectional view of a distal end of the delivery system; 
           [0268]      FIG. 89  is a cross sectional view of the implant device in situ with the sleeve extended and the delivery system being removed; 
           [0269]      FIG. 90  is an elevational view of a delivery catheter for the implant device; 
           [0270]      FIG. 91  is a cross sectional view of the delivery catheter of  FIG. 90  with a capsule containing the implant device; 
           [0271]      FIGS. 92 to 94  are views showing the delivery system at various stages; 
           [0272]      FIG. 95  is a cross sectional view of a proximal end of the delivery system capsule; 
           [0273]      FIG. 96  is an elevational view of part of the delivery system; 
           [0274]      FIG. 97  is an exploded view of part of delivery system of  FIG. 96 ; 
           [0275]      FIG. 98  is a graph of pressure profile over time with various fixed orifice restrictors; 
           [0276]      FIG. 99  is a graph of pressure profile over time with a fixed orifice restriction and an implant device comprising a valve of the invention; 
           [0277]      FIG. 100  is a graph of pressure profile over time with a fixed orifice restriction and implant devices comprising valves of the invention; 
           [0278]      FIG. 101  is an isometric view of part of a sleeve according to the invention; 
           [0279]      FIG. 102  is a cross sectional view of the sleeve of  FIG. 93 ; 
           [0280]      FIG. 103  is an isometric view of part of another sleeve according to the invention; 
           [0281]      FIG. 104  is an isometric view of a luminal prosthesis according to the invention; 
           [0282]      FIG. 105  is an isometric view of another luminal prosthesis according to the invention 
           [0283]      FIGS. 106 and 107  are views of a luminal prosthesis in which inner and outer regions are connected by struts or vines; 
           [0284]      FIGS. 108 and 109  are views of a continuous stent which has been folded or partially inverted to generate two coaxial regions; 
           [0285]      FIG. 110  is an illustration of the longitudinal shortening of a stent resulting in migration of a valve device; 
           [0286]      FIG. 111  are views of a stent with restricting loops for restricting expansion of a section of a self expanding stent; 
           [0287]      FIGS. 112 and 113  are views of stents with restricting loops; 
           [0288]      FIG. 114  is an isometric view of another luminal prosthesis according to the invention; 
           [0289]      FIG. 115  is a view of the prosthesis of  FIG. 114  with a valve and scaffold in position; 
           [0290]      FIG. 116  is a plan view showing the valve in a closed configuration; 
           [0291]      FIG. 117  is an isometric view of an obesity treatment device in situ incorporating the device of  FIGS. 114 to 116 ; 
           [0292]      FIG. 118  is an isometric view of a precursor to another luminal prosthesis according to the invention; 
           [0293]      FIG. 119  is a view of the precursor of  FIG. 118  being folded; 
           [0294]      FIG. 120  is a view of a luminal prosthesis formed from the precursor of  FIG. 118 ; 
           [0295]      FIG. 121  is a view of the luminal prosthesis of  FIG. 120  with a valve and scaffold in situ; 
           [0296]      FIG. 122  is an isometric view of an obesity treatment device in situ incorporating the device of  FIGS. 120 and 121 ; 
           [0297]      FIG. 123  an isometric view of a further luminal prosthesis according to the invention; 
           [0298]      FIGS. 124 and 125  are diagrams illustrating different configurations of the prosthesis of  FIG. 123 ; 
           [0299]      FIG. 126  is an isometric view of a still further luminal prosthesis according to the invention; 
           [0300]      FIGS. 127 to 129  are diagrams illustrating different configurations of the prosthesis of  FIG. 126 ; 
           [0301]      FIG. 130  is an isometric view of a further luminal prosthesis according to the invention; 
           [0302]      FIG. 131  is an isometric view of another luminal prosthesis according to the invention; 
           [0303]      FIG. 132  is an isometric view of a still further luminal prosthesis of the invention; 
           [0304]      FIG. 133  is a side, partially cross sectional view of an obesity treatment device according to the invention; 
           [0305]      FIG. 134  is an isometric view of a valve, internal support and sleeve of the device of  FIG. 33 ; 
           [0306]      FIG. 135  is an isometric view of an external support of the device of  FIG. 133 ; 
           [0307]      FIG. 136  is an exploded view illustrating the mounting of the valve, internal support and sleeve of  FIG. 134  to the external support of  FIG. 135 ; 
           [0308]      FIG. 137  is a cross sectional view of the obesity treatment device of the invention, in use; 
           [0309]      FIG. 138  is am enlarged cross sectional view of the obesity treatment device in situ, in one configuration; and 
           [0310]      FIG. 139  is a view similar to  FIG. 140  with the device in another configuration of use. 
       
    
    
     DETAILED DESCRIPTION 
       [0311]    Referring to the drawings and initially to  FIGS. 1 to 16  thereof there is illustrated a valve  1  which can open automatically in one direction. 
         [0312]    The valve  1  comprises a polymeric valve body having a proximal outer support region with a rim  2 , at least three valve leaflets  3 ,  4 ,  5 , and a main body region  6  extending between the support rim  2  and the valve leaflets  3 ,  4 ,  5 . The valve leaflets  3 ,  4 ,  5  extend inwardly and distally and terminate at distal end faces  7 ,  8 ,  9  respectively. The leaflets each  3 ,  4 ,  5  have legs a, b which extend at an included angle of 120° to each other. The adjacent pairs of legs  3   a;    4   a;    4   b;    5   b;    5   a ;  3   b;  co-apt to close the gap between the valve leaflets when the valve is in the normally closed configuration. 
         [0313]    The valve  1  has two configurations. The first configuration is a normally closed configuration in which the valve leaflets  3 ,  4 ,  5  co-apt to close the valve. The second configuration is an open configuration in which the valve leaflets  3 ,  4 ,  5  are opened such that the leaflet leg pairs  3   a;    4   a ;  4   b;    5   b;    5   a;    3   b  are opened and spaced-apart in response to a force F 1  to allow flow through the valve. 
         [0314]    The various configurations of the valve  1  are illustrated in  FIGS. 11 to 16 . In the first or normally closed configuration ( FIGS. 11 ,  14 ) the valve leaflets  3 ,  4 ,  5  co-apt. When a force F 1  is applied to the valve leaflets  3 ,  4 ,  5  the leaflet legs pairs  3   a;    4   a;    4   b;    5   b;  and  5   a;    3   b  open to allow antegrade flow to pass ( FIGS. 12 ,  16 ).  FIG. 15  illustrates a partially open configuration in response to flow. When the force F 1  is removed the leaflets  3 ,  4 ,  5  return to the closed position under the inherent biasing of the polymeric material of the valve body ( FIG. 13 ). 
         [0315]    The valve leaflets  3 ,  4 ,  5  are reinforced in the region of co-aption. In this case, this is achieved by a local thickening of the polymeric material in this region. Similarly the support rim  2  is reinforced by a local thickening of the polymeric material. 
         [0316]    The region of co-aption of the valve leaflets  3 ,  4 ,  5  has an axial extent which is typically from 1 to 5 mm. This ensures positive co-aption of the leaflets across a significant interfacial area when the valve is in the normally closed configuration. The thickness of the leaflets at the region of co-aption is typically between 0.1 mm and 10 mm. 
         [0317]    The valve body has a generally concave outer face and a generally convex inner face. 
         [0318]    The valve  1  of the invention returns to its original working position after being fully opened. This is accomplished without damaging the working valve. 
         [0319]    When the valve is opened by stomach emptying the leaflets open. 
         [0320]    One important characteristic influencing the functioning of the valve is the leaflet legs that impinge on one another. By varying the geometry and length of the leaflets  3 ,  4 ,  5  the valve  1  can be made to open at different pressures. Opening is also dependant on the elasticity and density of the material the device is made from. Additionally, the overall diameter and the diameter to which the leaflets open influence the opening force. 
         [0321]    The valve may be of any suitable biocompatible polymeric material. It may be of a biocompatible polymeric material having properties which allow the valve to function as described. 
         [0322]    The materials used for the production of this valve have a % elongation between 50% and 3000%. The material also has a tensile strength of between 0.01 and 5 MPa. Additionally the material could have an antimicrobial action to prevent colonisation when in-vivo. Additionally the material can be elastic or viscoelastic and can optionally be an open cell foam. The density of the material should be between 0.1 g/cm3 to 1.5 g/cm3. 
         [0323]    The valve of the invention may be mounted to any suitable luminal prosthesis, especially a prosthesis or stent. The rim  2  of the valve provides a mounting ring for mounting within the stent  20 , for example, the valve  1  may be mounted to the stent by suturing the rim  2  to the stent mesh using sutures  21  as illustrated in  FIGS. 18 and 19 . 
         [0324]    The stent may be of any suitable type. An uncoated or unsleeved stent  20  is illustrated in  FIGS. 17 to 19 . Alternatively, if it is desired to prevent tissue ingrowth a stent  30  having a sleeve  31  may be used ( FIGS. 20 to 23 ). In this case the sleeve  31  is external of the stent. In other cases there may alternatively or additionally be an internal sleeve. Further, the stent may have a coating. 
         [0325]    A valve such as described above may also be placed into a pre-deployed luminal prosthesis. 
         [0326]    In one case a valve  100  may have a co-axial support structure or scaffold  102  is shown in  FIGS. 24 and 25 . The scaffold  102  is designed to engage with any suitable esophageal stent  140  as illustrated in  FIG. 29 . The mechanism of engagement can be by protrusions which may for example be proximal and/or distal apices  103  of the scaffold  102  which engage into the mesh of the existing pre-deployed stent  140 . Alternatively or additionally, the scaffold  102  may have features  150  designed to hook onto the inside of the struts of an esophageal stent as illustrated in  FIGS. 31 and 32 . 
         [0327]    Referring to  FIGS. 26 and 27  there is illustrated a valve  110  according to another embodiment of the invention in which the support structure or scaffold  102  tapers distally outwardly so that distal apices  111  of the scaffold engage with the mesh of the existing pre-deployed host stent  140 . 
         [0328]    Referring to  FIG. 28  there is illustrated another valve  120  according to the invention in which the support structure or scaffold  102  tapers distally inward so that proximal apices  121  of the scaffold  102  engage with the mesh of an existing pre-deployed stent  140 . 
         [0329]    The radial force of the scaffold  102  may exert enough friction to hold the valve in place without the necessity for protrusion. In another embodiment a surgical adhesive may be used to secure the retrofitted valve into place. 
         [0330]    Referring to  FIGS. 33 to 37  a valve  100  is loaded into a delivery system  130  for deployment. The outer diameter of the delivery system  130  is smaller than the inner diameter of a pre-deployed esophageal stent  140 . The delivery system  130  in this case comprises a delivery catheter having a distal pod  131  in which a valve is housed in a contracted configuration. The catheter has a tapered distal tip  132  to avoid snagging on a pre-deployed stent  140 . The pod  131  is axially movable relative to the tip  132  to release the valve from the pod  131 . 
         [0331]    The delivery system  130  is used to deliver the valve to a pre-deployed stent  140  as illustrated in  FIG. 38 . The stent  140  has a mesh and the scaffold of the valve is adapted to engage with the mesh of the pre-deployed stent  140  on release of the valve from the delivery catheter as illustrated particularly in  FIGS. 39 and 40 . 
         [0332]    Referring to  FIGS. 29 to 32  there is illustrated an idealised stent  140  with a valve support scaffold  102  in situ. Details of a valve are omitted from these drawings for clarity. In this case the scaffold  102  is located at the upper proximal end of the stent. In this case the scaffold  102  has hook-like members  150  for engagement with the mesh of the stent  140  as illustrated in  FIGS. 31 and 32 . The interengagement between the stent  140  and the scaffold  102  ensures that the scaffold  102  and hence the valve which is fixed to it is retained in position and provides an anti-proximal migration mechanism. 
         [0333]    In the cases illustrated the valve supporting scaffold  102  is of a self expanding material such as a shape memory material, for example Nitinol. The valve and scaffold are loaded into the delivery catheter pod  131  in a compressed/reduced diameter configuration. When the constraint of the pod  131  is removed at the deployment site, the scaffold and valve self expand to the normal configuration in which the scaffold is engaged with the pre-deployed host stent  140 . In some arrangements the scaffold may be of an expensile material which is expanded by an expander such as a balloon or the like. 
         [0334]    Referring to  FIGS. 41 to 44  there is illustrated another valve device  151  according to the invention which is similar to that described above and like parts are assigned the same reference numerals. In this case the valve  1  is housed within a support structure or scaffold  102  and is placed into the lumen of a stent  140  as illustrated in  FIGS. 45 to 47 . The support structure may comprise a relatively short length (typically 40 mm) of a mesh made from a shape memory material such as Nitinol. The mesh may be formed by laser cutting and/or may be of woven construction. Deployment into the lumen of the host stent  140  is via self expansion from a radially collapsed state within a delivery catheter  130  as shown in  FIGS. 43 and 44 . The device  151  is held in place within the stent  140  by means of specific interaction mechanisms that increase the axial friction of the support structure  102 .  FIGS. 45 to 47  illustrate the interaction with the host stent  140 . In this embodiment the support structure  102  has a series of loops or protrusions  155  extending perpendicularly from its surface. These protrusions  155  engage with the structure of any host stent  140  by interlocking with the existing mesh as shown in  FIGS. 52 and 53 . The apical tip of each protrusion  155  is in this case rounded or designed so as to be non-traumatic to any tissue that may come into contact with the protrusion  155 . The intrinsic radial force of the support structure  102  as well as the flexural strength of the protrusions  155  interact to effect the retention performance of the support structure  102 . Thus the stiffness or flexural strength of the protrusion  155  and the radial force of the support structure  102  may be modified to change the interlocking capability and retention performance of the device. 
         [0335]    The valve device  151  is also readily radially collapsible by distal and proximal drawstrings  170 ,  171 . The distal drawstring  170  passes through eyelets  172  mounted to the support structure  102  at the distal end of the valve device  151 . The distal drawstring  170  has an accessible pull string  173  which, on pulling, pulls the drawstring  171  inwardly and thus reduces the diameter of the distal end of the support structure  102 . Similarly the proximal drawstring  171  passes through eyelets  175  mounted the support structure  102  at the proximal end of valve device  151 . The proximal drawstring  171  has an accessible pull string  177  which, on pulling, pulls the drawstring  171  inwardly and thus reduces the diameter of the proximal end of the support structure  102 . The pull strings  173 ,  177  can be readily gripped using a suitable instrument such as a grasper to draw the proximal and distal ends of the support structure  102  inwardly for ease of removal of the valve device  151 . 
         [0336]    Referring to  FIGS. 48 to 57  there is illustrated another valve device  200  according to the invention which is similar to that described above and like parts are assigned the same reference numerals. In this case the valve  1  is housed within a support structure or scaffold  102  and is placed into the lumen of a stent  140  as illustrated in  FIGS. 53 to 56 . The support structure  102  may comprise a relatively short length (typically 40 mm) of a mesh made from a shape memory material such as Nitinol. The mesh may be formed by laser cutting and/or may be of woven construction. Deployment into the lumen of the host stent  140  is via self expansion from a radially collapsed state within a delivery catheter  130  as shown in  FIGS. 50 to 55 . The device  200  is held in place within the stent  140  by means of specific interaction mechanisms that increase the axial friction of the support structure  102 .  FIG. 56  illustrates the interaction with the host stent  140 . In this embodiment the support structure  102  has a series of loops or protrusions  155  extending perpendicularly from its surface. These protrusions  155  engage with the structure of any host stent  140  by interlocking with the existing mesh as shown in  FIG. 56 . The apical tip of each protrusion  155  is in this case rounded or designed so as to be non-traumatic to any tissue that may come into contact with the protrusion  155 . The intrinsic radial force of the support structure  102  as well as the flexural strength of the protrusions  155  interact to effect the retention performance of the support structure  102 . Thus the stiffness or flexural strength of the protrusion  155  and the radial force of the support structure  102  may be modified to change the interlocking capability and retention performance of the device. 
         [0337]    The valve device  200  is also readily radially collapsible by distal and proximal drawstrings  170 ,  171 . The distal drawstring  170  passes through eyelets  172  mounted to the support structure  102  at the distal end of the valve device  200 . The distal drawstring  170  has an accessible pull string  173  which, on pulling, pulls the drawstring  171  inwardly and thus reduces the diameter of the distal end of the support structure  102 . Similarly the proximal drawstring  171  passes through eyelets  175  mounted the support structure  102  at the proximal end of valve device  200 . The proximal drawstring  171  has an accessible pull string  177  which, on pulling, pulls the drawstring  171  inwardly and thus reduces the diameter of the proximal end of the support structure  102 . The pull strings  173 ,  177  can be readily gripped using a suitable instrument such as a grasper to draw the proximal and distal ends of the support structure  102  inwardly for ease of removal of the valve device  200 . 
         [0338]    It will be noted that in the case of this device  200  the diameter of the support scaffold is relatively uniform and the proximal and distal ends  201 ,  202  of the device  200  are not tapered. We have found that the interengagement of the rounded protrusions  155  in interstices defined in the mesh structure of the stent  140  is sufficient to retain the device  200  in position in the stent  140 . Typically, the diameter of the expanded support structure  102  will be slightly larger, for example 1 to 5% larger than that of the host stent  140  at the desired deployment location to assist in maintaining the scaffold  102  in situ. 
         [0339]    In some cases, as illustrated in  FIG. 57  the devices of the invention such as the device  200  may be a radially collapsed state if it is described to re-position the valve device  200  with the stent  140  or to withdraw the device  200 , for example for replacement and/or for replacement of the host stent  140 . 
         [0340]    Thus, the collapsibility of the valves enables its optional removal by disengagement of the protrusions  155  from the host stent  140 , thus eliminating any axial friction associated with the host stent  140 . 
         [0341]    The valve of  FIGS. 1 to 57  may be relatively short and is typically less than 30 mm, less than 25 mm, less than 20 mm, less than 15 mm and is typically about 10.6 mm long with an outer rim diameter of 18 mm or about 11 mm long for an outer rim diameter of 20 mm. 
         [0342]    The valve may have any desired number of leaflets, for example the valve  300  illustrated in  FIGS. 58 to 65  has six valve leaflets  333 . These leaflets  333  are oriented perpendicular to direction of food flow to additionally allow greater distensibility of the valve aperture. 
         [0343]    Referring to  FIGS. 58 to 65  there is illustrated another valve device according to the invention. The device  300  comprises a valve  301  which can open automatically in one direction. 
         [0344]    The valve  300  comprises a polymeric valve body having a proximal outer support region with a rim  302 , six valve leaflets  303 , and a main body region  306  extending between the support rim  302  and the valve leaflets  303 . The valve leaflets  303  extend inwardly and distally and terminate at distal end faces  303  respectively. The leaflets each  303  have legs which extend at an included angle of 60° to each other. The adjacent pairs of legs co-apt to close the gap between the valve leaflets  303  when the valve is in the normally closed configuration. 
         [0345]    The valve  300  has two configurations. The first configuration is a normally closed configuration in which the valve leaflets  303  co-apt to close the valve. The second configuration is an open configuration in which the valve leaflets  303  are opened such that the leaflet leg pairs are opened and spaced-apart in response to a force F 1  to allow flow through the valve  300 . 
         [0346]    The various configurations of the valve  1  are illustrated in  FIGS. 58 to 65 . In the first or normally closed configuration the valve leaflets  303  co-apt. When a force F 1  is applied to the valve leaflets  303  the leaflet legs pairs open to allow flow to pass. When the force F 1  is removed the leaflets  303  return to the closed position under the inherent biasing of the polymeric material of the valve body. 
         [0347]    The valve leaflets  303  are reinforced in the region of co-aption. In this case, this is achieved by a local thickening of the polymeric material in this region. Similarly the support rim  302  is reinforced by a local thickening of the polymeric material. 
         [0348]    The region of co-aption of the valve leaflets  303  has an axial extent which is typically from 1 to 5 mm. This ensures positive co-aption of the leaflets across a significant interfacial area when the valve is in the normally closed configuration. The thickness of the leaflets at the region of co-aption is typically between 0.1 mm and 10 mm. 
         [0349]    The valve body  306  has a generally concave outer face and a generally convex inner face. 
         [0350]    The valve  300  of the invention returns to its original working position after being fully opened. This is accomplished without damaging the working valve. 
         [0351]    An important characteristic influencing the functioning of the valve  300  is the leaflet legs that impinge on one another. By varying the geometry and length of the leaflets  303  the valve  300  can be made to open at different pressures. Opening is also dependant on the elasticity and density of the material the device is made from. Additionally, the overall diameter and the diameter to which the leaflets open influence the opening force. 
         [0352]    The valve may be of any suitable biocompatible polymeric material. It may be of a biocompatible polymeric material having properties which allow the valve to function as described. 
         [0353]    The materials used for the production of this valve have a % elongation between 50% and 3000%. The material also has a tensile strength of between 0.01 and 5 MPa. Additionally the material could have an antimicrobial action to prevent colonisation when in-vivo. Additionally the material can be elastic or viscoelastic and can optionally be an open cell foam. The density of the material should be between 0.1 g/cm3 to 1.5 g/cm3. 
         [0354]    The valve  300  of the invention may be mounted to any suitable luminal prosthesis. The rim  302  of the valve provides a mounting ring for mounting within the prosthesis, for example, the valve  300  may be mounted to the stent by suturing the rim  2  to the stent mesh using sutures. 
         [0355]    Many emerging obesity treatments involve the placement of a tube into the duodenum, which restricts the absorption of certain nutrients at this point in the body. The resulting calorific deficit then results in weight loss. Some of these devices can cause the pyloric valve to be opened for prolonged periods thus causing rapid stomach emptying. During episodes of rapid stomach emptying the feeling of fullness is shortened and thus the patient eats more. 
         [0356]    We have found that by placing a valve device at or near the pylorus that can controllably restrict the rate of stomach emptying then a feeling of fullness or satiety can be gained. 
         [0357]    Referring to  FIGS. 66 and 67  there is illustrated a valve device  500  that can be retrospectively placed into an existing obesity treatment device such as a sleeve  501  which extends from a stomach  502  into the duodenum  503 . One such sleeve device is described in US2005/0125075A, the entire contents of which are incorporated herein by reference. The valve  500  functions to restrict the rate of stomach emptying. The positioning of the valve  500  within a pre-positioned sleeve  501  is illustrated in  FIGS. 66 and 67 . The valve  500  may be of the type described above and may be attached to a scaffold  505  as described above. 
         [0358]    Referring to  FIGS. 68 and 69  there is illustrated a valve  550  of the invention which in this case is placed in a pyloric sphincter  551  in order to control the rate of stomach emptying and thereby provide an enhanced feeling of satiety. This approach may be used, if example in association with gastic banding or other obesity treatment system. The valve  550  may be retained in situ by any suitable means such as anchors  552 . 
         [0359]    Alternatively, as illustrated in  FIGS. 70 and 71  the valve  550  may be located distal of the pyloric sphincter  551  to provide a further valve acting in series with the pyloric valve or sphincter. 
         [0360]    Referring to  FIGS. 72 to 77  there is illustrated a gastrointestinal implant device  600  which comprises a sleeve  601  for extending into the duodenum and an artificial valve  602  for placement at the pylorus  603  to control flow from the stomach  604  into the duodenum which is lined by duodenal sleeve  601 . The device  601  also comprises a support structure for the valve. In this case the support structure comprises a scaffold  605  to which the valve  602  is mounted. The support structure also comprises a luminal prosthesis  606  to which the scaffold is mounted. In this instance, the scaffold  605  is releasably mountable to the luminal prosthesis  606 . The sleeve  601  is mounted to the support structure and in this case to the valve and/or the scaffold  605 . 
         [0361]    In this case the support structure comprises a stent-like scaffold  605  and the luminal prosthesis  606 . The prosthesis  606  is for deployment at the pylorus and the scaffold  605  to which the valve  602  is mounted is releasably mountable to the pre-deployed luminal prosthesis  606 . The scaffold comprises engagement elements which are releasably engagable with the luminal prosthesis  606 . The engagement elements may comprise protrusions  607  which are releasably engagable with the luminal prosthesis. The luminal prosthesis  606  in this case comprises a mesh which may have a coating thereon. The protrusions  609  may engage with and in some cases penetrate the mesh. In the case of a coating on the mesh the protrusions  607  may penetrate the coating. 
         [0362]    In this embodiment at least a part of the implant device is removable for complete removal, re-positioning, or replacement. There is a release means for releasing the scaffold  605  from engagement with the prosthesis  606 . The release means in this case comprises means for reducing the diameter of at least portion of the scaffold. The release means may comprise a drawstring  611  extending around the scaffold  605 . In this case there is a first drawstring  611   a  extending around a proximal end of the support structure and a second drawstring  611   b  extending around a distal end of the support structure. For removal, the drawstrings are tightened by pulling on the loops  612  using a suitable instrument such as a grasper. 
         [0363]    Both the prosthesis  606  and the scaffold  605  may be of a shape memory material such as Nitinol and have a reduced diameter delivery configuration and an expanded deployed configuration. 
         [0364]    The prosthesis  606  in this case comprises a proximal flare  620  for location, in the expanded configuration at the antrum of the pylorus. The flare  620  assists in anchoring the prosthesis in position. The prosthesis  606  in this case also has a distal bulbous region  621  which assists in anchoring the prosthesis in position. The prosthesis  606  has a scaffold receiving region  622  which in this case is intermediate the proximal and distal ends of the prosthesis  606 . 
         [0365]    The scaffold  605  has a proximal region  630  to accommodate the valve  602  and a distal region  631  to accommodate the sleeve  601  in a retracted delivery configuration. The valve  602  may be attached to the scaffold  605  by sutures  632  and/or may be bonded, for example by adhesive bonding to the scaffold  605 . 
         [0366]    The sleeve  601  in this case is also attached to the scaffold  605  and/or to the valve  602 , for example by bonding and/or sutures. 
         [0367]    The valve  602  has a normally closed configuration and an open configuration in which the valve is opened for stomach emptying. The valve  602  is adapted to open automatically for stomach emptying and to return automatically to the closed configuration. The valve may be of a viscoelastic foam material such as the foam materials described in detail in this specification. The valve  602  is in this case similar to the valves described earlier and comprises an outer support region  640 , at least three valve leaflets  641 , and a main body region  642  extending between the support region and the valve leaflets  641 . The valve  602  has a region  643  of co-aption of the valve leaflets in the closed configuration to maintain the valve in the normally closed configuration. The region  643  of co-aption may extend for an axial length of at least 1 mm. 
         [0368]      FIG. 72  shows the luminal prosthesis  606  in a relaxed, pre-loading configuration.  FIG. 73  shows the scaffold  605 , valve  602  and sleeve  601 . The sleeve  601  is in a retracted configuration.  FIG. 74  shows the prosthesis  606  deployed at the pylorus and the scaffold  605 /valve  602 /sleeve  601  being inserted into the prosthesis  606 .  FIG. 75  shows the scaffold  605 /valve  602 /sleeve  601  deployed in the prosthesis  606 .  FIG. 76  is a view similar to  FIG. 75  with the sleeve  601  expanded into a deployed configuration extending through the duodenum.  FIG. 77  is a cross sectional view showing the valve  602 , support structure and sleeve  601  fully deployed. 
         [0369]    It will be appreciated that the sleeve may be configured in different ways in a retracted delivery configuration. Some examples are shown in  FIGS. 78 to 80 . In  FIG. 78  the sleeve  601  is folded somewhat like an accordion. In  FIG. 79  the sleeve  601  may be folded longitudinally and may subsequently be spirally wound. In  FIG. 80  the sleeve  601  has longitudinal pleats or folds and is also folded over transversely. 
         [0370]    The sleeve  601  may be of constant diameter along the length thereof or may be tapered (FIGS.  81 / 83 ) or may have a narrowed proximal section and a constant diameter distal section ( FIG. 82 ). 
         [0371]    The sleeve  601  may have a retaining means to assist in retaining the sleeve at a desired location. For example, as illustrated in  FIG. 81  the sleeve  601  may have a retaining ring  650  at or near the distal end of the sleeve. There may be a plurality of such retaining rings  650  which may be spaced-apart along the sleeve  601  as illustrated in  FIG. 83 . The rings  650  may be of different size and/or shape to suit the target anatomy. The retaining rings  650  may have a biasing means to bias them into an enlarged configuration. For example, the retaining ring  650  may be oversized with respect to the diameter of the sleeve  601 . There may be a release means such as a drawstring or the like to release the retaining ring  650  from the expanded deployed configuration. 
         [0372]    Referring to  FIGS. 84 to 89  an implant device according to the invention and an associated delivery system are illustrated. The delivery system comprises a delivery catheter  660  with a distal capsule  669  which contains the scaffold  605 , valve  602  and sleeve  601  in the retracted configuration. The delivery system includes a proximal expandable element provided by an inflatable proximal balloon  662  and a distal expandable element provided by a distal balloon  663 . The proximal balloon  662  provides a temporary seal with the proximal end  664  of the sleeve  601  at the proximal side of the valve  602 . The distal balloon  665  provides a temporary distal seal between a distal olive  666  and a distal end  667  of the sleeve  601 . An inflation fluid is introduced into the sleeve  601  between the proximal and distal balloons  662 ,  665 , the fluid causes the sleeve  601  to expand axially to the expanded deployed configuration. When the sleeve  601  is in the extended deployed configuration the distal balloon  665  is deflated, allowing the olive  666  to detach and travel distally. The rest of the delivery system can then be withdrawn proximally, leaving the implant device in situ.  FIG. 84  illustrates the luminal prosthesis or stent  605  with a 30 mm wide proximal flare placed across the pylorus with the proximal flare resting against the pyloric antrum. An endoscope with a delivery system is advanced into the stomach. The delivery device is controlled through the shaft of the endoscope and comprises a capsule that is positioned proximal to the endoscope. The capsule is advanced to the pre-placed stent.  FIG. 85  shows the stent, scaffold and valve with the sleeve in the retracted configuration. The distal olive  666  of the delivery system is also shown. 
         [0373]    Referring to  FIG. 86 , water is flushed through the delivery system to elongate the plastic sleeve, which passes through the duodenum past the ligament of trietz. 
         [0374]    Referring to  FIG. 87 , when the implant device is deployed the delivery system is removed and the distal olive  666  passes through the intestine. 
         [0375]    In the case of the delivery system of  FIGS. 84 to 89  the valve and scaffold are deployed before the sleeve is deployed. In this arrangement the proximal seal is provided by the proximal balloon which seals against the valve as illustrated in  FIG. 87 . 
         [0376]    Referring to  FIGS. 90 to 97  there is illustrated another delivery system. In this case the valve and scaffold are deployed after deployment of the sleeve. In this arrangement the proximal seal is provided by the proximal balloon  662  which in this case seals against the inner wall of a distal capsule  669 . The balloon  662  is not fully inflated in  FIGS. 91 ,  92  and  94 . A delivery catheter comprises an outer shaft  680  with a retraction hub  681  and an inner shaft  682 . The shaft has various lumens and at the proximal end there are various ports connected with the lumens. There is a proximal sleeve inflation port  683 , a distal tip balloon inflation port  684 , a proximal seal or plunger balloon inflation port  685 . There is also a guidewire port  686  (which is illustrated in  FIG. 96 ) for a guidewire  687 .  FIG. 97  shows the various lumens,—a water injection lumen  690  for deployment of the sleeve,—a proximal balloon inflation lumen  691 , a distal tip balloon inflation lumen  692  and a guidewire lumen  693 . A flexible tube  688  extends through a lumen  689  in the inner shaft  682 . The flexible tube  688  also extends through the proximal balloon  662  which in this case is of doughnut shape. The tube  688  has an outlet for inflation of balloon  665 . 
         [0377]    Referring to  FIG. 90  the capsule  669  is mechanically releasable from the outer sheath, for example through a screw thread connection  695 . In use, the shaft of the delivery system is inserted through the proximal end of a delivery channel of an endoscope. When the distal end of the shaft of the delivery shaft exits the distal end of the endoscope delivery channel the capsule is mounted to the distal end of the delivery shaft using the mechanical attachment which in this case is a screw-in attachment. 
         [0378]    In  FIG. 90  the sleeve/valve/scaffold implant device is in the retracted delivery configuration. The flexible tube  688  extends to the tip balloon  665  and has a hole through which air is delivered for inflation of the balloon  665 . The tube  688  is of a suitable flexible material such as a plastics, for example nylon. 
         [0379]    Referring to  FIG. 92 , the proximal balloon  662  is inflated to seal the sleeve  601  at the proximal end and the distal balloon  665  is inflated to seal the sleeve  601  at the distal end. Water is then flushed into the retracted sleeve  601  and by virtue of the seals  662 ,  665  at the proximal and distal ends, the water fills the sleeve  601 , causing it to extend. The sleeve  601  is shown in a partially extended configuration in  FIG. 92 . 
         [0380]    When the sleeve  601  has fully extended ( FIG. 93 ) the distal balloon  665  is deflated, allowing the tip  666  to float into the intestine for discharge. The proximal balloon  662  remains inflated and acts as a plunger to deploy the scaffold from the capsule  669 . The scaffold  605  engages with the stent  606  as described above and the delivery system is withdrawn as illustrated in  FIG. 94 . 
         [0381]      FIG. 95  illustrates the proximal delivery components. The retraction hub  681  is connected to the outer shaft to enable withdrawal of the outer shaft  680  over the inner shaft  682 . 
         [0382]      FIG. 98  is a graph of the pressure profile of fixed orifice restrictors with various size orifices. The restrictions were created using a 1 mm thick polyethylene membrane. Each orifice was created by drilling out the desired hole size followed by verification using a Vernier calliper. The flowrate through the test fixture was controlled at 7.86 g/sec with a fluid having a viscosity of 39,000 Cps. It will be noted that when a series of fixed diameter orifice restrictors are used to impede fluid flow, the resulting back-pressures generated have a distinctive pattern. The back-pressure initially rises sharply followed by a sustained gradual pressure rise until flow is stopped. This behaviour is illustrated by  FIG. 98  for 4 mm, 5 mm and 6 mm diameter restrictions. This is undesirable for use as a flow restrictor in the stomach because a constant rise in pressure as a function of flow might give rise to gastric distress and cramping. 
         [0383]      FIG. 99  is a pressure profile of various different restrictions. The 6 mm orifice is made as described above for  FIG. 98 . The pressure profile represented by interrupted lines is generated using a leaflet valve as described above with reference to  FIGS. 58-65 . The valve is of a viscoelastic foam material. The foam material is in this case a material described in Example 5 of the Group 1 materials described below. The density of the material was 0.9 g/ml. It can be seen from  FIG. 99  that a coapting valve of the above description enables the generation of a constant back-pressure over the duration of fluid flow. The valve is thus adapting to fluid flow to maintain a constant restrictive force independent of fluid flow therethrough. 
         [0384]    The performance of the valve can be tailored by adjusting the material density, this for example can be achieved by introducing more or less material into the valve forming mold, which subsequently expands to fill the cavity. Referring to  FIG. 100 , the valve was made using the same material as in  FIG. 99  but in this case the density was changed to approximately 0.76 g/ml. Through this modification it was possible to produce a valve that generated an initially high back-pressure and subsequently adapted to the fluid flow thus lowering the back-pressure. Such a valve has an initial barrier function followed by a steady state restriction. The valve impedes flow until a pre-determined set-point pressure after which the back pressure remains substantially constant thus providing a predictable stomach emptying rate. 
         [0385]    Various materials can be used for fabrication of the sleeve portion of the device. These materials can be for example; polyethylene, PTFE or FEP due to their low friction thus not impeding fluid flow therethrough. 
         [0386]    Referring to  FIGS. 101 and 102  a sleeve  750  according to the invention has means to visualise the deployment of the sleeve using a radiopaque marker. A radiopague ink or paint is used. Because of the chemical nature of the sleeve materials the adhesion of a coating is very difficult. A longitudinal pocket  751  is provided which may be created by overlapping a portion of the sleeve material. Into this pocket  751  is deposited a radiopaque material  752  such as a liquid silicon resin filled with BaSO4, which is subsequently cured. This facilitates a low profile and a fluoroscopically distinguishable marker for visualisation in the body. Referring to  FIG. 103  in this case the sleeve has a plurality of pockets  760  which may be arranged in any desired manner to facilitate visualisation, for example at particular locations. 
         [0387]    The duodenum begins at the pylorus and forms a curved region immediately distal to the duodenal bulb. This region, known as the descending duodenum, is where chyme begins to mix with digestive secretions from the ampulla of Vater. As the chyme begins to digest it is absorbed by the luminal surface of the duodenum. The sleeve functions to bypass this absorption mechanism. The length of the sleeve liner can be sufficient to reach the distal duodenum coincident with the ligament of treitz, where the duodenum meets the Jejunum. Alternatively the sleeve can be shorter and the inhibition of absorption through the duodenal lumen will be proportional to the length of the sleeve. Given that most of the adsorption in the duodenum happens between the ampulla of Vater and Jejunum the sleeve should at least be long enough to traverse the ampulla. In addition, when the sleeve does not extend into the ligament of treitz, the sleeve is more easily delivered as it is not required to navigate through the tortuosity of the ligament of treitz. The typical length of the sleeve may be 40 cm to 45 cm. 
         [0388]      FIG. 104  is an illustration of a host luminal prostheseis or stent  800  according to the invention. The stent  800  comprises a funnel shaped region  801  to be placed in the antrun of the stomach. The host stent shown in  FIG. 84  also has a funnel shaped region to be placed in the antrum of the stomach. Such a funnel shaped or flared region ensures that chyme flows through the lumen of the stent and not around the external surface of the stent. This is important as chyme being forced around the outside of the stent could cause compression and migration of the stent. 
         [0389]    The funnel region  801  is connected to a softer narrower region  802  that is designed to traverse the pylorus. This region  802  is sufficiently compliant to allow the pylorus to close in response to physiological pressures. 
         [0390]    This softer region  802  also has a means to allow coaxial connection of an obesity device such as a valve as shown in  FIG. 77 . The connection of an obesity device in the proximal part of the stent is important. By this methodology any drag force experienced by the obesity device due to food passage through the lumen can be transferred to other region(s) of the stent such as a distal bulbous region(s)  803  of the stent. The resulting compressive force can expand the bulbous region(s)  803  of the stent structure thus reinforcing the retention of the stent. 
         [0391]    Connecting the bulbous region  803  to a trans-pyloric funnel  801  helps to locate the stent in the anatomy and prevent rotation of the bulb  803  perpendicular to the axis of the duodenal lumen. 
         [0392]    The stent may also have a cylindrical region  804  that connects to the distal end of the bulbous region  803  for contacting with the tubular lumen of the duodenum. 
         [0393]    The stent is a self expanding stent. The self expanding stent may be produced by knitting, braiding or weaving. In one case the stent is of a braided structure. 
         [0394]    Self expanding braided or knitted stents can be made from either metal or synthetic polymers. If made from metal, a superelastic alloy is usually chosen because of the desired mechanical properties. These stents can be designed to exert significant radial force but at the same time be conformable and allow for the natural mechanical processes of digestion. 
         [0395]    The technology might be most appropriately used in the gastro intestinal tract as described above. 
         [0396]    One of the advantages of braided or knitted stents is that their radial diameter can be easily reduced to allow sheathing and delivery. This property is important when the stent is to be introduced into a narrow body lumen or even through the accessory channel of an endoscope. 
         [0397]    However, because of the woven structure, the reduced diameter stent is often substantially longer than when its diameter is allowed to return to it&#39;s nominal state. This in turn causes a problem during deployment, whereby the stent foreshortens as it expands radially, making accurate placement a challenge. The user of such stents must always balance the advantages of their clinical benefit with the difficulty of delivery. 
         [0398]    Because of the inter-relationship between the length and diameter of these stents, any force in the body that causes their elongation, will cause their diameter to shrink. This mechanical behaviour will ultimately result in loss of contact with the body lumen causing migration. Conversely, any force in the body that causes the stent to be longitudinally shortened will result in an axial expansion thus re-inforcing the stents position in the body lumen. 
         [0399]    Such a stent may elongate when a relative tensile force is applied to either end and may shorten when a compressive force is applied to either end. 
         [0400]    There are situations in which the use of a valve in a self expanding stent may be desirable and anatomical considerations may dictate that the valve be placed either at the proximal or distal end of the stent. A valve may experience a drag force from the flow of food through its lumen. If the valve is placed at the distal end of the stent, a tensile force may be created by the flow of food through the stent, whereas a compressive force could be created if the valve is placed at the proximal end of the stent. 
         [0401]    Although the latter is more desirable from a retention standpoint it may not always be possible to position a valve in the proximal stent. It follows that valves placed at the distal end of the stent give rise to a heightened risk of migration. 
         [0402]    The invention provides methodologies for the transfer of forces, experienced by distally placed valves, to the proximal region of a stent. Thus, a proximally placed valve could be made to exert a compressive force on the stent. 
         [0403]    The invention may be described broadly as follows: a stent that has an outer region  851  for contact with the body lumen, an inner region  852  for contacting with a valve (or such a prosthesis) and a connecting component for connecting the inner region to the proximal part of the outer region. One embodiment is illustrated by  FIG. 105 . The outer region may be contoured to fit the appropriate body lumen. The dimensions indicated in  FIG. 105  are particularly appropriate for a prosthesis which is to be located in the antrum of the stomach and extend through the pylorus. 
         [0404]    The connecting region may be formed by discrete struts, wires or other structures  853  as shown in  FIGS. 106 and 107 . Alternatively the inner and outer regions may be formed by one continuous stent folded so as to form coaxial inner and outer regions  851 , 852   FIGS. 108 and 109 . 
         [0405]    There are situations in which the placement of a valve and support structure in an already deployed self expanding stent (host stent) may be desirable. Such a valve component may anchor itself in the host stent by means of radial force, friction or by some mechanically interlocking mechanism. 
         [0406]    Any forces exerted on the stent and valve system that cause the stent to foreshorten and compress will result in an expansion of it&#39;s diameter. This behaviour would likely cause any coaxially located valve component to loose engagement with the inner lumen of the stent and thus migration would occur as shown by  FIG. 110 .  FIG. 110  illustrates longitudinal shortening of a stent  825  (such as a braided stent) resulting in migration of a valve device  826 . 
         [0407]    One aspect of the invention involves the addition of a non-distensible loop or series of loops  820  to the circumference of a self expanding stent restricting expansion of a section of a self expanding stent as shown by  FIGS. 111 ,  112  and  113 . The loops  820  which may be made from a flexible material such as a polymeric or metallic thread allow radial compression of the stent during loading but limit radial expansion to the pre-determined diameter of the loop. Exemplary materials are either monofilament or braided polypropylene suture or stainless steel wire. 
         [0408]    By using this methodology the valve component, which may be placed within the region with added loops, will not be displaced by any longitudinal forces on the stent. 
         [0409]    Referring to  FIG. 114  there is illustrated another endoluminal prosthesis  900  according to the invention. The prosthesis is similar to the prosthesis of  FIG. 113  and like parts are assigned the same reference numerals. The prosthesis is of braided mesh construction and comprises a proximal flare or umbrella region  801 , a bulbous region  803  and a duodenal region  804 . A transpyloric region  901  interconnects the proximal flare  801  around the bulbous region  803 . 
         [0410]    The proximal umbrella region  801  is of open mesh and is relatively soft to avoid tissue irritation. The periphery of the proximal flare is in this case at least partially coated with a suitable coating material. The coating in this region functions as a deployment aid as it prevents sticking between the adjacent regions when the stent is in a collapsed delivery configuration. The turning of the flare distally provides some axial drag which provides resistance against dislodgment in use, for example when located at the pylorus. 
         [0411]    The transpyloric region  901  is very soft and pliable to resist force transmission from the proximal flare  801  to the bulbous region  803 . The transpyloric region may be uncoated to allow some tissue ingrowth. 
         [0412]    The bulbous region  803  acts to assist retention of the device by engaging in the duodenal bulb. The mesh is flexible in this region to adapt to the anatomy in which it is deployed. A lower part of the bulbous region  803  may be coated to prevent tissue ingrowth. 
         [0413]    The duodenal region  804  is designed such that its diameter will not expand beyond a pre-seat limit. The braid/mesh has a weave which is more dense than the other regions as the duodenal region in this case is the region in which a valve  602  and associated scaffold  605  are deployed—as illustrated in  FIGS. 115 to 117 . The valve and scaffold may, for example, be as described above—such as those described with reference to  FIGS. 73 to 97 . 
         [0414]      FIG. 120  illustrates another luminal prosthesis  925  according to the invention which has some features similar to the prosthesis of  FIG. 109  having coaxial inner and outer regions  851 ,  852 . In this case the inner and outer regions  851 ,  852  are formed by one continuous precursor stent  935  ( FIG. 118 ) which is folded as illustrated in  FIG. 119 . The inner region  852  is in this case adjacent to the proximal end of the prosthesis and a scaffold and valve of the type previously described can be readily deployed.  FIG. 121  shows the luminal prosthesis of  FIG. 120  with a valve and scaffold in situ.  FIG. 122  illustrates an obesity treatment device according to the invention in situ which incorporate the device of  FIGS. 120 and 121 . The arrangement ensures that any movement of the valve is effectively isolated from any forshortening or otherwise of the outer region of the stent. 
         [0415]    Another luminal prosthesis  928  according to the invention is illustrated in  FIGS. 123 to 125 . This prosthesis  928  is similar to the prosthesis of  FIG. 107  and  FIGS. 124 and 125  illustrate how the inner part of the prosthesis is at least partially isolated from the outer part by virtue of the connection  853  which may for example define a region of at least partial articulation/hinging/pivoting. 
         [0416]      FIG. 126  illustrates another luminal prosthesis  925  according to the invention which is somewhat similar to the prosthesis of  FIGS. 109 . The functioning of the prosthesis  925  is diagrammatically illustrated in  FIGS. 127 to 129 . 
         [0417]    A similar prosthesis is illustrated in  FIG. 126  and the functioning of the device is diagrammatically illustrated in  FIGS. 127 to 129 . 
         [0418]    In some cases, as illustrated in  FIGS. 130 and 131  there may be an additional axially flexible connector such as at least one tether  930  between the inner and outer parts. 
         [0419]    Referring to  FIG. 132 , in this case a prosthesis  950  comprises a bulbous part  951  which is separate from a proximal flare part  952 . The parts  951 ,  952  may be interconnected by any suitable connector(s)  953  such as at least one tether. The proximal flare may have a partial transpyloric region to which a valve/scaffold may be mounted. 
         [0420]    Referring to digs  133  to  139 , there is illustrated another obesity treatment device  960  according to the invention. The device  960  comprises an external support  961 , a valve  962  mounted to an internal support  963  and a sleeve  964  which extends in use into the duodenum as described above. 
         [0421]    The external support  961  has a proximal flare portion  970  and a distal bulbous region  971 . The distal bulbous region and the proximal flare region are connected view a transpyloric cylindrical region. The radial force of the cylindrical legion is low to allow normal functioning of the pyloric sphincter. The proximal flare portion  970  is of open mesh construction and does not require a coating. It engages with the antrum of the stomach which retains it in place. At least a distal portion of the bulbous region  971  of the external support  961  is coated. 
         [0422]    The valve  962  is mounted to the internal support  963  and the internal support  963  in turn is engaged with the coated distal portion of the bulbous region  971  of the external support  961 . The internal support  963  has integral hoops  972  which engage in the mesh of the external support  961  to assist in retaining the scaffold  963  in situ. The internal support  963  is free to move relative to the external support  961  but does not impinge upon the tissue of the duodenal bulb. 
         [0423]    In use, when food is passing from the stomach through the valve  962  a proximal portion of the internal scaffold  963  moves relative to the external support  961  which causes axial force to be translated both distally and radially. The resultant force vector augments the radial force on the external support  961  and absorbs axial force. The proximal portion of the internal support  963  can move axially distally because it is not coupled to the external support  961 . The distal portion of the internal support  963  only interacts with the external support  961  and does not extend through the external support  961 . The inner support  961  does not engage with the wall of the duodenal bulb. 
         [0424]    The obesity treatment device does not interfere with the functioning of the pyloric sphincter. The pylorus functions normally whilst ensuring that the device is anchored in place. When food is passing through the valve the force applied is translated into a radial force on the duodenal bulb which is sufficiently pliant to distend and absorb this force. The device functions to retard the emptying of the stomach to give the user a prolonged feeling of saiety. 
         [0425]    In recent years there has been a significant upsurge in commercial activity related to implantable devices to treat obesity. Some of these devices are intended for use in the pylorus and duodenum and thus require some form of retention. Current retention modalities include the use of tissue penetrating barbs, which create ulceration and pain. This gastrointestinal implant device avoids the use of such barbs. 
         [0426]    This technology will find commercial application in the emerging area of obesity treatment for improving the retention of devices that will be exposed to the high forces associated with food flow through the GI tract. 
         [0427]    Various technologies which may be suitable for use in or in association with the device of the invention are described in the following US patent applications:
       U.S. Ser. No. 12/488,037 (published as US2010-0121462A);   U.S. Ser. No. 12/488,016 (now U.S. Pat. No. 8,029,557);   U.S. Ser. No. 12/487,991 (published as US2010-0121461A);   U.S. Ser. No. 12/971,458 (published as US2011-0190905A);   U.S. Ser. No. 13/493,904 (published as US2012-0310138A); and   U.S. Ser. No. 13/329,728 (published as US2012-0158026A)
 
the entire contents of all of which are herein incorporated by reference.
       
 
         [0434]    A first Group of biomaterials that are suitable for manufacturing a valve of the invention is described in our U.S. Ser. No. 12/488,047 (now U.S. Pat. No. 7,932,343) and WO2009/153769, the entire contents of which are herein incorporated by reference. A second Group of biomaterials that are suitable for manufacturing a valve of the invention is described in our U.S. Ser. No. 12/971,384 (published as US2011-0152395A) and WO2011/073967A, the entire contents of which are herein incorporated by reference. 
         [0435]    Various features of the invention are described in detail and illustrated herein. Appropriate features described with reference to one embodiment may be utilised in addition to and/or as a substitute for features described in other embodiments. 
         [0436]    The invention is not limited to the embodiments hereinbefore described, with reference to the accompanying drawings, which may be varied in construction and detail.