Abstract:
The invention relates to an implantable stomach prosthesis for surgically replacing or augmenting all or part of the antrum and/or pylorus of a stomach. The prosthesis controls the passage of food from the stomach to the small intestine. The prosthesis may be configured to chum ingested material and release it from the stomach through a prosthetic pyloric valve. At least one expandable member is arranged to be expanded to control the passage of food and/or to mimic the churning action of a patient&#39;s stomach. The prosthesis includes an outer support structure, a flexible inner member forming a conduit for the movement of material, and at least one expandable member located between the outer support structure and inner member. An implantable pump system is provided for inflating and deflating the expandable member(s).

Description:
This application is a Continuation application of U.S. Ser. No. 10/328,446, filed Dec. 23, 2002. 

   FIELD OF THE INVENTION 
   The invention relates to a stomach prosthesis for the mixing of materials in the stomach and/or the transport of materials through the stomach. In particular, the invention relates to a prosthetic stomach for replacing or augmenting a portion of the stomach, e.g., the pylorus and/or antrum. 
   BACKGROUND OF THE INVENTION 
   In general when food is ingested into the stomach, initially, the elastic upper portion or fundus accommodates the food and the fundus expands. As food enters and the fundus expands there is a pressure gradient created in the stomach between the fundus and the antrum (fundus pylori). A number of things occur at this time. Fluids tend to be pushed through the pylorus, which acts as a leaky valve. Peristaltic contractions move down the stomach from the fundus into the antrum to mix and break down food and propel small particles through the pylorus into the duodenum. In healthy human stomachs, peristalsis is believed to be controlled at least in part by a region of the stomach identified near the interface of the fundus and the corpus along the greater curvature. In this region, there are cells believed to govern the organs&#39; periodic contractile behavior that generate and propagate rhythmic electrical signals that correspond to the contractile behavior of the stomach. These characteristic contractions are believed to create, a pressure gradient between the fundus pylori (or antrum) and duodenum that relates to the rate of gastric emptying. When the contractions begin, the pylorus is generally closed, although fluid and small particles leak through the valve. As contractions or electrical activity corresponding to the contractions reach pylorus, the pylorus begins to open or relax. Thus, as the stomach churns and breaks down food in a healthy stomach, the pylorus opens. As this is occurring, there may be electrically activity in the duodenum as well. Retrograde electrical activity from the duodenum, i.e. contractions or electrical activity in the direction of the pylorus tends to cause the pylorus to close, thus preventing bile and pancreatic juices from backing up into the stomach. Accordingly, the opening and closing of the pylorus is influenced by input from both of its ends. 
   In a number of disease states or conditions, the contractions of the stomach and/or the opening and closing of the pylorus is irregular. Gastroparesis may result in insufficient contractions to chum food, move food through the pylorus, and/or open the pylorus, among other things, resulting in gastro retention of food. In another motility disorder known as dumping syndrome, the stomach empties at an abnormally high rate into the small intestine causing various gastrointestinal disorders. It is also believed that obesity may be treated by altering gastric motility or by causing the stomach to retain food for a greater duration to slow gastric emptying. 
   Accordingly, it would be desirable to provide a device and method for treating motility disorders of the stomach and/or obesity. 
   In some disease states, portions of the stomach and/or pylorus do not function properly or may require resection. Accordingly, it would be desirable to provide a prosthetic stomach for replacing or augmenting all or part of a stomach and/or pylorus. 
   SUMMARY OF THE INVENTION 
   The present invention provides a prosthesis device and method for replacing or augmenting all or part of the pylorus or antrum of the stomach. 
   In one embodiment, the prosthesis is designed to facilitate or expedite mixing or breaking down of food matter or liquids in the stomach. In another embodiment, the prosthesis is designed to control, facilitate or expedite movement of food matter or liquids through the pylorus and into the small intestine. In another embodiment, the prosthesis is designed to delay passage of food from the stomach and into the small intestine. 
   One embodiment of the present invention provides an implantable stomach prosthesis for surgically replacing all or part of the antrum and pylorus of a stomach. The stomach prosthesis is configured to churn ingested material and release it from the stomach through a prosthetic pyloric valve. In one embodiment a plurality of expandable members are arranged to be expanded in a sequence that mimics the churning action of a patient&#39;s stomach. The stomach prosthesis includes an outer support structure to be sewn on one end to the upper portion of the stomach and an opposite end to the duodenum. The prosthesis further includes an expandable member or members located within the outer support structure, and a flexible inner member forming a conduit for the movement of material. The flexible inner member is located within the outer member and the expandable member or members are located between the inner member and the outer support structure. The expandable members are expanded and contracted, or inflated and deflated to provide a pumping action that chums and breaks down the material and pumps it through the prosthetic pylorus. The expandable members are isolated from the material moving through the prosthesis by the inner member in which all the material is contained. Thus, the material does not get caught in the interstices around the expandable members. The prosthetic pylorus, at the exit point of the stomach, is also isolated from the material by the inner member. 
   In one embodiment of the invention, the implantable prosthesis further comprises an implantable pump system that includes a pump and a programmable controller. According to this embodiment, the expandable members are balloons configured to receive an inflation medium to expand the expandable members. The implantable pump system includes a reservoir of sterile inflation medium used to inflate the various expandable members. The reservoir may be implantable separate from the pump, e.g. in soft tissue. In general, the pump system is a closed system where the inflation medium is stored or transported as it is pumped from one inflation member to another. The prosthesis may be divided along its length into sections. A section may include a single expandable member or a plurality of expandable members that may be separately inflated or may share a conduit coupled to a single output port and valve on the pump. Preferably, each of the expandable members or sections of expandable members has an input port and valve coupled to the pump such that only one valve is opened at a time. However, the system may alternatively have more than one valve open at a time. 
   The controller controls the inflation and deflation of the expandable members by controlling the opening and closing of the valves coupled to each of the expandable members, and by controlling the pump direction and pressurization of the expandable members. In one embodiment, the inflatable members are inflated to a predetermined pressure. The pump may determine the inflation pressure by monitoring the pumping action or work of its motor. The inflation pressure may also be sensed by sensors that sense the pressure of the system, e.g. in the fluid header of the pump system. According to one embodiment, in a first churning mode, a first section of expandable members corresponding to a first section of the antrum is inflated, then a second adjacent section is inflated. The second section is inflated before the first section is deflated so that the material in the prosthesis cannot move back in an orad direction when the second section is inflated a number of subsequent inflation member sections may then be inflated and deflated in a manner that mimics the stomach&#39;s mixing and churning of food material. In this mode, the prosthetic pyloric valve may be partially open to permit liquid and small particles to pass through the pylorus into the small intestine. 
   A second mode may be employed to empty the stomach. According to one embodiment of this second mode, a first section of expandable members corresponding to a first section of the antrum is inflated, then a second adjacent section is inflated. The second section is inflated before the first section is deflated so that the material in the prosthesis cannot move back in an orad direction when the second section is inflated. The first section is then deflated. Then the third section is inflated, etc. until the section adjacent the pylorus is inflated. According to this mode the pylorus may be opened further to permit passage of more food material. If the food has not been sufficiently broken down to pass through the pylorus, the churning mode may be repeated. 
   In either of these modes sensors may be employed on each side of the pyloric valve to sense pressure or changes in pressure. The pyloric valve may be relaxed or tightened depending on the sensed pressure. For example, if there is an increased pressure from the duodenum side of the pyloric valve, the pyloric valve is tightened to prevent back flow of material, e.g., bile, from the small intestine. If there is an increased pressure from the stomach side of the pyloric valve, the valve may be relaxed to permit movement of material from the stomach into the small intestine. 
   The controller may also control selection of a section of the stomach organ for the churning or breaking down of material. The controller may control selection of sections of the organ for peristaltic movement or moving material through the stomach organ. Accordingly, sections may be selected according to a desired sequence of the section actuation. The controller may be preprogrammed to control the peristalsis pattern or may be reprogrammed externally or in response to sensed conditions at various locations in the prosthesis. For example the sensors may sense presence or absence of material in the prosthesis and may direct a pattern of peristaltic movement in the various sections accordingly. 
   In one embodiment, a single electromechanical device actuates the opening and closing of the valves according to the sequence. The valve actuator selectively actuates a particular valve at a given time according to instructions from the controller. 
   The pump and the valve actuating mechanism may be powered through a coil inductively coupled transcutaneously to an external power source, or by a battery rechargeable through such coil and external power source. According to one embodiment, a user positions and actuates the external power source to actuate the prosthesis. The electronics unit may be powered by a rechargeable or replaceable battery as the controller consumes relatively little power in its operation. 
   In another embodiment, the prosthesis is a prosthetic pyloric valve. According to this embodiment, a pyloric valve is replaced with a prosthesis comprising an outer member, an inner member and one or more sections of inflatable members between the outer and inner member. The inflatable member sections are selectively inflated and deflated to control the opening and closing of the pylorus. The prosthesis may include pressure sensors on opposite ends of the valve. The pressure sensors sense pressure in the stomach and duodenum and the opening and closing of the valve is adjusted accordingly. For example, a pressure increase from the duodenum would trigger the closure of the valve to prevent backflow of material into the stomach. An increasing pressure from the stomach may trigger a relaxing of the valve to permit materials to pass out of the stomach. 
   In another embodiment, the natural pyloric valve is augmented by implanting a pyloric prosthesis in the duodenum adjacent the pyloric valve. In this embodiment, the prosthesis may act to prevent material from passing into the small intestine even when the natural pyloric valve is open. Thus the augmented prosthetic pylorus may be used to retain food in the stomach for a greater length of time, e.g., to prevent gastric dumping or to treat obesity. According to this embodiment, one or more inflatable members sections are provided between an inner member and an outer member. The outer member is sutured onto the inside of the duodenum intestinal wall, just below the pylorus. Inflation conduits extend from the expandable member out of the outer support member and intestine. The conduits are coupled to an implanted pump that inflates and deflates the inflation member sections as desired to retain or pass food. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a side view of a prosthetic stomach device attached to a stomach according to an embodiment of the invention. 
     FIGS.  1 B and  1 B- 1  are schematic side views of the prosthesis of  FIG. 1A  in a relaxed position, including a pump, valve actuating device and controller. 
       FIG. 1B-2  is an enlarged view of a portion of the prosthetic stomach of  FIG. 1B  illustrating the wire sensors. 
       FIG. 1C  is a cross-section of  FIG. 1B  along the lines  1 C- 1 C. 
       FIG. 1D  is a cross-section  FIG. 1B  along the lines  1 D- 1 D. 
       FIG. 1E  is a schematic side view of the prosthesis of  FIG. 1A  a first actuated position. 
       FIG. 1F  is a schematic side view of the prosthesis of  FIG. 1A  in another actuated position. 
       FIG. 1G  is a schematic side view of the prosthesis of  FIG. 1A  in another actuated position. 
       FIG. 1H  is a schematic side view of the prosthesis of  FIG. 1A  in another actuated position. 
       FIG. 1I  is a schematic side view of the prosthesis of  FIG. 1A  in another actuated position. 
       FIG. 1J  is a schematic side view of the prosthesis of  FIG. 1A  in another actuated position. 
       FIG. 2A  is a side view of a prosthetic stomach device attached to a stomach according to an embodiment of the invention. 
       FIG. 2B  is a schematic side view of the prosthesis of  FIG. 2A  in a relaxed position. 
       FIG. 2C  is a schematic side view of the prosthesis of  FIG. 2A  in a closed position. 
       FIG. 3A  is a schematic side view of a prosthetic stomach device attached to a stomach according to another embodiment of the invention. 
       FIG. 3B  is a schematic side view of the prosthesis of  FIG. 3A  in a relaxed position. 
       FIG. 3C  is a schematic side view of the prosthesis of  FIG. 3A  in a closed position. 
       FIG. 4  is a schematic of a miniature valve-actuating device for controlling the valves of the pump of an embodiment of the invention in a first position with a valve closed and a rotational position in which none of the openings of the device are aligned with a valve. 
       FIG. 4A  is an end view of the device as illustrated in  FIG. 4  in the first position. 
       FIG. 5  is a schematic of the valve-actuating device of  FIG. 4  in a second position. 
       FIG. 5A  is an end view of the device illustrated in  FIG. 5  with the valve open and an inflation being inflated. 
       FIG. 6  is a schematic of the micro valve-actuating device in the rotational position of  FIG. 5  with the valve closed and the inflation member in an inflated position. 
       FIG. 6A  is an end view of the device illustrated in  FIG. 6 . 
       FIG. 6B  is a schematic side cross-section of the cylinder and rod of  FIG. 6 . 
       FIG. 6C  is a cross section of  FIG. 6B  along the lines  6 B- 6 B. 
       FIG. 6D  is a cross section of  FIG. 6B  along the lines  6 D- 6 D. 
       FIG. 6E  is a top view of the cylinder of  FIG. 6 . 
       FIG. 6F  is a cross section of a portion of the cylinder as illustrate in  FIG. 6E  along the lines  6 F- 6 F. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1A , a prosthetic stomach  30  is illustrated attached to the upper portion  201  of the stomach  200  at the orad end portion  33  of the prosthetic stomach  30  and to the duodenum  202  at the aborad end portion  34  of the prosthetic stomach  30 . An implantable pump system  40  ( FIG. 1B-1 ) and electronics unit  50  ( FIG. 1B-1 ) are contained in a housing  80  coupled to the prosthetic stomach  30 . The pump system  40  and electronics unit control the inflation and deflation of inflatable members  36   a - g  ( FIG. 1B ) that are inflated and deflated according to a desired protocol, to actuate the stomach prosthesis  30 . A bladder  49  of the pump system  40  is located externally of the housing, within the patient&#39;s soft tissue. 
   A schematic of the prosthesis of one embodiment is illustrated in  FIGS. 1A-1J . The prosthesis includes a prosthetic stomach  30 , a hermetically sealed pump system  40  and a hermetically sealed electronics unit  50  including a controller  51  for controlling the pump system  40 . The pump system  40  and electronics unit  50  may be contained in the same housing  80  illustrated in  FIG. 1A  or may alternatively be separate. 
   The prosthetic stomach  30  includes an outer support member  31 , a series of inflatable member sections  36   a - g , and an inner member  32 . The inflatable member sections  36   a - g  each comprise a plurality of opposing inflatable members that when inflated act to close together and squeeze the inner member  32 . Each inflation member section  36   a - f  corresponds to a particular section a-f of the prosthetic stomach  30 . In this particular embodiment, inflatable member sections  36   a - d  each comprise three inflatable members where the prosthetic stomach  30  is larger (See  FIG. 1C ), and inflatable member sections  36   e - g  each comprise two inflatable members where the prosthetic stomach  30  is narrow (See  FIG. 1D ). 
   The outer support member  31  comprises a flexible, relatively inelastic material such as, for example, polyethylene or polyurethane, and provides structural support for the prosthetic stomach  30  (alternatively an elastic material may be used). The prosthesis sections a-f and inflatable member sections  36   a - f  form an antrum portion  37  of the stomach. Section g and inflatable member section  36   g  form a prosthetic pyloric valve  38  at the aborad end portion  34  of the stomach prosthesis  30 . The inner member  32  comprises a thin-walled, non-elastic flexible material such as polyethylene or polyurethane. The inside of the inner member  32  may be coated with an antibiotic surface, such as a silver coating, to reduce bacterial growth. The inner member  32  is attached to the outer support member  31  at the orad end portion  33  and the aborad end portion  34  of the prosthetic stomach  30  (for example, by welding) to provide an isolated cavity where material is mixed, broken down and passed through the pyloric valve  38 . The orad end portion  33  of the outer support member  31  includes an extended portion for suturing the outer support member  31  to the upper portion of the stomach  201 . The inflatable member sections  36   a - g  are located between the outer support member  31  and the inner member  32 . The inner member  32  floats relatively loosely within the outer support member  31  so as to permit movement including the inflation and deflation of the inflatable member sections  36   a - g.    
   Although sections  36   a - g  are illustrated, the number of inflation member sections depend on a selected prosthesis size, the size of the patient or the amount of the stomach to be replaced. 
   Each of the inflation members of a section converge together when inflated, to churn or move material in the prosthetic stomach  30 . Each inflatable member section  36   a - g  is coupled to and is in fluid communication with a corresponding one of conduits  39   a - g , respectively. Conduits  39   a - g  are used to selectively deliver inflation medium to and from inflatable members  36   a - g  by an implanted pump system  40 . 
   As illustrated in  FIG. 1B , a controller  51  of an electronics unit  50  controls the implantable pump system  40  to selectively inflate and deflate inflatable member sections  36   a - g . The pump system  40  includes a bi-directional hydraulic pump  41  having an intake  47  coupled to a fluid reservoir  49  and an output  44  in fluid communication with a header  45  having fluid ports  45   a - g . The bi-directional pump  41  may be configured in a number of ways to provide pumping in two directions, for example, by controlling a series of valves that direct fluid into or out of the reservoir  49  or by providing a DC powered reversible pump. The fluid reservoir  49  contains a sterile, radiopaque inflation medium sufficient to inflate two sections of inflation members  36   a - g  or a combination thereof at a given time. The fluid reservoir  49  may be implanted at a location adjacent to or away from the pump system  40  (e.g. in soft tissue) or alternatively may be included with the pump system. 
   Each fluid port  45   a - g  is coupled to a respective valve  46   a - g , which is coupled to a respective conduit  39   a - g . Each conduit  39   a - g  is coupled to a corresponding inflation member pair  36   a - g . The valves  46   a - g  are controlled by a valve actuating device  300  which operation is controlled by the controller  51  of the electronics unit  50 . The valves  46   a - g  in this particular embodiment are controlled by a electromechanical device described in more detail with reference to  FIGS. 4-6F . Alternative valve actuating mechanisms are also contemplated, for example, individually operated bistable solenoid valves may be used. 
   A pressure transducer  48  is located between the output  44  of the pump  41  and the header  45 . The pressure transducer  48  senses the pressure of the fluid of a particular section of inflation members when the corresponding solenoid valve of the corresponding port is in an open position. The pressure transducer  48  is coupled to the controller  51 , which controls the pump  41  in response to a sensed pressure. 
   Sensors  53  and  54  are located on opposing ends of the inflation member section  36   g  (forming the pyloric valve  38 ) between the outer support member  31  and the inner member  32 . Sensor  54  is located on the antrum side while sensor  54  is location on the duodenum side. The sensors  53 ,  54  are coupled to the electronics unit  50  by leads. The sensors  53 ,  54  are used to sense pressure on either side of the valve  38 . When the pressure increases or reaches a threshold level on the stomach side of the valve  38 , the pyloric valve is relaxed by partially deflating the inflation member section  36   g . When the pressure increases or reaches a threshold level on the duodenum side of the valve  38 , the valve  38  is tightened to prevent backflow into the stomach. The pressure sensors  53 ,  54  are coupled to a controller which can compare the pressures sensed by each of the sensors  53 ,  54  and provide a control signal that will control the resulting desired inflation or deflation of the valve  38  based on the sensed pressures or pressure differentials. The relative pressure on each side of the valve  38  as compared to the other side of the valve  38  may be used to control the valve  38  as well. 
   The electronics unit  50  includes a controller  51  and a battery  52  powering the controller  51 . The controller  51  is programmed to control the action of the various elements of the prosthesis and to respond to various sensed conditions. The controller  51  is coupled to the pump system  40  and controls when and in which direction the pump  41  is actuated. The controller  51  is also coupled to a valve-actuating device  300  that opens and closes the valves  46   a - g  according to a program stored in the controller  51 , thereby sequentially inflating and deflating inflation member sections  36   a - g . According to one embodiment, only one valve is open at a time. The controller  51  also includes a telemetry coil  59  for communicating information to and receiving information from an external device. The external device may be used to program operation parameters into the controller  51 . The external device may also receive signals from the controller  51  or electronics unit  50  representative of various sensed conditions, e.g., pressure or system leaks. The external device may program or reprogram the controller  51  based on sensed parameters or other patient conditions. An external device may also power the pump  41  and the valve-actuating device  300  through an electronics unit  70  comprising an electromagnetic coil  71  for inductively receiving power from an external source. The electromagnetic coil  71  is coupled to the electronics unit  50 , which includes a voltage regulating circuit. The electronics unit  50  and controller  51  control the pump  41  by powering the pump and controlling the valve actuating device  300 . The voltage regulating circuit of the electronics unit  50  operates to convert a high frequency AC signal to a regulated voltage signal that powers the pump  41  and valve actuating mechanism  300 . Alternatively, coil  59  may be used for both powering the pump and electronics unit  50  and for bi-directional telemetry communication. 
   The prosthetic stomach  30  also further includes wires  55   a - f  ( FIG. 1B-2 ) embedded in the prosthetic stomach  30  along its length and communicating with the electronic circuit  50 . The wires  55   a  and  55   d  are located in the outer tube  31  each between layers  31   i  and  31   o  and on opposing sides along the prosthetic stomach  30 . Wires  55   b  and  55   e  are exposed between the inflation member pairs  36   a - e  and the outer tube  31  on opposing sides along the prosthetic bowel  30 . Wires  55   c  and  55   f  are located in the inner tube  32  along the stomach  30  between layer  32   i  and  32   o . Wire pairs  55   a  and  55   d  form an open circuit as do wire pairs  55   b  and  55   e , and wire pairs  55   c  and  55   f . The electronic circuit  50  is configured to sense a large drop in impedance in one or more of the pairs wires  55   a - f , where a fluid closes the circuit of one or more of the wire pairs indicating potential leakage of fluid into, out of or within the stomach  30 , e.g from material external the prosthetic stomach  30 , material within the inner member  32  of the stomach  30  or from an inflation member, or otherwise. In particular, a low impedance may be detected by the controller  51 , which is configured to sense impedance changes in the wires  55   a - f . The impedance of the pairs of wires  55   a - f  is periodically monitored by the controller  51 . If a leak is detected a patient alarm may be triggered, e.g., by telemetrically delivering an alarm signal from the electronics unit  50  to an external device. Furthermore, the location or cause of the leak may be determined by which wires  55   a - f  have changed impedances. The wire pairs may be placed in different configurations within layers  31   i ,  31   o ,  32   i ,  32   o  or between the inner  32  and outer members  31 , for example, they may be is parallel spiraled configurations to maximize the sensing of potential leaks. 
   The prosthetic stomach  30  also includes a conduit  56  through the prosthetic bowel  30 , into a port  57  inside the inner member  32  for delivery a digestive enzyme, antibiotic material, or the like from a reservoir  58 . The reservoir  58  is coupled to the controller  51  and may include a pump controlled by the controller  51  that provides a periodic or otherwise actuated (e.g. by a patient) injection of a material into the inner member  32 . The reservoir  58  may also be implanted in soft tissue or may be included with the housing  180 . 
   The prosthetic stomach  30  is illustrated in  FIG. 1B  in an inactive position in which a patient may ingest food and food may move from the fundus into the antrum portion  37  of the prosthetic stomach  30 . In this position the pyloric valve  38  at the aborad end portion  34  is in a closed position with inflation member section  36   g  inflated. The inflation member sections  36   a - f  of the antrum portion  37  are relaxed and deflated. 
     FIGS. 1E-1J  illustrate a sequence of mixing food and emptying the prosthetic stomach  30  of one embodiment of the invention. In  FIG. 1E  the valve  46   a  is opened and the pump  41  pumps inflation medium from the reservoir  49  into the inflation member section  36   a  through the conduit  39   a . The inflation member section  36   a  is inflated to a predetermined pressure as sensed by pressure transducer  48  or alternatively as sensed by the motor. Once the inflation member section  36   a  is inflated, the valve  46   a  is closed by the valve actuating mechanism  60  ( FIG. 1B ). Inflation of the inflation member section  36   a  closes the orad end portion  33  of the prosthetic stomach  30  from the upper portion of the stomach  201 . Material within the prosthetic stomach  30  is thus contained in the antrum portion  37 . 
   Next, as shown in  FIG. 1F , inflation member section  36   b  is inflated to grind material in the prosthetic stomach  30 . The inflation member section  36   b  is inflated by opening the valve  46   b  and inflating by pumping fluid from the reservoir  49  into inflation member section  36   b  through conduit  39   b . Thus, the materials remain in the antrum portion  37  without allowing them to move back in the direction of the inflation member pair  36   a . The valve  46   b  is then closed. The inflation member section  36   b  may then be deflated and other inflation member sections  36   c - 36   f  may be inflated and deflated according to a predetermined sequence to mix material in the antrum portion  37 . As shown in  FIGS. 1E and 1F , the pyloric valve  38  is only slightly open, permitting fluids or small particles to pass through. 
   After some mixing has occurred, as illustrated in  FIG. 1G , the pyloric valve  38  may be further relaxed by partially deflating inflation member section  36   g . Thus as inflation members are inflated in an aborad direction, material that is sufficiently broken down may pass through the pyloric valve  38 . In  FIG. 1G , inflation member section  36   b  is inflated. The inflation member  36   a  has been deflated from a inflated position similar to that of  FIG. 1F  by selecting valve  46   a , reversing the pump direction, pumping the inflation medium out of the inflation member section  36   a  back to the reservoir  49  and closing the valve  46   a . As shown in  FIG. 1H , inflation member section  36   c  is next inflated to advance material further through the prosthetic stomach  30 . Before the adjacent inflation member section  36   b  is deflated, the inflation member section  36   c  is inflated by opening the valve  46   c  and by pumping fluid from the reservoir  49  into inflation member section  36   c  through conduit  39   c . Thus, any materials are advanced further toward the pyloric valve  38 . The valve  46   c  is then closed. 
   Referring to  FIG. 1I , inflation member section  36   b  has been deflated by selecting the valve  46   b , reversing the pump direction and pumping the inflation medium out of the inflation member pair  36   b  and closing the valve  46 . The inflation member section  36   d  is inflated by selecting the valve  46   d  and pumping inflation medium into the inflation member section  36   d . A number of inflation member sections may be provided in the prosthetic stomach  30  and the sequence of inflating and deflating the inflation members continues until the last inflation member sections  36   e  and  36   f  are inflated as illustrated in  FIG. 1J . 
   If the materials have not been sufficiently broken down to pass through the pyloric valve  38  the mixing cycle may be repeated until they are sufficiently broken down. 
     FIGS. 4-6F  illustrate a valve-actuating device  300  according to an embodiment of the invention. The valve-actuating device  300  comprises a cylinder  310  having a length Lc aligned parallel with the length Lh of the header  45  of the pump  41  and adjacent the valves  46   a - g . The cylinder  310  includes a plurality of openings  320   a - g , spaced a defined distance along the length Lc of the cylinder  310  with respect to the other openings so that each opening is aligned lengthwise with a corresponding one of the valves  46   a - g . Each opening  320   a - g  is also spaced a defined discrete distance circumferentially from the other openings. The cylinder  310  is coupled to a stepper motor  330  that rotates the cylinder  310  according to instructions from the controller  51  ( FIG. 1A ) into discrete circumferential positions to interfacingly align a selected opening with a corresponding selected valve. Thus, the cylinder  310  may be rotated to discrete positions wherein in each position one of the openings  320   a - g  is interfacing a corresponding one of the valves  46   a - g  to be actuated. 
   A valve is actuated by a peg extending out of an interfacing opening in the cylinder  310  to engage and move the valve into an open position. Each opening  320   a - g  in the cylinder  310  includes concentrically moveable peg  321   a - g  respectively. Each of the pegs  321   a - g  is capable of being partially advanced in a circumferential direction out of the corresponding opening  320   a - g  in the cylinder  310 . When interfacing with a corresponding valve  46   a - g , a corresponding peg  321   a - g  may be advanced to engage and open the corresponding valve  46   a - g  to open it. 
   Once a valve is selected and the controller  51  instructs the stepper motor  330  to rotatably position the cylinder  310  accordingly, an actuating rod  323  is advanced through the cylinder  310  to engage and advance the corresponding aligned, interfacing peg out of the cylinder  310  to open the corresponding valve. 
   The actuating rod  323  slidably extends axially through an axial opening  313  in the cylinder  310 . The rod  323  is coupled to a solenoid  328  that moves the rod  323  between two positions: a first resting position ( FIG. 4-4A ,  FIGS. 6-6F ) and a second valve actuating position ( FIG. 5-5A ). The solenoid  328  advances and retracts the rod  323  to and from a valve actuating position. The actuating rod  323  moves in a direction generally perpendicular to the circumferential sliding direction of the pegs  321   a - g . The actuating rod  323  includes a central rod  324  and a plurality of staggered fins  325   a - g  having cammed surfaces  326   a - g . In the first position, the fins  325   a - g  are staggered in a lengthwise relationship between the valves  46   a - g  and a second position, the fins  325   a - g  are generally aligned in a lengthwise relationship with the valves  46   a - g . The cammed surfaces  326   a - g  are arranged so that when the rod  323  is advanced to the second position, a corresponding one of the cammed surfaces  326   a - g  will engage a corresponding one of the pegs  321   a - g  to move the corresponding one of the pegs  321   a - g  circumferentially out of a corresponding one of the openings  320   a - g.    
   The axial opening  313  through the cylinder  310  includes a central rod portion  314  for receiving the rod  323  and a fin portion  315  for receiving in the fins  325   a - g . The central rod portion  314  extends axially through the cylinder  310 . The fin portion  315  of the axial opening  313  includes open portions  316   a - g  staggered in a lengthwise relationship between the valves  46   a - g . Each open portion  316   a - g  is open within the rod opening  313  about the circumference of the cylinder  310  so that when the rod  323  is in the first position, the cylinder  310  is free to rotate without interference of the fins  325   a - g . The fin portion  315  also includes a plurality of slits  317   a - g  circumferentially spaced from the other slits, wherein each slit extends longitudinally through the cylinder, between each of the open portions  316   a - g  and perpendicularly through a corresponding one of the openings  320   a - g.    
   The fins  325   a - g  are aligned in a position with the circumferentially extending top portions facing the header  45 . The cylinder  310  may be rotated when the rod  323  and fins  325   a - g  are in the first position. The cylinder when rotated to one of its discrete positions aligns a corresponding slit with the fins so that in the second position the fins advance through that slit. When the fins  325   a - g  are moved into the second position, the fins  325   a - g  extend through the slit corresponding to the opening that is positioned in alignment with a corresponding valve. In each discrete position the fins  325   a - g  are aligned with a slit permitting the corresponding fin to slide into the opening and engage the pin moving the pin out of the opening engaging the correspond valve with which it is aligned, thus actuating the corresponding valve. Each peg  321   a - g  is biased by a corresponding spring ( 329   a  only is shown) into a position circumferentially into the opening so that when the fins are retracted (e.g.  FIG. 6 ), the pin moves back into the opening. 
   The controller  51  controls the timing and actuation of the cylinder  310  rotation and the solenoid  328  positioning. Referring to  FIG. 4 , the cylinder  310  is rotated to a position in which none of the pegs are aligned with valve  36   a . The rod is in a first position in which the cylinder  310  may rotate freely. The cylinder  310  is then rotated as illustrated in  FIG. 5  so that the opening  321   a  is aligned with the valve  46   a . The rod  323  is advanced so that the fins  325   a - g  extend through the slit  317   a . Fin  325   a  extends into the opening  320   a  that is aligned with the slit  325   a  and the cammed surface  326   a  of the fin  325   a  engages the peg  321   a  and advances it out of the opening  320   a  to actuate valve  46   a . The valve  46   a  is opened and the pump  41  pumps fluid from the reservoir  49  into the inflatable member pair  36   a . As illustrated in  FIG. 6 , the rod  323  is then retracted releasing the peg  321   a , which is biased by spring  329   a  into the cylinder opening  320   a , and the valve  46   a  is closed, leaving the inflation member pair  36   a  inflated. 
   Referring to  FIGS. 2A-2C  another embodiment of the invention is illustrated. A prosthesis includes a prosthetic pylorus  130  and a housing  180  containing a pump system similar to the pump system  40  described above with reference to  FIGS. 1A-1J . The prosthetic pylorus  130  includes an outer support member  131 , a series of inflatable member sections  136   a - b  and an inner member  132 . The outer support member  131  comprises a flexible, relatively inelastic material such as, for example, polyethylene or polyurethane, and provides structural support for the pylorus (elastic materials may be used as well.). The inner member  132  comprises a thin-walled, non-elastic flexible material such as polyethylene or polyurethane. The inner member  132  may be coated with an antibiotic surface, such as a silver coating, to reduce bacterial growth. The inner member  132  is attached to the outer support member  131  at the orad end portion  133  and the aborad end portion  134  of the prosthetic pylorus  130  (for example, by welding) to provide an isolated conduit through which material may pass. The orad end portion  133  and aborad end portion  134  of the outer support member  131  include relatively thicker portions for suturing the orad end portion  133  of the outer support member  131  to the stomach  100  and aborad end portion  134  of the outer support member  131  to the small intestine  101  as shown in  FIG. 2A . The inner member  132  defines a conduit through which material pass from the stomach  100  into the small intestine  101 . The inflatable member sections  136   a - b  are located between the outer support member  131  and the inner member  132  with the inner member  132  floating relatively loosely within the outer support member  131  so as to permit the inflatable member sections  136   a - b  to expand and contract. 
   The prosthesis  130  is implanted to replace the pylorus of the stomach. The inflatable member sections  136   a - b  and the inner member  132  form a valve  138 . The inflatable members  136   a - b  are attached to the inside of the outer support member  131  between the outer support member  131  and the inner member  132  along the length of the prosthesis  130 . According to this embodiment, the inflatable member section  136   a  forms an orad inflatable member pair and the inflatable member section  136   b  forms an aborad inflatable member pair. Each section of inflatable members converges together when inflated, to close the valve  138 . The valve  138  is actuated by inflating sections  136   a - b , which causes the inner member  132  to squeeze together to seal the conduit closed. 
   Each section  136   a - b  is coupled to and is fluid communication with a corresponding respective one of conduits  139   a ,  139   b . Conduits  139   a ,  139   b  are used to selectively deliver inflation medium to and from sections  136   a - b  by an implanted pump system  140  (and valve actuator) and electronics unit  150  similar to the pump system  40  (and valve actuator  300 ) and electronics unit  50  described above with reference to  FIGS. 1A-1J  and  FIGS. 4-6F . 
   Referring now to  FIGS. 3A-3C , a supplemental pyloric valve  230  is illustrated implanted adjacent a pylorus  205  and in the duodenum  206 . The supplemental pyloric valve  230  is coupled to an implanted housing  280  including a hermetically sealed pump  241  and controller  251  operating in a similar manner as pump system  40  (and valve actuator  300 ) and electronics unit  50  described above with reference to  FIGS. 1A-J  and  FIGS. 4-6F   
   The supplemental pylorus  230  includes an outer support member  231 , a series of inflatable members sections  236   a - b  and an inner member  232 . The outer support member  231  comprises a flexible, relatively inelastic material such as, for example, polyethylene or polyurethane, and provides structural support for the pylorus (elastic materials may be used as well). The inner member  232  comprises a thin-walled, non-elastic flexible material such as polyethylene or polyurethane. The inner member  232  may be coated with an antibiotic surface, such as a silver coating, to reduce bacterial growth. The inner member  232  is attached to the outer support member  231  at the orad end portion  233  and the aborad end portion  234  of the supplemental pyloric valve  230  (for example, by welding) to provide an isolated conduit through which material may pass. The orad end portion  233  of the support member  231  is sutured on to the inner wall  207  of the duodenum adjacent the pylorus  205 . The aborad end portion  234  of the outer support member  231  is sutured to duodenum  206  downstream of the orad end portion as shown in  FIG. 3A . The inner member  232  defines a conduit through which material pass from the pylorus  205  into the small intestine  206 . The inflatable member sections  236   a - b  are located between the outer support member  231  and the inner member  232  with the inner member  232  floating relatively loosely within the outer support member  231  so as to permit the inflatable member sections  236   a - b  to expand and contract. 
   The supplemental pyloric valve  230  is implanted to supplement the pylorus of the stomach by further controlling the exit of material from the stomach through the pylorus and into the duodenum. In one embodiment this is done to retain food in the stomach for a greater duration to treat obesity and/or dumping syndrome. The inflatable member sections  236   a - b  and the inner member  232  form a valve  238 . The inflatable members  236   a - b  are attached to the inside of the outer support member  231  between the outer support member  231  and the inner member  232  along the length of the prosthesis  230 . According to this embodiment, the inflatable member section  236   a  forms an orad inflatable member pair and the inflatable member section  236   b  forms an aborad inflatable member pair. Each pair of inflatable members converges together when inflated, to close the valve  238 . The valve  238  is actuated by inflating sections  236   a - b , which causes the inner member  232  to squeeze together to seal the conduit closed. 
   Each section  236   a - b  is coupled to and is fluid communication with a corresponding respective one of conduits  239   a ,  239   b . Conduits  239   a ,  239   b  extend out of the duodenum and are coupled to the pump  241 . Conduits  239   a ,  239   b  are used to selectively deliver inflation medium to and from sections  236   a - b  by an implanted pump and control controller similar to the pump system  40  and electronics unit  50  described above with reference to  FIGS. 1A-1J  and  FIGS. 4-6F . 
   While the invention has been described with reference to particular embodiments, it will be understood to one skilled in the art that variations and modifications may be made in form and detail without departing from the spirit and scope of the invention. 
   For example, the invention may be practiced replacing or augmenting all or part of a portion of the digestive tract such as the bowel or small intestine as described, for example in U.S. application entitled “IMPLANTABLE DIGESTIVE TRACT ORGAN” filed on even date herewith, incorporated herein by reference.