Abstract:
An implant for placement within a hollow body organ, the implant includes a distension device having an undeployed shape for delivery within a hollow body and one or more deployed shapes for implantation therein. The device has sufficient rigidity in its deployed shape to exert an outward force against an interior of the hollow body so as to bring together two substantially opposing surfaces of the hollow body. The implant further includes an implantable pump in fluid communication with the distension device and having a plurality of actuators configured to change the shape of the distension device upon the application of energy thereto such that sequential activation of the plurality of actuators is effective to create pumping action to move fluid through the pump.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to implantable medical devices, and in particular implantable gastric distension devices. 
       BACKGROUND OF THE INVENTION 
       [0002]    Obesity is becoming a growing concern, particularly in the United States, as the number of obese people continues to increase, and more is learned about the negative health effects of obesity. Morbid obesity, in which a person is 100 pounds or more over ideal body weight, in particular poses significant risks for severe health problems. Accordingly, a great deal of attention is being focused on treating obese patients. One proposed method of treating morbid obesity has been to place a distension device, such as a, spring loaded coil inside the stomach. Examples of satiation and satiety inducing gastric implants, optimal design features, as well as methods for installing and removing them are described in commonly owned and pending U.S. patent application Ser. No. 11/469,564, filed Sep. 1, 2006, and pending U.S. patent application Ser. No. 11/469,562, filed Sep. 1, 2006, which are hereby incorporated herein by reference in their entirety. One effect of the coil is to more rapidly induce feelings of satiation defined herein as achieving a level of fullness during a meal that helps regulate the amount of food consumed. Another effect of the coil is to prolong the effect of satiety which is defined herein as delaying the onset of hunger after a meal which in turn regulates the frequency of eating. By way of a non-limiting list of examples, positive impacts on satiation and satiety may be achieved by an intragastric coil through one or more of the following mechanisms: reduction of stomach capacity, rapid engagement of stretch receptors, alterations in gastric motility, pressure induced alteration in gut hormone levels, and alterations to the flow of food either into or out of the stomach. 
         [0003]    With each of the above-described food distension devices, safe, effective treatment requires that the device be regularly monitored and adjusted to vary the degree of distension applied to the stomach. 
         [0004]    During these gastric coil adjustments, it may be difficult to determine how the adjustment is proceeding, and whether the adjustment will have the intended effect. In an attempt to determine the efficacy of an adjustment, some physicians may utilize fluoroscopy with a Barium swallow as the adjustment is being performed. However, fluoroscopy is both expensive and undesirable due to the radiation doses incurred by both the physician and patient. A, a physician may simply adopt a “try as you go” method based upon their prior experience, and the results of an adjustment may not be discovered until hours or days later, when the patient experiences too much distension to the stomach cavity, or the coil induces erosion of the stomach tissue due to excessive interface pressures against the coil. 
         [0005]    Furthermore, the implantable pumps known in the art, such as centrifugal or positive displacement pumps, have high power requirements during operation. The power requirements of such pumps limit their usage for frequent adjustments to fluid levels in the coil. Current pumps also require large housings to encase the mechanical pumping mechanism, gears, and motors, further limiting their usefulness as implantable pumps. Additional components, such as valves, are also necessary to maintain fluid pressure in the coil when power is not supplied to conventional pumps. An example of an implantable pump system is described in US Patent Publication No. 2005/0277974, entitled “Thermodynamically driven reversible infuser pump for use as a remotely controlled gastric band” which was filed on May 28, 2004. 
         [0006]    Accordingly, methods and devices are provided for use with an gastric distension device, and in particular methods and devices are provided which allow adjustment of an gastric distension device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0008]      FIG. 1A  is a schematic diagram of an embodiment of a stomach distension system; 
           [0009]      FIG. 1B  is a perspective view of an embodiment of an implantable portion of the stomach distension system of  FIG. 1A ; 
           [0010]      FIG. 2A  is a perspective view of the stomach distension device of  FIG. 1A ; 
           [0011]      FIG. 2B  is a schematic diagram of the stomach distension device of  FIG. 2A  applied about the gastro-esophageal junction of a patient; 
           [0012]      FIG. 3  is a perspective view of an embodiment of the injection port housing of  FIG. 1A ; 
           [0013]      FIG. 4  is a perspective view of an embodiment of the sensor housing of  FIG. 1A ; 
           [0014]      FIG. 5  is a perspective view of an implantable portion of the stomach distension system according to one embodiment of the invention. 
           [0015]      FIG. 6A  is a perspective view of one exemplary embodiment of a pump having multiple actuators disposed around a flexible tube; 
           [0016]      FIG. 6B  is a perspective view of the pump of  FIG. 6A  with the first actuator activated; 
           [0017]      FIG. 6C  is a perspective view of the pump of  FIG. 6A  with the first and second actuators activated; 
           [0018]      FIG. 6D  is a perspective view of the pump of  FIG. 6A  with the first actuator deactivated and the second actuator activated; 
           [0019]      FIG. 6E  is a perspective view of the pump of  FIG. 6A  with the second and third actuators activated; 
           [0020]      FIG. 6F  is a perspective view of the pump of  FIG. 6A  with the second actuator deactivated and the third actuator activated; 
           [0021]      FIG. 6G  is a perspective view of the pump of  FIG. 6A  with the third and fourth actuators activated; 
           [0022]      FIG. 7  is a perspective view of one exemplary embodiment of a pump having multiple actuators disposed around a flexible tube including a reaction surface; 
           [0023]      FIG. 8  is a perspective view of one exemplary embodiment of a pump having multiple actuators disposed within a tubular member; 
           [0024]      FIG. 9  is a perspective view of one exemplary embodiment of a pump having actuators disposed both around and within a flexible tubular member. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. 
         [0026]    The present invention generally provides systems and methods for forming a distension in a patient. In one exemplary embodiment, a distension system includes an implantable distension device and an implantable pump in fluid communication with the distension device. Optionally, an implantable port can be in fluid communication with the implantable distension device and the pump. The implantable distension device is adjustable and configured to form a distension in a patient, and the implantable port, if present, is configured to receive fluid from a fluid source external to the patient. Exemplary non-limiting examples of adjustable implantable distension devices (e.g., satiation and satiety inducing gastric implants), optimal design features, as well as methods for installing and removing them are described in commonly owned and pending U.S. patent application Ser. No. [ ], filed on even date herewith and entitled “Devices and Methods for Adjusting a Satiation and Satiety-Inducing Implanted Device” [Atty. Docket No. END6514USNP], which is hereby incorporated herein by reference in its entirety. The implantable pump has a plurality of actuators configured to change shape upon the application of energy thereto such that sequential activation of the plurality of actuators is effective to create pumping action to move fluid through the pump. Fluid in the distension system can move in a direction from the pump to the distension device or in a direction from the distension device to the pump. In one embodiment, the pump can be in fluid communication with the implantable port. The system can also include an implantable sensor in communication with the distension device and configured to measure at least a pressure within the distension device. The distension system can optionally include a fluid reservoir in fluid communication with the pump. The fluid reservoir is configured to hold fluid and can be configured to hold in the range of approximately 0.1 to 20 ml of fluid. 
         [0027]    The implantable pump and its plurality of actuators can be arranged in a variety of configurations. In one exemplary embodiment the pump includes a first member having a passageway formed therethrough and being in communication with the plurality of actuators. The actuators can be disposed within the first member or outside the first member. At least one actuator can be configured to expand or contract (e.g., radially or axially) upon the application of energy thereto, and each of the actuators can be configured to move sequentially or independently. In one embodiment, at least one of the actuators can serve as a valve that is able to selectively control the passage of fluid by permitting, preventing, or limiting the passage of fluid. In one exemplary embodiment each actuator comprises an electroactive polymer. 
         [0028]    The pump can be manually activated to move fluid either toward or away from the distension device. Alternatively, the pump can be automatically activated, such as by techniques including timer control, or programmed to be activated in response to certain sensed parameters. 
         [0029]    In one embodiment, the implantable pump effects a pressure change within the distension device in accordance with a programmed schedule. 
         [0030]    Further disclosed herein are methods for adjusting pressure in an implantable distension device. In one embodiment, the method can include sensing a clinically relevant parameter, adjusting a pressure within the distension device in response to the sensed clinically relevant parameter by activating a pump in fluid communication with the distension device. In one embodiment, the pump can be formed of a plurality of actuators configured to change shape upon the application of energy thereto such that sequential activation of the plurality of actuators is effective to create pumping action to move fluid through the pump. The sensing of the clinically relevant parameter can be effected using an implantable sensor. The clinically relevant parameter can be a pressure, in which case, the implantable sensor is a pressure sensor. In such an embodiment, the sensed pressure is compared to a desired pressure range and the pressure within the distension device is adjusted to be approximately within the desired pressure range if the sensed pressure is not within a desired pressure range. In one embodiment, the pump can be automatically activated, although other activation techniques, including manual activation, are also envisioned. 
         [0031]    Also disclosed herein is a pumping device including a fluid conduit member having a passageway formed therethrough, and a plurality of orientation-changing actuators disposed within the fluid conduit member. Each actuator is independently configurable between a normal, relaxed state in which the actuator occludes a portion of the passageway of the fluid conduit member and an energized configuration in which fluid flow is permitted between an outer surface of the actuator and an inner surface of the fluid conduit member. The actuators are also configured to change orientation upon the application of energy thereto such that sequential activation of the plurality of actuators is effective to create pumping action to move fluid through the first member. 
         [0032]    The actuators can be formed from a variety of materials. In one exemplary embodiment, each actuator comprises an electroactive polymer (EAP). For example, each actuator can include a least one electroactive polymer composite having at least one flexible conductive layer, an electroactive polymer layer, and an ionic gel layer. Each actuator can also include a return electrode and a delivery electrode coupled thereto, the delivery electrode being adapted to deliver energy from an energy source. The actuators can be configured to move independently or sequentially. 
         [0033]    The present invention generally provides systems and methods for forming a distension in a patient. In general, the systems and methods allow the pressure or volume of fluid in a distension device to be adjusted. The pressure or volume adjustment is effected by the use of an implantable pump. The implantable pump allows the pressure or volume of fluid in a distension device to be adjusted without the need for fluid to be added from an external source. 
         [0034]    While the present invention can be used with a variety of distension systems known in the art,  FIG. 1A  illustrates one exemplary embodiment of a stomach distension system  10  in use in a patient. As shown, the system  10  generally includes an implantable portion  10   a  and an external portion  10   b .  FIG. 1B  illustrates the implantable portion  10   a  outside of a patient. The implantable portion  10   a  includes an adjustable gastric coil  20  that is configured to be positioned around the upper portion of a patient&#39;s stomach  40 , and an injection port housing  30  that is fluidly coupled to the adjustable gastric coil  20 , e.g., via a catheter  50 . 
         [0035]    The injection port housing  30  is adapted to allow fluid to be introduced into and removed from the gastric coil  20  to thereby adjust the size of the coil, and thus the pressure applied to the stomach. The injection port housing  30  can thus be implanted at a location within the body that is accessible through the tissue. Typically, injection ports may be positioned on the coil or attached to a layer of the stomach 
         [0036]    The internal portion  10   a  can also include a sensing or measuring device in fluid communication with the closed fluid circuit in the implantable portion  10   a  such that the measuring device can take measurements related to any parameter relevant to implantable distension devices. Such clinically relevant parameters include, but are not limited to, temperature, pressure, changes in pressure, acoustic input, tissue impedance, changes in sensed tissue impedance, chemical composition, changes in chemical composition, pulse count, pulse width and amplitude. While the methods and devices discussed herein can relate to any sensed data parameter, in an exemplary embodiment, the measurements relate to pressure, and the methods and devices disclosed herein will be discussed in the context of measuring the fluid pressure of the closed fluid circuit. While the measuring device can have various configurations and it can be positioned anywhere along the internal portion  10   a , including within the injection port housing  30 , in the illustrated embodiment the measuring device is in the form of a pressure sensor that is disposed within a sensor housing  60  positioned adjacent to the injection port housing  30 . The catheter  50  can include a first portion that is coupled between the gastric coil  20  and the sensor housing  60 , and a second portion that is coupled between the sensor housing  60  and the injection port housing  30 . 
         [0037]    In addition to sensing pressure of fluid within the internal portion  10   a , pressure of fluid within the esophagus and/or the stomach  40  can also be sensed using any suitable device, such as an endoscopic manometer. By way of non-limiting example, such fluid pressure measurements can be compared against measured pressure of fluid within the internal portion  10   a  before, during, and/or after adjustment of pressure within the internal portion  10   a . Other suitable uses for measured pressure within the esophagus and/or the stomach  40  will be appreciated by those skilled in the art. 
         [0038]    As further shown in  FIG. 1A , the external portion  10   b  generally includes a pressure reading device  70  that is configured to be positioned on the skin surface above the sensor housing  60  (which can be implanted beneath thick tissue, e.g., over 10 cm thick) to non-invasively communicate with the sensor housing  60  and thereby obtain pressure measurements. The pressure reading device  70  can optionally be electrically coupled (in this embodiment via an electrical cable assembly  80 ) to a control box  90  that can display the pressure measurements, or other data obtained from the pressure reading device  70 . 
         [0039]      FIG. 1B  shows the implantable portion  10   a  in more detail. In the illustrated embodiment, the implantable portion  10   a  includes an adjustable gastric coil  20 , an injection port housing  30  that is fluidly coupled to the adjustable gastric coil  20 , a sensor housing  60 , and a pump  110 . The pump  110  can have a variety of configurations which will be discussed in more detail below. In the embodiment shown in  FIG. 1B , the pump  110  generally includes an elongate member  112 . 
         [0040]      FIG. 2A  shows the gastric coil  20  in more detail. While the gastric coil  20  can have a variety of configurations, and various gastric coils currently known in the art can be used with the present disclosure, in the illustrated embodiment the gastric coil  20  has a generally elongate shape with a support structure  22  having first and second opposite ends  20   a ,  20   b  that can be formed in a C-shape. Various techniques can be used to keep the ends  20   a ,  20   b  in relative proximity to one another. In the illustrated embodiment, the fluid bladder pressure may be varied to control the proximity of the ends relative to each other. The gastric coil  20  can also include a variable volume member, such as an inflatable balloon  24 , that is disposed or formed on one side of the support structure  22  and that is configured to be positioned adjacent to tissue. The balloon  24  can expand or contract against the outer wall of the coil to form an adjustable size coil for controllably restricting food intake into the stomach. 
         [0041]    A person skilled in the art will appreciate that the gastric coil can have a variety of other configurations. Moreover, the various methods and devices disclosed herein have equal applicability to other types of implantable coils. 
         [0042]      FIG. 2B  shows the adjustable gastric coil  20  applied the stomach of a patient. As shown, the coil  20  at least substantially distends the stomach  40 . After the coil  20  is implanted, it may be deployed. A person skilled in the art will appreciate that various techniques, including mechanical and electrical techniques, can be used to adjust the coil. 
         [0043]    The fluid injection port housing  30  can also have a variety of configurations. In the embodiment shown in  FIG. 3 , the injection port housing  30  has a generally cylindrical shape with a distal or bottom surface and a perimeter wall extending proximally from the bottom surface and defining a proximal opening  32 . The proximal opening  32  can include a needle-penetrable septum  34  extending there across and providing access to a fluid reservoir (not visible in  FIG. 3 ) formed within the housing. The septum  34  is preferably placed in a proximal enough position such that the depth of the reservoir is sufficient enough to expose the open tip of a needle, such as an endoscopic Huber-like needle, so that fluid transfer can take place. The septum  34  is preferably arranged so that it will self seal after being punctured by a needle and the needle is withdrawn. As further shown in  FIG. 3 , the housing  30  can further include a catheter tube connection member  36  that is in fluid communication with the reservoir and that is configured to couple to a catheter (e.g., the catheter  50 ). A person skilled in the art will appreciate that the housing can be made from any number of materials, including stainless steel, titanium, or polymeric materials, and the septum  34  can likewise be made from any number of materials, including silicone. 
         [0044]    As indicated above, the system  10  can also include a pressure measuring device in communication with the closed fluid circuit and configured to measure pressure (e.g., fluid pressure) which corresponds to the amount of distension applied by the adjustable gastric coil  20  to the patient&#39;s stomach  40 . Measuring the pressure enables a person (e.g., a physician, a nurse, a patient, etc.) to evaluate the efficacy and functionality of the distension created by a coil adjustment. In the illustrated embodiment, as shown in  FIG. 4 , the pressure measuring device is in the form of a pressure sensor  62  disposed within the sensor housing  60 . The pressure measuring device can, however, be disposed anywhere within the closed hydraulic circuit of the implantable portion. 
         [0045]    In general, the illustrated sensor housing  60  includes an inlet  60   a  and an outlet  60   b  that are in fluid communication with the fluid in the implantable portion  10   a . An already-implanted catheter  50  can be retrofitted with the sensor housing  60 , such as by severing the catheter  50  and inserting barbed connectors (or any other connectors, such as clamps, clips, adhesives, welding, etc.) into the severed ends of the catheter  50 . The sensor  62  can be disposed within the housing  60  and be configured to respond to fluid pressure changes within the hydraulic circuit and convert the pressure changes into a usable form of data. The pressure sensor  62  disposed within the housing  60  can sense and monitor the adjusted state of the coil statically or while fluid is being pumped. 
         [0046]    While not shown, the pressure sensing system can also include a microcontroller, a TET/telemetry coil, and a capacitor. Optionally, the pressure sensing system can further comprise a temperature sensor (not shown). The microcontroller, TET/telemetry coil, and capacitor can be in communication via a circuit board (not shown) or any via any other suitable component(s). It will also be appreciated that TET/telemetry coil and capacitor may collectively form a tuned tank circuit for receiving power from external portion, and transmitting the pressure measurement to the pressure reading device. 
         [0047]    Various pressure sensors known in the art can be used, such as a wireless pressure sensor provided by CardioMEMS, Inc. of Atlanta, Ga., though a suitable MEMS pressure sensor may be obtained from any other source, including but not limited to Integrated Sensing Systems (ISSYS), and Remon Medical. One exemplary MEMS pressure sensor is described in U.S. Pat. No. 6,855,115, the disclosure of which is incorporated by reference herein for illustrative purposes only. It will also be appreciated that suitable pressure sensors may include, but are not limited to, capacitive, piezoresistive, silicon strain gauge, or ultrasonic (acoustic) pressure sensors, as well as various other devices capable of measuring pressure. Additionally an angle measurement may be used where the angle between any of the individual links is measured with a one of the above mentioned methods. 
         [0048]    The pressure reading device  70  can also have a variety of configurations, and one exemplary pressure reading device is disclosed in more detail in commonly-owned U.S. Patent Application Publication No. 2006/0189888 and U.S. Patent Application Publication No. 2006/0199997, each of which is hereby incorporated by reference in its entirety. In general, the pressure reading device  70  can non-invasively measure the pressure of the fluid within implanted portion even when the injection port housing  30  or sensor housing  60  is implanted beneath thick (at least over 10 centimeters) subcutaneous fat tissue. The physician may hold pressure-reading device  70  against the patient&#39;s skin near the location of sensor and observe the pressure reading on a display on the control box  90 . The pressure reading device  70  can also be removably attached to the patient, such as during a prolonged examination, using straps, adhesives, and other well-known methods. The pressure reading device  70  can operate through conventional cloth or paper surgical drapes, and can also include a disposable cover (not shown) that may be replaced for each patient. 
         [0049]      FIG. 5  illustrates one embodiment of the proximal end of the implantable portion  10   a  ( FIGS. 1A and 1B ) of the implantable distension system  10 . As shown, the proximal end of the implantable portion  10   a  includes an injection port housing  30 , which is in fluid communication with a reservoir  105  and a pump  110 . The proximal end may also include a sensor housing  60 , as well as one or more sensor/power leads  101 . Conduit  50   a  provides fluid communication between the individual components of the proximal end of the implantable portion  10   a . Catheter  50  provides fluid communication between the proximal end of the implantable portion  10   a  shown in  FIG. 5  and downstream distension device  20  ( FIG. 1B ). Although the components shown in  FIG. 5  are shown in an inline configuration, one skilled in the art will appreciate that the components can be connected in any order and in any configuration, i.e., in a T configuration or a Y configuration, for example. 
         [0050]    As shown in  FIG. 5 , the injection port housing  30 , if present, can optionally include an anchoring device, such as hooks  35 , that can be used to anchor the injection port housing  30  within the patient&#39;s body, preferably to the inner surface of the stomach. Although  FIG. 5  shows that the housing  30  is arranged in line with the reservoir  105 , the pump  110  and the sensor housing  60 , the housing  30  can be connected to the other components and conduit  50   a  in other ways, i.e., in a T configuration or a Y configuration, for example. The injection port housing  30  itself is optional because the implantable distension system  10   a  ( FIG. 1B ) can be filled with fluid prior to implantation or at the time of implantation. The pressure in the downstream distension device  20  ( FIG. 1B ) can then be adjusted using the pump  110  to move fluid into or out of the distension device  20 . 
         [0051]    Reservoir  105  provides an optional means for holding an additional supply of fluid. For example, the reservoir  105  can contain 0.1-20 ml of fluid. As shown, the reservoir  105  can be a portion of conduit  50   a  with a larger diameter than the nominal diameter of the conduit  50   a . Various other configurations can be used to provide a reservoir  105 , such as separate reservoir components connected to, and in fluid communication with, the conduit  50   a  or any other components, i.e., the injection port housing  30 , the pump  110  or the sensor housing  60 . Although  FIG. 5  shows that the reservoir  105  is arranged in line between the pump  110  and the injection port housing  60 , one skilled in the art will appreciate that the reservoir  105  can be connected to the other components and conduit  50   a  in other ways, i.e., in a T configuration or a Y configuration, for example. It will also be appreciated that the reservoir  105  need not necessarily contain enough fluid to fill and empty the entire coil  20  ( FIGS. 1A and 1B ). For example, during the first fills of the coil  20 , fluid may be delivered via an injection through the injection port housing  30 . During this time the pump  110  can be retained in an open position. Alternatively, the reservoir  105  can be filled and then the fluid can be delivered to the coil  20  by the pump  110 . Once the coil  20  is at functional fullness, i.e., occluding the stomach enough to cause a distension of intake, the reservoir  105  can be filled with enough fluid to accommodate future fill and adjustment needs without the need to add additional fluid via an injection port housing  30 . One skilled in the art will appreciate that the reservoir  105  is optional, and in an embodiment without reservoir  105 , not shown, the conduit  50   a  can optionally contain enough fluid to allow adjustments to the amount of fluid in the coil  20 . 
         [0052]    The embodiment shown in  FIG. 5  includes an optional sensor housing  60  that is disposed in fluid communication with the components of the proximal end of the implantable portion  10   a  ( FIG. 1B ). Although  FIG. 5  shows that the sensor housing  60  is arranged inline with the catheter  50  and the conduit  50   a , one skilled in the art will appreciate that the sensor housing  60  can be connected to the other components in other ways, i.e., in a T configuration or a Y configuration, for example. Alternatively, a sensor can be placed in other locations in the system, such as on the coil itself. Sensor/power leads  101  can provide a connection between the sensor housing  60  and the pump  110  to supply energy to the pump, as will be discussed in more detail below. 
         [0053]    The implantable pump  110  functions to move fluid into and out of the coil  20  to increase or decrease pressure within the coil as needed. Although the pump can have a variety of configurations, in one example the pump is based upon electroactive polymer (EAP) technology as discussed in more detail below. The use of EAP technology to form an implantable pump  110  provides a number of advantages, such as small size, low voltage requirements, high power density, and simplicity in terms of the number of moving parts. 
         [0054]      FIG. 6A  illustrates one exemplary embodiment of a pumping mechanism using EAP actuators. As shown, the pump  110  generally includes an elongate member  112  having a proximal end  114 , a distal end  116 , and an inner passageway or lumen  118  extending therethrough between the proximal and distal ends  114 ,  116 . The inner lumen  118  defines a fluid pathway. The elongate member  112  may optionally be formed as a portion of conduit  50   a  ( FIG. 5 ) such that the pump  110  is in fluid communication with catheter  50  and downstream distension device  20 . As shown, the pump  110  can include multiple actuators  122   a ,  122   b ,  122   c ,  122   d ,  122   e  that are disposed around the outer surface  120  of the elongate member  112 . In use, as will be explained in more detail below, the actuators  122   a - 122   e  can be sequentially activated using electrical energy to cause the actuators  122   a - 122   e  to radially contract, thereby contracting the elongate member  112  and forcing fluid to move in one direction therethrough. The actuators can also be configured to axially contract and expand to move fluid through the elongate member  112 . 
         [0055]    In an alternative embodiment, the expansion and contraction of actuators  122   a - 122   e  may be used only to increase or decrease internal pressure within the coil without actually moving fluid. In this embodiment, the pump  110  could be disposed anywhere in fluid communication with the distension system. Upon the application of energy to the one or more of the actuators  122   a - 122   e , the volume of the inner lumen  118  would be changed, effecting a corresponding pressure change in the system  10 . 
         [0056]    The elongate member  112  can have a variety of configurations, but in one exemplary embodiment it is in the form of a flexible elongate tube or cannula that is configured to receive fluid flow therethrough, and that is configured to flex and/or change size in response to orientational changes in the actuators  122   a - 22   e . The shape and size of the elongate member  112 , as well as the materials used to form a flexible and/or elastic elongate member  112 , can vary depending upon the intended use. In certain exemplary embodiments, the elongate member  112  can be formed from a biocompatible polymer, such as silicone or latex. Other suitable biocompatible elastomers include, by way of non-limiting example, synthetic polyisoprene, chloroprene, fluoroelastomer, nitrile, and fluorosilicone. A person skilled in the art will appreciate that the materials can be selected to obtain the desired mechanical properties. While not shown, the elongate member  112  can also include other features to facilitate attachment thereof to a medical device, a fluid source, etc. 
         [0057]    The actuators  122   a - 122   e  can also have a variety of configurations. In the illustrated embodiment, the actuators  122   a - 122   e  are formed into an annular member from an EAP laminate or composite that is rolled around an outer surface  120  of the elongate member  112 . An adhesive or other mating technique can be used to attach the actuators  122   a - 122   e  to the elongate member  112 . The actuators  122   a - 122   e  are preferably spaced a distance apart from one another to allow the actuators  122   a - 122   e  to radially contract and axially expand when energy is delivered thereto, however they can be positioned in contact with one another. A person skilled in the art will appreciate that actuators  122   a - 122   e  can alternatively be disposed within the elongate member  112 , or they can be integrally formed with the elongate member  112 . The actuators  122   a - 122   e  can also be coupled to one another to form an elongate tubular member, thereby eliminating the need for the flexible member  112 . A person skilled in the art will also appreciate that, while five actuators  122   a - 122   e  are shown, the pump  110  can include any number of actuators (e.g., ranging from two to more than five). For example, the number and position of the actuators can be varied to control the flow and/or pressure characteristics of the pump and the pumping action. The actuators  122   a - 122   e  can also have a variety of configurations, shapes, and sizes to alter the pumping action of the device. 
         [0058]    As shown, the actuators  122   a - 122   e  can be coupled to the flexible elongate member  112  in a variety of orientations to achieve a desired fluid movement. In an exemplary embodiment, the orientation of the actuators  122   a - 122   e  is arranged such that the actuators  122   a - 122   e  will radially contract and axially expand upon the application of energy thereto. In particular, when energy is delivered to the actuators  122   a - 122   e , the actuators  122   a - 122   e  can decrease in diameter, thereby decreasing an inner diameter of the elongate member  112 . Such a configuration allows the actuators  122   a - 122   e  to be sequentially activated to pump fluid through the elongate member  112 , as will be discussed in more detail below. A person skilled in the art will appreciate that various techniques can be used to deliver energy to the actuators  122   a - 122   e . For example, each actuator  122   a - 122   e  can be coupled to a return electrode and a delivery electrode that is adapted to communicate energy from a power source to the actuator. The electrodes can extend through the inner lumen  18  of the elongate member  112 , be embedded in the sidewalls of the elongate member  112 , or they can extend along an external surface of the elongate member  112 . The electrodes can couple to a battery or other energy source. Where the pump  110  is adapted to be implanted within the patient, the electrodes can be coupled to a transformer that is adapted to be subcutaneously implanted and that is adapted to store energy and/or receive energy from an external source located outside of the patient&#39;s body. An exemplary configuration is shown in  FIG. 5 , in which the transformer or power source is contained in the sensor housing  60  and sensor/power leads  101  deliver energy to the pump  110 . 
         [0059]    Alternatively, energy can be supplied by an external device (e.g., the reading device  70  shown in  FIG. 1A ) that can transcutaneously deliver energy to the sensor housing  60  ( FIG. 5 ), e.g., when the external device is moved in proximity of the sensor housing  60 . The external device can be mobile (e.g., a wand or hand-held unit that can be waved or otherwise placed in proximity of the sensor housing  60 ) or stationary (e.g., a bedside, desk-mounted, or car-mounted box that the patient can move near). 
         [0060]      FIGS. 6B-6G  illustrate one exemplary method for sequentially activating the actuators  122   a - 122   e  to create a peristaltic-type pumping action. In this exemplary embodiment the pump moves fluid in a distal direction toward coil  FIG. 1B ), which would be located distally of the pump  110 . The sequence can begin by delivering energy to a first actuator  122   a  such that the actuator constricts a portion of the elongate member  112  and reduces the diameter of the inner lumen  118 . While maintaining energy delivery to the first actuator  122   a , energy is next delivered to a second actuator  122   b  adjacent to the first actuator  122   a . The second actuator  122   b  radially contracts, i.e., decreases in diameter, to further compress the elongate member  112 , as illustrated in  FIG. 6C . As a result, fluid within the inner lumen  118  adjacent to actuators  122   a  and  122   b  will be forced in the distal direction toward the distal end  116  of the elongate member  112 . As shown in  FIG. 6D , while maintaining energy delivery to the second actuator  122   b , energy delivery to the first actuator  122   a  can be terminated, thereby causing the first actuator  122   a  to radially expand and return to an original, deactivated configuration. Energy can then be delivered to a third actuator  122   c  adjacent to the second actuator  122   b  to cause the third actuator  122   c  to radially contract, as shown in  FIG. 6E , further pushing fluid through the inner lumen  118  in a distal direction. Energy delivery to the second actuator  122   b  can then be terminated such that the second actuator  122   b  radially expands to return to its original, deactivated configuration, as shown in  FIG. 6F . Energy can then be delivered to a fourth actuator  122   d , as shown in  FIG. 6G , to radially contract the fourth actuator  122   d  and further pump fluid in the distal direction. This process of sequentially activating and de-activating adjacent actuators is continued resulting in a “pulse” which travels from the proximal end  114  of the pump  110  to the distal end  116  of the pump  110 . The process illustrated in  FIGS. 6B-6G  can be repeated, as necessary, to continue the pumping action. For example, energy can be again delivered to actuators  122   a - 122   e  to create a second pulse. One skilled in the art will appreciate that the second pulse can follow directly behind the first pulse by activating the first actuator  122   a  at the same time as the last actuator  122   d , or alternatively the second pulse can follow the first pulse some time later. One skilled in the art will further appreciate that the sequence described above can be reversed to effect flow in a proximal direction, i.e., away from the coil. 
         [0061]    The pump  110  can also include one or more actuators configured to form a valve. By forming a valve using one or more of the actuators, the pressure and volume of fluid in the coil  20  ( FIG. 1B ) can be maintained without the need for additional components. In one embodiment, not shown, at least one of the actuators  122   a - 122   e  is adapted to form a valve by constricting a portion of the elongate member  112  to an extent sufficient to prevent fluid flow through the inner lumen  118 . In this embodiment the elongate member  112  is constricted by one or more of the actuators  122   a - 122   e  until the inner walls of the elongate member  112  are in contact (or close proximity) with each other, preventing fluid flow through the compressed segment and thus serving as a valve.  FIGS. 7-9  show various other embodiments in which the actuators can form a valve. 
         [0062]    In the embodiment shown in  FIG. 7 , the pump  210  includes a plurality of actuators  222   a - 222   e , which are formed around elongate member  212 , and a reaction surface  225 , which can be formed from a non-compressible material, disposed within the elongate member  212 . In a contracted state, actuators  222   a - 222   e  compress the elongate member  212  against the reaction surface  225 , thereby sealing the inner lumen and forming a valve. Similar to the actuators discussed above with respect to  FIGS. 6B-6G , the actuators  222   a - 222   e  are in a non-compressed state in their relaxed or natural configuration, thus allowing a portion of the lumen within the elongate member  212  to remain open. The actuators  222   a - 222   e  contract when energy is delivered thereto. Using the same method described above, the actuators can be sequentially activated to create a peristaltic-type pumping action. When energy is delivered to one or more of the actuators, e.g., actuator  222   b  as shown in  FIG. 7 , the actuator will compress the elongate member  212  against the reaction surface  225  thereby preventing fluid flow through the compressed segment and thus serving as a valve. One skilled in the art will appreciate that the actuators can alternatively be configured such that in their relaxed state the actuators are closed and compress the elongate member  212  against the reaction surface  225 . Upon the delivery of energy to such actuators, the actuators will expand and allow fluid to pass through the affected segments of the lumen  218 . One skilled in the art will further appreciate that the sequence of activating the actuators can be controlled to effect flow in a proximal direction, i.e., away from the coil, or in a distal direction, i.e., towards the coil. 
         [0063]    In another embodiment, shown in  FIG. 8 , the pump  310  includes actuators  322   a - 322   e  that are disposed entirely within elongate member  312 . In this embodiment, the actuators  322   a - 322   e  can be in the form of solid members that can be of a variety of shapes, including a disk-like shape as shown. Further, the actuators are configured to radially expand or contract when energy is delivered thereto. For example, as shown in  FIG. 8 , the actuators can be in an expanded form in their relaxed state. In such a relaxed state the actuators occlude the lumen  318  within the elongate member  312  and prevent passage of fluid through the affected segment of the lumen. However, when energy is applied, such as to actuator  322   d  in  FIG. 8 , the actuator compresses to allow fluid to flow between an outer surface of actuator  322   d  and an adjacent inner surface of elongate member  312 . Thus, fluid can flow past the actuators  322   a - 322   e  in their contracted state, but the actuators  322   a - 322   e  form a valve that prevents fluid flow when they are in their expanded state. A peristaltic-type pumping action can also be created by sequentially activating and deactivating the actuators  322   a - 322   e  in the manner discussed above. One skilled in the art will also appreciate that the pump of  FIG. 8  can be alternatively configured such that the actuators are in a compressed configuration when in their natural state, thus allowing fluid flow, and in an expanded configuration when energy is applied thereto. One skilled in the art will further appreciate that the sequence of activating the actuators can be controlled to effect flow in a proximal direction, i.e., away from the coil, or in a distal direction, i.e., towards the coil. 
         [0064]    In yet another embodiment, shown in  FIG. 9 , the pump  410  can include both internal and external actuators. As shown, the pump  410  includes substantially solid actuators  430 ,  440  contained entirely inside the elongate member  412 , and annular actuators  422   a - 422   e  formed on the outer surface of the elongate member  412 . Any number of internal and external actuators  422   a - 422   e ,  430 ,  440  may be provided, and the actuators can be formed in any configuration. For example, the external actuators  422   a - 422   e  can be located between a pair of internal actuators  430 ,  440 , which may form terminal ends of the pump. In this configuration, the internal actuators  430 ,  440  can operate as valves as described in detail above. For example, one of the internal actuators, e.g., actuator  430  as shown in  FIG. 9 , can be in an expanded form in its relaxed state to seal the inner lumen of the elongate member  412  at one terminal end of the pump. Using methods similar to those described above, the actuators can be sequentially activated to create a peristaltic-type pumping action. For example, in the configuration shown in  FIG. 9 , the external actuators  422   a - 422   e  can be sequentially activated and de-activated, as described above, resulting in a fluid “pulse” that travels through the inner lumen  418  of the elongate member  412 . The sequential activation of the external actuators can be repeated, as necessary, to continue the pumping action. One skilled in the art will appreciate that other arrangements and configurations of internal and external actuators are possible. For example, an internal actuator  430 ,  440  may be located between each pair of external actuators  422   a - 422   e . In addition, one skilled in the art will appreciate that the sequence of activating the actuators can be controlled to effect flow in a proximal direction, i.e., away from the coil, or in a distal direction, i.e., towards the coil. 
         [0065]    One skilled in the art will appreciate that while the actuators are discussed in terms of an ability to contract and expand radially, they can alternatively be configured to contract and expand axially. 
         [0066]    As discussed above, a fluid reservoir need not be present in the system. Instead, the elongate member  112 ,  212 ,  312 ,  412  shown in  FIGS. 6A-9  could also serve as means for holding an additional supply of fluid. For example, the upstream (proximal) side of the elongate member  112 ,  212 ,  312 ,  412  can be oversized and filled with an additional volume of fluid to meet the operational needs of the system. Activation of one or more of the actuators, as discussed above, can cause fluid to move either toward or away from a coil, which would be disposed distally of the pump. One skilled in the art will appreciate that, in the embodiment discussed above in which the expansion and contraction of actuators is used to increase or decrease internal pressure within the coil without actually moving fluid, an additional volume of fluid is not needed to effect a pressure change in the system  10 . 
         [0067]    Additional information on EAP pump technology is also disclosed in commonly-owned U.S. Patent Application Publication No. 2007/0025868 A1, entitled “Electroactive Polymer-Based Pump,” filed on Jul. 28, 2005, which is hereby incorporated by reference in its entirety. 
         [0068]    The present invention also provides a method of adjusting pressure in an implantable distension device system  10 . In one embodiment, the method can include sensing a clinically relevant parameter and adjusting a pressure within the distension device in response to the sensed clinically relevant parameter by activating a pump in fluid communication with the distension device  20 . The EAP-based pump can be the type described with respect to  FIGS. 6A-9 . That is, the pump can be formed of a plurality of actuators configured to change shape upon the application of energy thereto such that sequential activation of the plurality of actuators is effective to create pumping action to move fluid through the pump. The clinically relevant parameter can be sensed using an implantable sensor. 
         [0069]    In one embodiment, the sensed clinically relevant parameter is a pressure, although it is understood that it can include any one of the other parameters identified above, as well as other clinically relevant parameters. In this embodiment, the pressure can be sensed using an implantable pressure sensor  62 , as discussed above. The method can include sensing a pressure in an implanted distension device  10   a , comparing the sensed pressure to a desired pressure (including a desired pressure range), and adjusting the pressure within the distension device  10   a  to be approximately equal to the desired pressure (or desired pressure range) if the sensed pressure is not equal to the desired pressure (or desired pressure range) by activating a pump in fluid communication with the distension device  20  to achieve a desired pressure (or desired pressure range) in the distension device. 
         [0070]    In one embodiment, activation of the pump  110  could automatically occur if the sensed clinically relevant parameter (e.g., pressure, etc.) in the coil  20  were higher than a desired value or range, in which case fluid could be pumped out of the coil  20  to reduce the pressure. Conversely, if the sensed parameter in the coil  20  were lower than a desired value or range, the fluid could be pumped into the coil (e.g., from a reservoir or from an implanted catheter) until a desired target for the parameter is achieved. It is understood that depending on what is being sensed, and where it is being sensed, the decision to pump fluid into or out of the coil bladder in response to a give level of the clinically relevant parameter may be reversed. In yet another configuration, if a sensed clinically relevant parameter (e.g., absolute pressure at a given duration, pressure gradient, etc.) in the coil  20  which correlates with undesirable eating habits was measured, the fluid could be pumped into the coil (e.g., from a reservoir or from an implanted catheter) until a sufficient distension was created. This distension would provide feedback to the patient (which can be immediate or delayed) to stop eating by inducing a physiologic response (e.g., vomiting, etc.). The distension would be sustained in place until a triggering event (e.g., elapsed time) occurred to return the system to a normal operating state. For safety purposes, an override which can be activated by the patient or other caregiver may be provided. This override may be activated through a function in the external portion  10   b  of the stomach distension system  10 . Other techniques for automatic actuation can be used such as timer control, or the system can be programmed to activate the pump in response to certain sensed parameters or events, or according to a programmed schedule. For example, the implantable pump can effect a pressure increase within the distension device (i.e., move fluid towards the distension device) when a patient is determined to be eating, or when the patient is awake (or during selected hours of a day) and effect a pressure decrease within the distension device (i.e., move fluid away from the distension device) when the patient is asleep (or during other selected hours of a day). Those skilled in the art will appreciate that the programmed schedule can be based on a multitude of factors including type of day (e.g., holidays, weekday, weekend), anticipated patient activities, and the like. Those skilled in the art will appreciate that the pressure in the coil  20  can be controlled using closed-loop methods such as PID (proportional-integral-derivative) control schemes or other appropriate methods including digital control schemes. 
         [0071]    One skilled in the art will appreciate that certain safety features may be built into the pump design to provide contingencies in the event of a malfunction or a loss of power. By way of example, if a power outage (or malfunction) is detected, or if the remaining power falls below a predetermined threshold, the system can be configured to default to a relaxed state in which the distension is relaxed and/or opened until the power level is restored or the malfunction corrected. 
         [0072]    An alternative pump may be similar to implantable insulin pumps that are commonly used. Displacement of the piston draws the fluid from a reservoir into a piston chamber; when the piston returns to its original position, it forces the fluid through a free floating catheter, which is inserted into the coils bladder. The fluid pump uses freon gas to produce positive pressure, which pushes the fluid from a reservoir into a valve-type accumulator and into the catheter. The reservoirs in would be refillable. A hypodermic needle, inserted directly through the patient&#39;s skin into the pump&#39;s reservoir, removes any unused fluid and replaces it with a fresh supply. The Hypodermic needle may also access the pumps reservoir in a Trans oral if the reservoir is inside the stomach. 
         [0073]    There is an opportunity to increase the output from the pump by using a hydraulic amplifier or intensifier. This is defined as A fluid device which enables one or more inputs to control a source of fluid power and thus is capable of delivering at its output an enlarged reproduction of the essential characteristics of the input. Hydraulic amplifiers may utilize sliding spools, nozzle-flappers, jet pipes, etc. 
         [0074]    The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of a device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application. 
         [0075]    Preferably, the invention described herein will be processed before surgery. First, a new or used system is obtained and if necessary cleaned. The system can then be sterilized by any known and suitable technique, including ethylene oxide sterilization. In one sterilization technique, the system is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and system are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the system and in the container. The sterilized system can then be stored in the sterile container. The sealed container keeps the system sterile until it is opened in the medical facility. 
         [0076]    It is preferred that device is sterilized. This can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, steam. 
         [0077]    Any patent, publication, application or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. 
         [0078]    One skilled in the art will appreciate further features and advantages of the invention based on the above-described embodiments. Accordingly, the invention is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety.