Patent Publication Number: US-2009228063-A1

Title: System and method of communicating with an implantable antenna

Description:
FIELD 
     The present application relates to methods and devices for aligning an antenna implanted under the skin with an external device. 
     BACKGROUND 
     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 method of treating morbid obesity has been to place a restriction device, such as an elongated band, about the upper portion of the stomach. Gastric bands have typically comprised a fluid-filled elastomeric balloon with fixed endpoints that encircles the stomach just inferior to the esophageal-gastric junction to form a small gastric pouch above the band and a reduced stoma opening in the stomach. When fluid is infused into the balloon, the band expands against the stomach creating a food intake restriction or stoma in the stomach. To decrease this restriction, fluid is removed from the band. The effect of the band is to reduce the available stomach volume and thus the amount of food that can be consumed before becoming “full.” 
     Food restriction devices have also comprised mechanically adjusted bands that similarly encircle the upper portion of the stomach. These bands include any number of resilient materials or gearing devices, as well as drive members, for adjusting the bands. Additionally, gastric bands have been developed that include both hydraulic and mechanical drive elements. It is also known to restrict the available food volume in the stomach cavity by implanting an inflatable elastomeric balloon within the stomach cavity itself. The balloon is filled with a fluid to expand against the stomach walls and, thereby, decrease the available food volume within the stomach. 
     With each of the above-described food restriction devices, safe, effective treatment requires that the device be regularly monitored and adjusted to vary the degree of restriction applied to the stomach. Traditionally, adjusting a gastric band required a scheduled clinician visit during which a Huber needle and syringe were used to penetrate the patient&#39;s skin and remove fluid from the balloon via an injection port. More recently, implantable pumps have been developed which enable non-invasive adjustments of the band. An external programmer communicates with the implanted pump using telemetry to control the pump. During a scheduled visit, a physician places a hand-held portion of the programmer near the gastric implant and transmits command signals to the implant. The implant in turn adjusts the band and transmits a response command to the programmer. 
     Implants such as those described above include electronics, such as an antenna, which are used to transmit information to an external device in order to control adjustment of the band. It is important for the implanted antenna to be properly aligned with the external device to allow for successful information transmissions. It can be difficult and time-consuming to properly align the internal antenna with the external devices as to power the implant and/or transmit data therebetween as the antenna can shift locations and orientations beneath the skin. 
     Thus, there remains a need for a system and method capable of aligning an antenna implanted under the skin with an external device. 
     SUMMARY 
     Various methods and devices for aligning an internal antenna with an external device are provided. In one embodiment, an implantable restriction system is provided and includes an implantable restriction device configured to form a restriction in a pathway, and an implantable housing associated with the implantable restriction device. The housing has at least one antenna that can be configured to communicate telemetrically with a transceiver regardless of a rotational orientation of the housing about an axis. The at least one antenna can extend along an axis aligned with the longitudinal axis of a catheter extending from the housing. The transceiver can have a variety of forms. For example, the transceiver can be an external device located adjacent to a tissue surface, or the transceiver can be disposed on a device that can be configured to be delivered internally within a patient&#39;s body. In one embodiment, the implantable housing can contain a sensor that can be configured, for example, to measure at least one of a system parameter and a physiological parameter, and the antenna can be effective to communicate the measured parameter to the transceiver. The at least one antenna can also be configured to receive energy to power the sensor, or data, or other information. In another embodiment, the implantable housing can be an injection port. 
     The antenna can be positioned in the housing in a variety of ways. For example, the implantable housing can include a support disposed therein having proximal and distal ends and extending along the longitudinal axis of the catheter. In an exemplary embodiment, the at least one antenna can include a plurality of antennae with each antenna disposed around the proximal and distal ends of the support and spaced radially about the support from an adjacent antenna. The antenna can be spaced around the support in a number of configurations. For example, each of the plurality of antennae can be spaced radially apart from one another, such as by about 180 degrees, about 120 degrees, about 90 degrees, or about 60 degrees, or at some other angular increment. In another exemplary embodiment, the at least one antenna can be in the form of a cylindrical coil antenna. 
     In another embodiment, a restriction system is provided and includes an implantable band configured to form a restriction in a pathway, and a housing associated with the band and having a catheter extending therefrom defining a longitudinal axis along a length thereof. An implantable sensor can be configured to measure at least one of a restriction system parameter and a physiological parameter, for example a fluid pressure of fluid in the band. At least one antenna can be associated with the housing and configured to emit a magnetic field toward an external device positioned on a tissue surface directly adjacent the housing regardless of a rotational orientation of the housing about an axis of the catheter extending from the housing. The antenna can have a variety of configurations, including a plurality of antennae extending along an axis aligned with the longitudinal axis of the catheter, and a cylindrical coil antenna having a longitudinal axis that is aligned with the longitudinal axis of the catheter. 
     Methods for communicating with an implantable restriction system are also provided, and in one embodiment the method can include providing a restriction system that is implantable within a patient to form a restriction in a pathway, positioning a communication device adjacent to a tissue surface of the patient, and activating the communication device to communicate with at least one antenna disposed within a housing forming part of the restriction system. The at least one antenna can emit a magnetic field toward the communication device regardless of a rotational orientation of the housing containing the at least one antenna about an axis of a catheter extending from the housing. In one embodiment, the communication device can communicate energy to provide power to a sensor in the restriction system that can be configured to measure at least one of a system parameter and a physiological parameter. The operational value(s) or the physiological value(s) measured by the sensor can be communicated to the external device by the at least one antenna in the restriction system. The communication device can have a variety of forms. For example, the communication device can be an external device located outside the body of the patient, or the communication device can be an internal device configured to be delivered internally within a patient&#39;s body. The antenna can have a variety of configurations. For example, the at least one antenna can include a plurality of antennae with each antenna oriented parallel to the longitudinal axis of the catheter and spaced radially therearound. The plurality of antennae can be configured to emit field lines in a plurality of planes extending through the longitudinal axis. The at least one antenna can also include a cylindrical coil antenna having a longitudinal axis that is aligned with the longitudinal axis of the catheter. The cylindrical coil antenna can emit field lines radially outward from the longitudinal axis of the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1A  is a schematic diagram of an embodiment of a food intake restriction system; 
         FIG. 1B  is perspective view of an embodiment of an implantable portion of the food intake restriction system of  FIG. 1A ; 
         FIG. 2A  is a perspective view of the food intake restriction device of  FIG. 1A ; 
         FIG. 2B  is a schematic diagram of the food intake restriction device of  FIG. 2A  applied about the gastro-esophageal junction of a patient; 
         FIG. 3  is a perspective view of an embodiment of the injection port housing of  FIG. 1A ; 
         FIG. 4  is a perspective view of an embodiment of the sensor housing of  FIG. 1A ; 
         FIG. 5  illustrates an embodiment of the sensor housing of  FIG. 1A ; 
         FIG. 6  is a schematic of an embodiment of a variable resistance circuit for the pressure sensor of  FIG. 5 ; 
         FIG. 7  is a block diagram showing an embodiment of internal and external components of the food intake restriction device of  FIG. 1A ; 
         FIG. 8  is a perspective view of one embodiment of the restriction system of  FIG. 1A-1B  showing a sensor housing including a plurality of antenna disposed therein; 
         FIG. 9  is a perspective view of one embodiment of a support for supporting the antenna disposed in the housing of  FIG. 8 ; 
         FIG. 10  is a perspective view of another embodiment of a support for supporting the antenna disposed in the housing of  FIG. 8 ; 
         FIG. 11  is a perspective view of another embodiment of an antenna configured to be disposed in a sensor housing; 
         FIG. 12  is a perspective view of a sensor housing including the antenna of  FIG. 11 ; 
         FIG. 13  is a perspective view of another embodiment of the restriction system of  FIG. 1A-1B  showing a housing including a plurality of antenna disposed therein; and 
         FIG. 14  is a perspective view of the embodiment of the housing of  FIG. 13  showing another embodiment of an antenna disposed therein. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
     Various exemplary methods and devices are provided for communicating with an implantable restriction system. In one embodiment, the implantable restriction system includes a housing having at least one internal antenna that can be in communication with an implantable sensor configured to measure system parameters (e.g., pressure) and/or physiological parameters. The internal antenna can be configured to emit a magnetic field toward an external device or an internally delivered device regardless of the rotational orientation of the housing about any axis to allow communication with the external device or the internally delivered device, for example, to transmit power to the implantable sensor and/or transfer and/or receive data between the internal antenna and the external or internally delivered device. 
     While the present invention can be used with a variety of restriction systems known in the art,  FIG. 1A  illustrates one exemplary embodiment of a food intake restriction 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. As shown, the implantable portion  10   a  includes an adjustable gastric band  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 band  20 , e.g., via a catheter  50 . The injection port  30  is configured to allow fluid to be introduced into and removed from the gastric band  20  to thereby adjust the size of the band  20  and thus the pressure applied to the stomach  40 . The injection port  30  can thus be implanted at a location within the body that is accessible through tissue. Typically, injection ports are positioned in the lateral subcostal region of the patient&#39;s abdomen under the skin and layers of fatty tissue. Surgeons also typically implant injection ports on the sternum of the patient. 
     The internal portion  10   a  can also include a sensing or measuring device that is in fluid communication with the closed fluid circuit in the implantable portion  10   a . In one embodiment, the sensing device is a pressure sensing device configured to measure the fluid pressure of the closed fluid circuit. While the pressure measuring device can have various configurations and can be positioned anywhere along the internal portion  10   a , including within the injection port  30  and as described further below, in the illustrated embodiment the pressure measuring device is in the form of a pressure sensor that is disposed within a sensor housing  60  positioned adjacent to the injection port  30 . The catheter  50  can include a first portion that is coupled between the gastric band  20  and the pressure sensor housing  60  and a second portion that is coupled between the pressure sensor housing  60  and the injection port  30 . While it is understood that the sensing device can be configured to obtain data relating to one or more relevant parameters, including physiological parameters, generally it will be described herein in a context of a pressure sensing device. 
     As further shown in  FIG. 1A , the external portion  10   b  generally includes a data reading device  70  that is configured to be positioned on the skin surface above the pressure sensor housing  60  (which can be implanted beneath thick tissue, e.g., over 10 cm thick) to non-invasively communicate (as described in detail below) with the pressure sensor housing  60  and thereby obtain pressure measurements. The data reading device  70  can optionally be electrically coupled (wirelessly or wired, as in this embodiment via an electrical cable assembly  80 ) to a control box  90  that can display the pressure measurements, other data obtained from the data reading device  70 , and/or data alerts. While shown in this example as being local to the patient, the control box  90  can be at a location local to or remote from the patient. 
     In some embodiments, the external portion  10   b  can include a sensing system configured to obtain data related to one or more relevant parameters, such as fluid pressure of the closed fluid circuit of the internal portion  10   a . For example, pressure in the closed fluid circuit can be measured through a Huber needle in fluid communication with the injection port  30 . An exemplary external pressure reading system is described in U.S. Publication No. 2006/0211912, entitled “External Pressure-Based Gastric Band Adjustment System and Method” which is hereby incorporated by reference. 
       FIG. 2A  shows the gastric band  20  in more detail. While the gastric band  20  can have a variety of configurations, and various gastric bands currently known in the art can be used with the present disclosure, in the illustrated embodiment the gastric band  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 loop such that the ends are secured to each other. Various mating techniques can be used to secure the ends  20   a ,  20   b  to one another. In the illustrated embodiment, the ends  20   a ,  20   b  are in the form of straps that mate together, with one laying on top of the other. In another embodiment, illustrated, for example, in  FIGS. 1B and 2B , a support structure at one end of the gastric band  20  can include an opening through which the other end of the gastric band  20  can feed through to secure the ends to one another. The gastric band  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 stomach to form an adjustable stoma for controllably restricting food intake into the stomach. 
     A person skilled in the art will appreciate that the gastric band can have a variety of other configurations. Moreover, the various methods and devices disclosed herein have equal applicability to other types of implantable bands. For example, bands are used for the treatment of fecal incontinence, as described in U.S. Pat. No. 6,461,292 which is hereby incorporated by reference. Bands can also be used to treat urinary incontinence, as described in U.S. Publication No. 2003/0105385 which is hereby incorporated by reference. Bands can also be used to treat heartburn and/or acid reflux, as disclosed in U.S. Pat. No. 6,470,892 which is hereby incorporated by reference. Bands can also be used to treat impotence, as described in U.S. Publication No. 2003/0114729 which is hereby incorporated by reference. 
       FIG. 2B  shows the adjustable gastric band  20  applied about the gastro-esophageal junction of a patient. As shown, the band  20  at least substantially encloses the upper portion of the stomach  40  near the junction with the patient&#39;s esophagus  42 . After the band  20  is implanted, preferably in the deflated configuration wherein the band  20  contains little or no fluid, the band  20  can be inflated, e.g., using saline, to decrease the size of the stoma opening. A person skilled in the art will appreciate that various techniques, including mechanical and electrical techniques, can be used to adjust the band  20 .  FIG. 2B  also shows an alternate location of a sensing device  41 , disposed in a buckle  43  of the band  20 . 
     The fluid injection port  30  can also have a variety of configurations. In the embodiment shown in  FIG. 3 , the injection port  30  has a generally cylindrical housing 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 a Huber 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 port  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, ceramic, glass, and polymeric materials, and the septum  34  can likewise be made from any number of materials, including silicone. 
     The 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. Publication No. 2006/0189888 and U.S. Publication No. 2006/0199997, which are hereby incorporated by reference. In general, the reading device  70  can non-invasively measure the pressure of the fluid within the implanted portion  10   a  even when the pressure sensing device is implanted beneath thick (at least over 10 cm, and possibly over 15 cm) subcutaneous fat tissue. The physician can hold the reading device  70  against the patient&#39;s skin near the location of the sensor housing  60  and/or other pressure sensing device location(s), obtain sensed pressure data and possibly other information as discussed herein, and observe the pressure reading (and/or other data) on a display on the control box  90 . The data reading device  70  can also be removably attached to the patient, as discussed further below, such as during a prolonged examination, using straps, adhesives, and other well-known methods. The data reading device  70  can operate through conventional cloth or paper surgical drapes, and can also include a disposal cover (not shown) that may be replaced for each patient. 
     As indicated above, the system  10  can also include one or more sensors for monitoring the operation of the gastric restriction system  10 . The sensor(s) can be configured to measure various operational parameters of the system  10  including, but not limited to, a pressure within the system, a temperature within the system, a peristaltic pulse event or frequency, the peristaltic pulse width, the peristaltic pulse duration, and the peristaltic pulse amplitude. In one exemplary embodiment, the system can include a sensor in the form of a pressure measuring device that is in communication with the closed fluid circuit and that is configured to measure the fluid pressure within the system, which corresponds to the amount of restriction applied by the adjustable gastric band to the patient&#39;s stomach. The sensor can also be configured to measure a variety of other parameters, for example, pulse count and pulse width. In use, measuring the fluid pressure, or any other control parameter of the system, can enable a physician (or other medical professionals) to evaluate the performance of the restriction system. In the illustrated embodiment, 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, and various exemplary locations and configurations are disclosed in more detail in commonly-owned U.S. Publication No. 2006/0211913 entitled “Non-Invasive Pressure Measurement In a Fluid Adjustable Restrictive Device,” filed on Mar. 7, 2006 and hereby incorporated by reference. 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. 
     Various pressure sensors known in the art can be used as the pressure sensor  62 , such as a wireless pressure sensor provided by CardioMEMS, Inc. of Atlanta, Ga., though a suitable Micro-Electro-Mechanical Systems (“MEMS”) pressure sensor may be obtained from any other source, including but not limited to Integrated Sensing Systems, Inc. (ISSYS) of Ypsilanti, Mich. and Remon Medical Technologies, Inc. of Waltham, Mass. 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 by a person skilled in the art that suitable pressure sensors can 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. 
     One embodiment of a configuration of the sensor housing  60  having the sensor  62  disposed within it is shown in  FIG. 5 . The sensor housing  60  in this example can be made of a two piece construction including a circuit board, which can be made of a hermetic material to serve as a hermetic component (bottom), and a hermetic top of compatible material bonded together to prevent fluid from contacting any elements disposed within the sensor housing  60 , except as discussed for the sensor  62 . The sensor housing  60  can be made from any biocompatible material appropriate for use in a body, such as a polymer, biocompatible metal, ceramic, glass, and other similar types of material. Furthermore, the sensor housing  60  can be made from any one or more of transparent (as shown in  FIG. 5 ), opaque, semi-opaque, and radio-opaque materials. A circuit board  64  including, among other elements, a microcontroller  65  (e.g., a processor), can also be disposed within the housing  60  to help process and communicate pressure measurements gathered by the sensor  62 , and also possibly other data related to the band  20 . (The circuit board  64  can also be part of the housing  60 , as mentioned above.) As further discussed below, the circuit board  64  can also include a transcutaneous energy transfer (TET)/telemetry coil and a capacitor. Optionally, a temperature sensor can be integrated into the circuit board  64 . The microcontroller  65 , the TET/telemetry coil, the capacitor, and/or the temperature sensor can be in communication via the circuit board  64  or via any other suitable component(s). The TET/telemetry coil and capacitor can collectively form a tuned tank circuit for receiving power from the external portion  10   b  and transmitting pressure measurements to a pressure reading device, e.g., the reading device  70 . Moreover, to the extent that a telemetry component associated with the pressure sensor  62  is unable to reach a telemetry device external to the patient without some assistance, such assistance can be provided by any suitable number of relays (not shown) or other devices. 
     In use, fluid can enter the sensor housing  60  through an opening  66  located anywhere on the housing&#39;s surface (here, the bottom surface) and come into contact with a pressure sensing surface  68  of the sensor  62 . The sensor  62  is typically hermetically sealed to the motherboard such that fluid entering the opening  66  cannot infiltrate and affect operation of the sensor  62  except at the pressure sensing surface  68 . The sensor  62  can measure the pressure of fluid coming into contact with the pressure sensing surface  68  as fluid flows in and out of the opening  66 . For example, the pressure sensing surface  68  can include a diaphragm having a deformable surface such that when fluid flows through the opening  66 , the fluid impacts the surface of the diaphragm, causing the surface to mechanically displace. The mechanical displacement of the diaphragm can be converted to an electrical signal by a variable resistance circuit including a pair of variable resistance, silicon strain gauges. One strain gauge can be attached to a center portion of diaphragm to measure the displacement of the diaphragm, while the second, matched strain gauge can be attached near the outer edge of diaphragm. The strain gauges can be attached to the diaphragm with adhesives or can be diffused into the diaphragm structure. As fluid pressure within band  20  fluctuates, the surface of the diaphragm can deform up or down, thereby producing a resistance change in the center strain gauge. 
     One embodiment of a variable resistance circuit for the sensor  62  is shown in  FIG. 6 . The circuit includes first and second strain gauges  96 ,  98  that form the top two resistance elements of a half-compensated, Wheatstone bridge circuit  100 . As the first strain gauge  96  reacts to the mechanical displacements of the sensor&#39;s diaphragm, the changing resistance of the first gauge  96  changes the potential across the top portion of the bridge circuit  100 . The second strain gauge  98  is matched to the first strain gauge  96  and athermalizes the Wheatstone bridge circuit  100 . First and second differential amplifiers  102 ,  104  are connected to the bridge circuit  100  to measure the change in potential within the bridge circuit  100  due to the variable resistance strain gauges  96 ,  98 . In particular, the first differential amplifier  102  measures the voltage across the entire bridge circuit  100 , while the second differential amplifier  104  measures the differential voltage across the strain gauge half of bridge circuit  100 . The greater the differential between the strain gauge voltages, for a fixed voltage across the bridge, the greater the pressure difference. Output signals from the differential amplifiers  102 ,  104  can be applied to the microcontroller  65  integrated into the circuit board  64 , and the microcontroller  65  can transmit the measured pressure data to a device external to the patient. If desired, a fully compensated Wheatstone bridge circuit can also be used to increase the sensitivity and accuracy of the pressure sensor  62 . In a fully compensated bridge circuit, four strain gauges are attached to the surface of diaphragm rather than only two strain gauges. 
       FIG. 7  illustrates one embodiment of components included in the internal and external portions  10   a ,  10   b . As shown in  FIG. 7 , the external portion  10   b  includes a primary TET coil  130  for transmitting a power signal  132  to the internal portion  10   a . A telemetry coil  144  is also included for transmitting data signals to the internal portion  10   a . The primary TET coil  130  and the telemetry coil  144  combine to form an antenna, e.g., the reading device  70 . The external portion  10   b , e.g., disposed in the control box  90 , includes a TET drive circuit  134  for controlling the application of power to the primary TET coil  130 . The TET drive circuit  134  is controlled by a microprocessor  136  having an associated memory  138 . A graphical user interface  140  is connected to the microprocessor  136  for inputting patient information, displaying data and physician instructions, and/or printing data and physician instructions. Through the use of interface  140 , a user such as the patient or a clinician can transmit an adjustment request to the physician and also enter reasons for the request. Additionally, the user interface  140  can enable the patient to read and respond to instructions from the physician and/or pressure measurement alerts, as discussed further below. 
     The external portion  10   b  also includes a primary telemetry transceiver  142  for transmitting interrogation commands to and receiving response data, including sensed pressure data, from the implanted microcontroller  65 . The primary transceiver  142  is electrically connected to the microprocessor  136  for inputting and receiving command and data signals. The primary transceiver  142  drives the telemetry coil  144  to resonate at a selected RF communication frequency. The resonating circuit can generate a downlink alternating magnetic field  146  that transmits command data to the microcontroller  65 . Alternatively, the transceiver  142  can receive telemetry signals transmitted from a secondary TET/telemetry coil  114  in the internal portion  10   a . The received data can be stored in the memory  138  associated with the microprocessor  136 . A power supply  150  can supply energy to the control box  90  in order to power element(s) in the internal portion  10   a . An ambient pressure sensor  152  is connected to microprocessor  136 . The microprocessor  136  can use a signal from the ambient pressure sensor  152  to adjust the received pressure measurements for variations in atmospheric pressure due to, for example, variations in barometric conditions or altitude, in order to increase the accuracy of pressure measurements. 
       FIG. 7  also illustrates components of the internal portion  10   a , which in this embodiment are included in the sensor housing  60  (e.g., on the circuit board  64 ). As shown in  FIG. 7 , the secondary TET/telemetry coil  114  receives the power/communication signal  132  from the external antenna. The secondary coil  114  forms a tuned tank circuit that is inductively coupled with either the primary TET coil  130  to power the implant or the primary telemetry coil  144  to receive and transmit data. A telemetry transceiver  158  controls data exchange with the secondary coil  114 . Additionally, the internal portion  10   a  includes a rectifier/power regulator  160 , the microcontroller  65 , a memory  162  associated with the microcontroller  65 , a temperature sensor  112 , the pressure sensor  62 , and a signal conditioning circuit  164 . The implanted components can transmit pressure measurements (with or without adjustments due to temperature, etc.) from the sensor  62  to the control box  90  via the antenna (the primary TET coil  130  and the telemetry coil  144 ). Pressure measurements can be stored in the memory  138 , adjusted for ambient pressure, shown on a display on the control box  90 , and/or transmitted, possibly in real time, to a remote monitoring station at a location remote from the patient. 
     As indicated above, the sensor housing can include at least at one antenna that can be configured to allow the implantable restriction system  10  to be powered by and/or communicate with an external device or an internally delivered device. A person skilled in the art will appreciate, however, that the at least one antenna can be located in various places, including but not limited to being located within the injection port  30 , with or without a separate housing. The antenna can be disposed in the housing in such a way as to allow effective communication between the antenna and an external device located adjacent to a skin surface or a device configured to be delivered internally within a patient&#39;s body, for example, to the gastro-intestinal tract. For example, the antenna can be disposed in a housing to allow the antenna to emit a magnetic field towards the external device or the internally delivered device regardless of the rotational orientation of the housing about an axis. This can be achieved in a variety of ways, including by orienting the antenna parallel to a longitudinal axis of a catheter extending from the housing. 
     While the housing that can contain the antenna, such as sensor housing  60  described above, is shown in  FIG. 1B  to have a disc-like configuration and in  FIG. 4  to have an elongate configuration, the housing can have a variety of configurations, including circular and rectangular configurations. In an exemplary embodiment, shown in  FIG. 8 , a housing  200  can have a generally elongate cylindrical configuration having proximal and distal ends  200   p ,  200   d  that define a longitudinal axis therebetween. A person skilled in the art will appreciate that the housing  200  can have any shape and size but it is preferably configured to be implanted in tissue and to contain at least one antenna  204  disposed therein. The housing  200  can also include a catheter, such as catheter  50 , extending therefrom. The catheter  50  can be coupled to the housing an inlet and/or an outlet that are in fluid communication with the fluid in the implantable portion  10   a . In order to allow for effective communication between the antenna  204  and an external device, the antenna  204  can extend within the housing  200  along an axis A aligned with a longitudinal axis of the catheter  50 . A person skilled in the art will appreciate that aligning the antenna  204  with the longitudinal axis of the catheter  50  includes the antenna  204  being co-axial with or parallel to the longitudinal axis of the catheter  50 . Thus, regardless of the rotational orientation of the housing  200  about the longitudinal axis of the catheter  50 , the antenna  204  can emit a magnetic field towards a predefined location on a tissue surface to allow the antenna  204  to communicate with the external device. A person skilled in the art will appreciate that the housing  200  can have any configuration so long as the antenna  204  can be positioned therein. Moreover, a person skilled in the art will appreciate that although the housing and the catheter are shown as being arranged in line, the components can be arranged in a variety of other ways, including in a T-configuration or a Y-configuration, and various exemplary configurations are disclosed in more detail in commonly-owned U.S. Publication No. 2006/0211913 entitled “Non-Invasive Pressure Measurement In a Fluid Adjustable Restrictive Device,” filed on Mar. 7, 2006 and hereby incorporated by reference. 
     The housing  200  can also include circuitry, as described above in  FIG. 5 , that can be disposed in the housing in a variety of ways. For example, in an exemplary embodiment, the circuitry can be anchored in the housing  200  using an attachment member  208  that is configured to couple the circuitry to the proximal end  200   p  of the housing  200 . A person skilled in the art will appreciate, however, that the circuitry can be disposed in the housing  200  in any manner and can be anchored to the housing  200  using any known means. 
     The at least one antenna  204  can also be disposed within the housing  200  in the housing in a variety of ways. In one embodiment, the housing  200  can include a support  202  disposed therein and configured to support the antenna  204 . The support  202  can have a variety of configurations, and can include proximal and distal ends  202   p ,  202   d  that define a longitudinal axis therebetween that can be parallel to or co-axial with the longitudinal axis of the catheter  50  extending from the housing  200 . In the illustrated embodiment, the proximal end  202   p  of the support  202  is coupled to the proximal end  200   p  of the housing  200  using an attachment member  206  that is configured to couple the support  202  to an inner proximal wall of the housing  200 . A person skilled in the art will appreciate, however, that the support  202  can be coupled to the housing  200  using a variety of techniques. For example, the support  202  can be fixedly coupled to the housing  200  using, for example, adhesives or fasteners, or the support  202  can be removably coupled to the housing  200 . A person skilled in the art will appreciate that the support  202  can be coupled to the housing  200  in any way that allows the antenna  204  to be positioned along the support  202 . The support  202  can also include features to accommodate any number of antennae  204  configured in any manner along the support  202 , as will be discussed in more detail below. 
     In order to facilitate communication with a device, such as a transceiver, that can be an external device or a device configured to be delivered internally within the body, such as in the gastro-intestinal tract, the housing  200  can include any number of antennae  204  in a variety of configurations to emit and/or receive field lines that are directed towards a tissue surface regardless of the orientation of the housing  200  about the axis, for example, the axis of the catheter  50  extending from the housing  200 . In one exemplary embodiment, this allows the antenna  204  to communicate with any device, including external and internal devices, regardless of the orientation of the housing  200  about any axis, for example, including an axis of the catheter  50  extending from the housing as the housing  200  rotates and/or flips about the axis of the catheter  50  when it is implanted. A person skilled in the art will appreciate that the housing  200  can include a plurality of antennae positioned in any configuration as long each antenna  204  is oriented substantially parallel to the longitudinal axis of the catheter  50  to allow the antennae  204  to emit magnetic field lines towards a location on a tissue surface about the housing  200  to facilitate communication with an external device or an internally delivered device. 
     For example, in one exemplary embodiment, the housing  200  can include a plurality of antennae  204  disposed around the proximal and distal ends  202   p ,  202   d  of the support  202  and spaced radially therearound in order to emit fields lines that allow the antennae  204  to communicate with the external device. The plurality of antennae can be spaced radially apart from one another by any angular increment, such as about 180 degrees, 120 degrees, 90 degrees, 60 degrees, 30 degrees, or some other increment. In the exemplary embodiment of  FIG. 8 , the first, second, and third antennae can be looped about the support  202  extending along the longitudinal axis thereof and are spaced radially apart from one another by about 120 degrees. In other words, each of the first, second, and third antenna can have a first portion extending along a side of the support  202  and a second portion extending along an opposed side of the support  202 . Thus, each of the portions of the first, second, and third antenna are spaced 60 degrees apart from one another. 
     The support can be also have a variety of configurations to support a plurality of antennae spaced radially therearound. For example,  FIG. 9  illustrates one exemplary embodiment of a support  222  adapted to support first and second antennae. The first and second antennae can be looped about the support  222  extending along the longitudinal axis thereof and can be spaced radially apart from one another by about 180 degrees. In other words, each of the first and second antenna can have a first portion extending along the a side  220 ,  224  of the support  222  and a second portion extending along an opposed side  226 ,  228  of the support  222 . Thus, each of the portions of the first and second antenna are spaced 90 degrees apart from one another. In order to accommodate the first and second antenna, the support  222  can have a generally elongate cross-shaped configuration. The support  222  can also include first and second opposed mounting grooves  230 ,  232  that are positioned opposite from each other along the sides  220 ,  228  of the support  222  to support the first antenna, and third and fourth mounting grooves  234 ,  236  that are positioned opposite from each other and at 90 degrees from the first and second opposed mounting grooves  230 ,  232  along the sides  224 ,  226  of the support  222  to support the second antenna. The mounting grooves  230 ,  232 ,  234 ,  236  can have a variety of configurations, but in the illustrated embodiment, are in the form of channels formed along the length of the sides  220 ,  224 ,  226 ,  228  of the support  222  and that are sized and shaped to receive the first and second antennae therein. Each mounting groove  230 ,  232 ,  234 ,  236  can include first and second opposed sidewalls  230   a ,  230   b ,  232   a ,  232   b ,  234   a ,  234   b ,  236   a ,  236   b , and the sidewalls can have a height that prevents the antenna from sliding out of the mounting grooves  230 ,  232 ,  234 ,  236  to hold the first and second antennae in place therein. A person skilled in the art will appreciate that the support  222  can have a variety of configurations to support the first and second antenna. For example, the support  222  can be in form of an elongate rectangle (not shown) having four sides with the mounting grooves  230 ,  232 ,  234 ,  236  formed in each of the sides of the elongate rectangle. Moreover, a person skilled in the art will appreciate that the support  222  can support the antenna without the use of the mounting grooves. 
     In another exemplary embodiment, first, second, and third antennae  304   a ,  304   b ,  304   c  can be spaced radially apart from one another by about 120 degrees. As shown in  FIG. 10 , a support  302  can be configured to accommodate the first, second, and third antenna and can have a generally hexagonical shape having six sides. Each pair of opposed sides of the support  302  can hold one of the first, second, and third antenna  304   a ,  304   b ,  304   c  along its length such that the antenna segments are spaced apart from one another at about 60 degrees increments. A person skilled in the art will appreciate that the support  302  can have variety of configurations and include a variety of additional features to support the first, second and third antenna  304   a ,  304   b ,  304   c . For example, the support  302  can include mounting grooves as describe above with respect to  FIG. 9  formed along each of the six sides of the support  302  to hold the first, second, and third antenna  304   a ,  304   b ,  304   c  therein and prevent the first, second, and third antenna  304   a ,  304   b ,  304   c  from sliding on the sides of the support  302 . Field lines  306  created by the first, second, and third antenna  304   a ,  304   b ,  304   c  run perpendicular to the longitudinal axis of the support  302  and the housing in which the antenna  304   a ,  304   b ,  304   c  and support  302  are disposed. Thus, when an external device is positioned adjacent to a skin surface or an internal device configured to be delivered internally within the body in order to communicate with the antennae  304   a ,  304   b ,  304   c , an antenna or other receiver/transmitter of the external device will align with the field lines  306  regardless of the orientation of the antenna  304   a ,  304   b ,  304   c  beneath the skin to allow for communication between the antenna  304   a ,  304   b ,  304   c  and the external or internal device. 
     A person skilled in the art will appreciate that the antenna can have any configuration and can be configured to emit a field in all directions. For example, the antenna illustrated in  FIGS. 8-10  are all configured to emit a field in all directions due to the looping of the antenna around the ends of the support. While the field emitted from the ends of the antenna can be weaker than the field emitted from the portions of the antenna extending along the length of the support, these antenna configurations will emit a field in all directions. In another exemplary embodiment, in order to achieve an antenna that emits a substantially equal field in all directions, the antenna can be formed to have a symmetrical configuration, for example, in the shape of a cube. This allows the antenna to emit a field of substantially the same magnitude in all directions regardless of the rotational orientation of the antenna about any axis. 
     In another exemplary embodiment, as shown in  FIGS. 11-12 , the antenna can be in the form of a cylindrical coil antenna  404  having a longitudinal axis A that is aligned with a longitudinal axis of the catheter  50  extending from the housing  400 . The cylindrical coil antenna  404  has a length and diameter that are configured to allow the antenna  404  to be disposed within the housing  400 , and can have a variety of configurations. For example, the coil antenna  404  can be formed from a single continuous antenna  404  in a coiled configuration, or can be formed from a plurality of separate circular antennae positioned adjacent one another to form a coiled shape. A support  402  can be configured to support the cylindrical coil antenna  404 , and in the illustrated embodiment is in the form of an elongate surface having a size that allows the support  402  to be disposed through the cylindrical coil antenna  404 . The support  402  can have a length that allows the support  402  to extend through the length of the antenna  404  and to allow the support  402  to be coupled to the housing  400 . The support  402  can be coupled to the housing in variety of ways. For example, in the illustrated embodiment, the support  402  to coupled to a proximal inner wall of the housing  400  using an attachment member  406 . Circuitry  408  also contained within the housing  400 , as described above, can also be attached to the housing  400  using the attachment member  406 . A person skilled in the art will appreciate that the circuitry  408  can be attached to the housing a variety of ways, including through the use of a separate attachment member. In the illustrated embodiment, the attachment member  406  includes first and second extensions extending therefrom. The first extension is configured to couple to the support  402  to couple the support  402  to the attachment member  406 , and the second extension is configured to couple to the circuitry  408  to couple the circuitry  408  to the attachment member  406 . In order to facilitate communication with an external device, the field lines created by the cylindrical coil antenna  404  run substantially parallel to a longitudinal axis of the catheter  50 , allowing communication with the external device regarding of the rotational orientation of the housing  400  about an axis of the catheter  50  extending therefrom. 
     While the catheter  50  illustrated in  FIGS. 8 and 12  is shown to be in line with and parallel to the antenna disposed within the housings  200 ,  400 ,  FIGS. 13-14  illustrate another exemplary embodiment of the housings  200 ,  400  having the antenna positioned perpendicular to the catheter  50 . Moreover, while the antenna illustrated in  FIGS. 8 and 12  are shown to be located within a housing also including the sensor,  FIGS. 13-14  illustrate the antenna located a within a housing of an injection port  30 . In order to facilitate communication with an external or internally deliverable device, the field lines created by the antenna shown in  FIG. 13  or the cylindrical coil antenna shown in  FIG. 14  are emitted in substantially all directions, allowing communication with the external or internal device regarding of the rotational orientation of the housing about any axis. A person skilled in art will appreciate that the antenna can be located within any housing within the restriction system to allow the antenna to communicate with an external or internally delivered device. 
     In use, the restriction system  10  shown in  FIGS. 1A-1B  can be implanted under the skin using techniques known in that art. For example, the gastric band  20  can be introduced into the patient&#39;s body and positioned around the stomach to restrict the pathway into the stomach, thus limiting food intake. The housing  60  (or  200 ,  400 ) and the port  30  can be implanted in tissue, preferably in the fascia, and they can be coupled to the band  20  to allow fluid communication therebetween. Preferably, the port  30  is anchored to a surface of the fascia, such that the port  30  is substantially parallel to the skin surface to allow access to the port  30 . The housing  60 ,  200 ,  400 , which is spaced a distance apart from the port  30  and preferably positioned on the fascia, can be coupled to the port  30  with the catheter  50 . 
     After implantation, it is necessary to be able to communicate with the implantable portion  10   a  of the restriction system  10 , for example, to transmit power to the restriction system and/or communicate system information to and from the restriction system  10 . The antennae are configured within the housing, for example, the housing of the sensor or the injection port, in any of the configurations described above in order to facilitate communication with an external device. The magnetic field lines emitted and/or received by the implanted antenna are emitted and/or received in such a manner as to allow an external antenna on the external device or an internal antenna on an internally delivered device to communicate with the implanted antennae regardless of the orientation of the antennae and the housing in which they are disposed about any axis. The implantable antenna can communicate with the external antenna of the external device or the internal antenna of the internally delivered device thereby allowing the implantable system to be powered and/or various system and/or physiological parameters (e.g., pressure readings) to be transmitted and/or received from the implantable antenna to/from the external or internal antenna. 
     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 invention. 
     Preferably, the invention described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and instrument 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 instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility. 
     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. 
     One of ordinary skill 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.