Methods and devices are provided for gathering impedance data related to implantable restriction devices. In general, the methods and devices can enable patients, health care providers, and others to use gathered data as a feedback mechanism to non-invasively monitor efficacy of an implantable restriction device in a patient and to identify, modify, and/or prescribe a treatment plan for the patient considering the gathered data. Impedance data can be gathered and analyzed for tissue proximate to the restriction device, e.g., a fat pad between a gastric band and the patient's stomach. Electrodes in contact with the tissue can measure an impedance of the tissue, with the impedance between the electrodes changing as the tissue reduces in size (e.g., as fat cells shrink) and/or changes configuration.

Methods and devices for measuring impedance in a gastric restriction system

A gas column pressure-measuring catheter (12) which is insertable into a mammalian body for purposes of transmitting pressure changes from a location within the mammalian body to a pressure sensor (14) which is either incorporated into, or connected to, the catheter (12). In a preferred embodiment, the gas column pressure-measuring catheter (12) comprises an elongate catheter body (20) having a gas-filled lumen (22) extending longitudinally therethrough, and a gas-filled membrane-walled chamber (38, 40) positioned on the catheter body in communication with the gas-filled lumen such that pressure changes exerted against the outer surface of the membrane-walled chamber will result in the transmission of pressure changes through the gas-filled catheter lumen (22). The gas-filled membrane-walled chamber may be located on the side wall of the catheter body (20) or on the distal end of the catheter body (20).

Gas column pressure monitoring catheters

An implantable restriction device is configured to provide a restriction in a patient as a function of the pressure of fluid. The implantable restriction device includes one or more pressure sensors configured to sense pressure of the fluid within the implantable restriction device. Pressure data obtained by the one or more pressure sensors may be communicated to a device located external to the patient, such as a data logger, using telemetry coils or other communicators. The data logger may store the pressure data, and may communicate the pressure data to a remote location via a network such as the Internet. A docking station may be provided to couple the data logger to a network and/or to recharge a cell in the data logger.

Monitoring of a food intake restriction device

A fluid pressure monitoring system for a balloon catheter includes a pressure transducer in fluid communication with the interior of the balloon. The pressure transducer includes elements for providing an electrical signal which is a function of the pressure in the interior of the balloon. An electronic digital display is responsive to the electrical signal from the pressure transducer to display the balloon pressure measured by the pressure transducer. The system is especially suited for coronary angioplasty in which a catheter is inserted through blood vessels in the human body to the vicinity of a stenosis. The catheter carries an inflatable balloon to the vicinity of the stenosis, where it is inflated, and the fluid pressure monitoring system of the present invention detects and digitally displays to the cardiologist the pressure inside the inflated balloon. The pressure transducer is interchangeable with standard pressure transducers such as those used for monitoring substantially lower pressure such as a person's blood pressure and the digital display is also used to display a person's blood pressure. Alternatively, the balloon pressure transducer may be used with standard blood pressure monitors.

Medical pressure sensing and display system

An implantable system having internal circuitry configured to withstand a pre-determined amount of sterilization radiation is provided. In general, the system includes an internal control module in electrical communication with an implantable medical device. The internal control module can include a circuit board configured to withstand radiation and/or any number of integrated circuits (e.g., application specific integrated circuits) wherein the circuits or at least some portion thereof are fabricated so as to withstand some amount of radiation. For example, some portion of the circuitry can be fabricated utilizing radiation compliant material(s), silicon-on-insulator technology, and/or gallium arsenide technology. Additionally, the circuitry can include various components which are inherently resistant to such radiation (e.g., components fabricated utilizing magnetic field based technology, surface acoustical wave devices, etc.). A method of sterilizing an implantable medical device via radiation is also provided.

System and method of sterilizing an implantable medical device

Sensitivity or span calibration is adjusted to a desired value by (1) noting the display indication with the reference side of the transducer at atmospheric pressure, (2) substituting a known offset pressure for atmospheric pressure on the reference side, to produce a new display indication, and (3) adjusting the display to produce that amount of displacement (between the display indications in steps 1 and 2) which corresponds to the known offset pressure multiplied by the desired calibration value. With the sensitivity or span calibration adjusted to a desired value, the zero point of the display is adjusted by (1) independently measuring the mean of the actual pressure, (2) noting the mean value of the display indication, and (3) adjusting the zero point to eliminate discrepancy between the mean value of the display and the mean of the actual pressure. The apparatus has a port for a substitute reference pressure, and an external pressure gauge for measuring the mean pressure through an auxiliary lumen of the catheter.

Arnold St. J. Lee

Papers

Method and apparatus for "zeroing" and calibrating a catheter-tip gauge-pressure transducer