Abstract: An implantable medical device having a dual cell power source powering a high-power output circuit and a low-power control circuit. The power source includes a first, high-rate cell and a second, lower-rate cell having a rate capability less than a rate capability of the first, high-rate cell. The first and second cells are electrically connected to the output circuit and control circuit by circuitry. In one embodiment, the circuitry connects the first and second cells in parallel to the output circuit and the control circuit, and includes a switching circuit for selectively uncoupling the first, high-rate cell from the control circuit during a transient high power pulse. In another embodiment, the first and second cells are formed within a single case and are connected in parallel to the output circuit and the control circuit.

Abstract: An implantable medical device having a dual cell power source powering a high-power output circuit and a low-power control circuit. The power source includes a first, high-rate cell and a second, lower-rate cell having a rate capability less than a rate capability of the first, high-rate cell. The first and second cells are electrically connected to the output circuit and control circuit by circuitry. In one embodiment, the circuitry connects the first and second cells in parallel to the output circuit and the control circuit, and includes a switching circuit for selectively uncoupling the first, high-rate cell from the control circuit during a transient high power pulse. In another embodiment, the first and second cells are formed within a single case and are connected in parallel to the output circuit and the control circuit.

Abstract: An implantable medical device includes a control circuit for controlling the operation of the device and for obtaining physiological data from a patient in which the medical device is implanted. The implanted device also includes a communication circuit for transmitting the physiological data to an external device. A first power source is coupled to the control circuit and provides power to the control circuit. A second power source is coupled to the communication circuit and provides power to the communication circuit.

Abstract: A method of evaluating an electrochemical cell for a metallic contaminant-caused defect. The electrochemical cell is configured for use with an implantable medical device and includes an anode, a solid cathode and a liquid electrolyte. The method includes storing the cell at an elevated temperature following assembly for accelerating corrosion of possible metallic contaminants. A parameter of the cell related to cell voltage is then measured. An evaluation is made as to whether the cell is defective based upon this measured parameter.

Abstract: An electrochemical cell has a silver vanadium oxide cathode material formed into a pellet shape which expands as the cell is discharged. A cathode current collector circumferentially surrounds the cathode pellet and is in contact with the peripheral edge of the cathode pellet to prevent peripheral cathode expansion. The peripheral cathode current collector maintains a stable cell impedance during cell discharge. The cell has a D-shaped housing in which the cathode is disposed adjacent to a first interior surface, and a lithium anode is disposed adjacent to a second interior surface.

Abstract: An electrochemical cell has a cathode material formed into a pellet shape which expands as the cell is discharged. A cathode current collector circumferentially surrounds the cathode pellet and is in contact with the peripheral edge of the cathode pellet to prevent peripheral cathode expansion. The peripheral cathode current collector maintains a stable cell impedance during cell discharge.

Abstract: A lithium halide button cell formed of simplified sub-assemblies including one such subassembly in which molten cathode material is poured into a retaining ring and allowed to solidify therein before incorporation into the cell.

Abstract: A lithium halide button cell formed of simplified sub-assemblies including one such subassembly in which molten cathode material is poured into a retaining ring and allowed to solidify therein before incorporation into the cell.

Abstract: A method for making a primary cell comprising a lithium anode and an iodine containing cathode. The cell is first subjected to a preliminary conditioning at a predetermined time/temperature to effect a reduction in the impedance of the cell followed by cell discharge of at least 2 mAh per cm.sup.2 of the lithium anode surface prior to use or extended storage of the cell. The resulting primary cell has reduced variation in cell voltage and resistance and slower and more consistent self-discharge characteristics.

Abstract: A pacemaker having a fault-tolerant elective replacement indicator (ERI) triggering scheme in which transient excursions of parameters used as criteria for triggering ERI are rejected as triggering events. Periodic assessments of certain indicia of battery depletion are made, and subjected to a long-term low-pass filtering operation in order to reduce the effects of transient excursions of the indicia which result from non-ERI conditions. Over a long period of time (e.g., a day) predetermined threshold values of the indicia of interest must be exceeded a predetermined number of times in order for the device to issue an ERI. In one disclosed embodiment of the invention, the battery's loaded terminal voltage and internal impedance are used as indicators of the battery's depletion level. Periodically, these values are measured and converted to digital values.

Abstract: A pacemaker having a fault-tolerant elective replacement indicator (ERI) triggering scheme in which transient excursions of parameters used as criteria for triggering ERI are rejected as triggering events. Periodic assessments of certain indicia of battery depletion are made, and subjected to a long-term low-pass filtering operation in order to reduce the effects of transient excursions of the indicia which result from non-ERI conditions. Over a long period of time (e.g., a day) predetermined threshold values of the indicia of interest must be exceeded a predetermined number of times in order for the device to issue an ERI. In one disclosed embodiment of the invention, the battery's loaded terminal voltage and internal impedance are used as indicators of the battery's depletion level. Periodically, these values are measured and converted to digital values.

Abstract: A method and apparatus for measuring the depletion level (depth of discharge) of a lithium-iodine battery in an implantable medical device. A first set of measurements are made to determine the internal impedance of the battery, and a second set of measurements are made to determine the geometric capacitance of the battery, which has been found to correlate closely to the depth of discharge of the battery. The measurements are all made while the pacemaker is first temporarily decoupled from the medical device circuitry. The first measurements are made during a time window following a known change in resistive load across the terminals of the battery, and are capable of being correlated with 1-kHz qualification testing data made on the battery at the time of manufacture. The second measurements are made when the known load is periodically coupled and decoupled to the terminals of the battery at a rate of 80-kHz.