Abstract: An ICD detection method for sensing the occurrence of an R-wave improves the ability to distinguish R-waves from noise through the use of variable declining sensitivity thresholds. The method includes the consideration of the amplitude of at least the previous most recent R-wave to determine a declining threshold of sensitivity used to recognize a subsequent electrical signal as an R-wave. In the method, the amplitude of the previous R-wave may be classified, based upon amplitude, and based upon the classification, a desirable time constant for the declining threshold of sensitivity is provided as an exponential or reverse exponential decay. Alternatively, a piece wise use of various decay formulas may be combined and used to avoid false recognition of noise as an R-wave.

Abstract: An apparatus and method for detecting the location of subsurface markers in a formation proximate to a borehole. The apparatus includes marker detectors in a housing having at least two housing sections attached in an initial orientation. The distance between the detectors is measured under controlled conditions with a calibration bar. The initial attached orientation between the housing sections is identified with a calibrator, and deviations from the initial attached orientation are identified by the calibrator after the housing sections are detached and reattached. The calibrator permits well site corrections to be made to the housing sections without recalibration. Gauges permit corrections for temperature and pressure fluctuations, and the corrected distances between the housing detectors is computed.

Abstract: A circuit detectable arrangement of a plurality of medical electrodes is provided with each electrode having an electrically nonconductive backing layer, a layer of electrically conductive adhesive disposed on the backing layer and a lead wire extending therefrom and electrically connected with the conductive adhesive. More specifically, a first electrode is disposed on an electrically nonconductive liner, a second electrode is disposed on an electrically nonconductive liner, and an electrical connector is provided between the first and second electrodes for electrically completing a circuit connecting the lead wire of the first electrode to the lead wire of the second electrode. Preferably, the backing layers of the first and second electrodes each include a conductor portion, and the electrical connector is connected between the conductor portion of the backing layer of the first electrode and the conductor portion of the backing layer of the second electrode.

Abstract: A method and apparatus continuously, automatically, and adaptively facilitate the electrical activity of a patient's heart by pulsing the heart with current. The method and apparatus further continuously, automatically, and adaptively monitor the resulting electrical activity of the patient's heart to assess the patient's likelihood for myocardial electrical instability. The method comprises the steps of injecting current across the patient's heart, monitoring the patient's electrocardiogram for the effects of these current pulses, and adapting the current pulses continuously and automatically to maximize the effects, thereby assessing a patient's likelihood of sudden cardiac death.

Abstract: A method and apparatus for inducing fibrillation generates a continuous fibrillation waveform from the internal battery source of an implantable cardioverter defibrillator. The continuous fibrillation waveform has a voltage of at least 5 volts and not more than 50 volts and a duration of not less than 500 milliseconds and is applied though the at least two implantable electrodes so as to induce fibrillation in the heart of the human patient.

Abstract: The present invention is a physician's interface expert system that allows a physician not well versed in ICD parameters to program at least one parameter into an ICD using the physician's existing knowledge of the patient's medical history. The programmable ICD system is composed of an implantable portion and a programming device external from the patient's body. The implantable portion has pulse generating circuitry, control circuitry including parameter storage, a receiver and at least one electrical lead for placement in the patient's heart. The programming device contains an operator interface device that receives a first set of values from the operator. A translator is provided in the programming device for translating the first set of values into a second set of values formatted in accordance with the programmable parameter settings of the implanted device. Finally, a transmitter is provided in the programming device to transmit the second set of values to the receiver of the implanted device.

Abstract: A method and apparatus continuously, automatically, and adaptively facilitate the electrical activity of a patient's heart by pulsing the heart with current. The method and apparatus further continuously, automatically, and adaptively monitor the resulting electrical activity of the patient's heart to assess the patient's likelihood for myocardial electrical instability. The method comprises the steps of injecting current across the patient's heart, monitoring the patient's electrocardiogram for the effects of these current pulses, and adapting the current pulses continuously and automatically to maximize the effects, thereby assessing a patient's likelihood of sudden cardiac death.

Abstract: An implantable defibrillator system for generating biphasic waveforms comprises a self-contained human implantable housing containing a capacitor system for storing an electrical charge, a power supply for charging the capacitor system, and a controller for selectively discharging the electrical charge as a biphasic countershock to be delivered through at least two electrodes in response to a sensing of a cardiac dysrhythmia in the human patient. The controller includes a system for controlling a first duration of a first phase of the biphasic countershock such that the discharge of the electrical charge is of a first polarity and the first duration is variable and a system for controlling a second duration of a second phase of the biphasic countershock such that the discharge of the electrical charge is of a second polarity that is opposite from the first polarity and the second duration is fixed.

Abstract: An audio system employs a microcontroller to supervise the operation of an audio system including a digitally controlled audio processor which controls at least a wideband and a narrowband gain for the audio signal. The narrowband gain may preferably comprise a bass boost to the audio signal. Clipping distortion of the audio signal is avoided by sensing clipping in a power amplifier and reducing the digital commands for the wideband gain and the narrowband gain according to a method which reduces narrowband gain in preference to the wideband gain. After the narrowband gain is reduced to a predetermined gain, the wideband gain may be reduced if clipping persists. When clipping ceases, the narrowband gain is likewise restored to its original gain in preference to restoring of the wideband gain.

Abstract: A method and apparatus for detecting heart disease from an electrocardiogram (ECG) is disclosed. The method comprises the steps of acquiring the ECG signals, correcting for signal variability caused by breathing, and calculating the level of remaining variability due to myocardial function. The apparatus comprises a signal input system, a storage system, a microprocessor and an output system. The microprocessor has program logic for processing signal data in accordance with the above method.

Abstract: This invention provides a sound sensor apparatus for reception of bio-acoustic signals from the body of a patient and for use with a medical diagnostic device. The apparatus comprises a unitary containment structure of a pliable, adhering material for conforming placement on the patient body surface. A sound sensing transducer is embedded in the containment structure to receive and convert bio-acoustic signals to electrical signals. A cable is communicatively linked to the sound sensing transducer for transmitting the electrical signals to the medical diagnostic device. The composition of the pliable containment structure material is a polymeric mixture substantially acoustically matched to the patient body. The sound sensing transducer is preferably a piezoelectric crystal transducer constructed of a composite material which comprises at least 65 percent by weight lead, at least 20 percent by weight zirconium, and at least 10 percent by weight titanium.

Abstract: A switching arrangement including a current switch for providing a low impedance electrical path therethrough in response to the application of triggering signals thereto, and for providing a high impedance electrical path in the absence of the triggering signals, is connected in an electrical path between a load and an AC voltage source. A control circuit is provided for applying triggering signals to the current switch when enabling power is applied thereto. A normally open switch provides enabling power derived from the AC voltage source to the control circuit when the normally open switch is closed. A normally closed switch provides enabling power derived from current which flows through the current switch to the control circuit when the normally closed switch is closed. Upon momentary closure of the normally open switch, the switching arrangement is turned on.