Abstract: Medical device and methods are provided for controlled drug delivery in a cardiac patient. The device includes an implantable drug delivery module comprising reservoirs containing a drug and a control means for selectively releasing an effective amount of drug from each reservoir; one or more electrodes or sensors for cardiac monitoring, stimulation, or both; and a microcontroller for controlling operational interaction of the drug delivery module and the cardiac electrode. The electrodes may comprise ECG monitoring, cardioversion, or cardiac pacing electrodes.

Abstract: An atrial defibrillation system includes an implantable atrial defibrillator including an atrial fibrillation detector and an atrial cardiovertor, and an external communication device dimensioned to be hand-held and including an RF transmitter for transmitting a command signal to the implanted defibrillator. The implantable defibrillator includes a receiver for receiving the command signal, activation means responsive to receipt of the command signal for activating the atrial fibrillation detector and the atrial cardiovertor if the atrial fibrillation detector detects atrial fibrillation, and an RF transmitter for transmitting an acknowledgment signal to the external communication device responsive to the receiver receiving the command signal. The external communication device further includes a receiver for receiving the acknowledgment signal and an indicator for providing a perceptible indication responsive to receipt of the acknowledgment signal.

Abstract: An implantable atrial defibrillator applies cardioverting electrical energy to the atria of a human heart in response to detection of an atrial fibrillation episode and stores selected data associated with the detected atrial fibrillation episode. The atrial defibrillator includes a cardiovertor which provides successive applications of cardioverting electrical energy to the atria of the heart until one of the pulses successfully cardioverts the atria. A memory system stores selected heart activity data in connection with the detected episode including heart activity data related to initial detection of the atrial fibrillation episode and heart activity data occurring from before and until after the application of the cardioverting electrical energy which successfully cardioverts the atria of the heart.

Abstract: A cardiac monitor which is fully implantable beneath the skin of a patient monitors heart rate variability of a human heart. The heart rate monitor includes at least one electrode which establishes electrical contact with the heart. During a heart monitoring period, time intervals between adjacent heart beats are determined for generating heart rate data. The heart rate data is stored in a memory which is accessed after the completion of the heart monitoring period for generating a heart rate variability factor. The heart rate variability factor is stored in memory for later transmission to a nonimplanted external receiver.

Abstract: An implantable cardiac monitor is arranged for detecting both arrhythmias and ischemia of the human heart. The monitor includes subcutaneous electrodes for establishing electrical contact with the heart and a sense amplifier coupled to each electrode for generating an electrocardiogram of a heart beat sensed at each of the electrodes. The electrocardiograms are digitized and the digital samples thereof are stored in a memory. A microprocessor processes the digital samples of the electrocardiograms and generates characterizing data indicative of the physiology of the heart. The cardiac monitor includes telemetry to permit the cardiac data to be interrogated externally of the patient for obtaining the generated cardiac data indicative of arrhythmic and ischemic episodes.

Abstract: An implantable cardiac monitor is arranged for detecting both arrhythmias and ischemia of the human heart. The monitor includes subcutaneous electrodes for establishing electrical contact with the heart and a sense amplifier coupled to each electrode for generating an electrocardiogram of a heart beat sensed at each of the electrodes. The electrocardiograms are digitized and the digital samples thereof are stored in a memory. A microprocessor processes the digital samples of the electrocardiograms and generates characterizing data indicative of the physiology of the heart. The cardiac monitor includes telemetry to permit the cardiac data to be interrogated externally of the patient for obtaining the generated cardiac data indicative of arrhythmic and ischemic episodes.

Abstract: An improved control system for a neural stimulator allowing either the patient or physician to effect the level of output by application of an external magnet. Such application of a magnet for a predetermined period of time initiates an incrementally increasing output, under control of an implanted microprocessor, allowing human feedback from the patient to determine the effective level of output current to fix the output at the selected effective level.

Abstract: The apparatus comprises: a comparator for comparing the voltage at which the constant current pulses are being supplied to the load with an increasing reference voltage; a counter for counting the number of voltage pulses that are greater in magnitude than the increasing reference voltage over a sampling period; and signal processing circuitry for correlating the count of pulses over the sampling period with the impedance of the load required to generate that number of constant current pulses at the voltage required for same.

Abstract: The stimulation output of an implanted cardiac pacer is applied between a cathode at the end of a pacer lead in the heart and an anode whose location is programmable. An electronic switch accessed via programming designates the pulse generator pace as the anode for an additional electrode located near the end of the pacer lead, thus changing the pacer from unipolar to bipolar operation or vice-a-versa after implantation. Different programming pulse rates are used to program different functional characteristics. For example, pulses at one rate select mode, high or low frequency range, sensitivity and anode location while pulses at another frequency set the pulse generation rate and output current.

Abstract: The stimulation output of an implanted cardiac pacer is applied between a cathode at the end of a pacer lead in the heart and an anode whose location is programmable. An electronic switch accessed via programming designates the pulse generator case as the anode for an additional electrode located near the end of the pacer lead, thus changing the pacer from unipolar to bipolar operation or vice-a-versa after implantation. Different programming pulse rates are used to program different functional characteristics. For example, pulses at one rate select mode, high or low frequency range, sensitivity and anode location while pulses at another frequency set the pulse generation rate and output current.

Abstract: An improved control system for a neural stimulator allowing either the patient or physician to effect the level of output by application of an external magnet. Such application of a magnet for a predetermined period of time initiates an incrementally increasing output, under control of an implanted microprocessor, allowing human feedback from the patient to determine the effective level of output current to fix the output at the selected effective level.