Abstract: A body implantable ventricular cardioverting system. Circuitry is provided which detects the onset of a malignant ventricular tachyarrhythmia and provides a cardioverting signal in response thereto. The cardioverting signal has an energy level that is high relative to the pacing threshhold but below that necessary for defibrillation. In this manner, a ventricular tachyarrhythmia can be cardioverted before the onset of fibrillation and at a lower energy than required for defibrillation. Dependent on such factors as patient threshholds, the tissue/electrode interface and the electrode system employed, the energy level of the cardioverting signal is from 5 millijoules to 15 joules. The system can be configured such that increasingly malignant tachyarrhythmias result in higher energy cardioverting signals, including signals capable of defibrillation.

Abstract: A body implantable ventricular cardioverter. Circuitry is provided which detects the onset of a malignant ventricular tachyarrhythmia and provides a cardioverting signal in response thereto. The cardioverting signal has an energy level that is high relative to the pacing threshold but below that necessary for defibrillation. In this manner, a ventricular tachyarrhythmia can be cardioverted before the onset of fibrillation and at a lower energy than required for defibrillation. Dependent on such factors as patient thresholds, the tissue/electrode interface and the electrode system employed, the energy level of the cardioverting signal is from 5 millijoules to 15 joules. The system can be configured such that increasingly malignant tachyarrhythmias result in higher energy cardioverting signals, including signals capable of defibrillation.

Abstract: Apparatus for processing waveform signals of physiological origin. The apparatus includes circuitry for developing a signal representative of the peak-to-peak amplitude between each waveform signal peak and the next successive waveform signal peak as well as circuitry for developing a signal representative of the slew rate of the waveform signal between successive waveform signal peaks. In a preferred embodiment, developed signals are stored in resettable memories, the memories being reset on the occurrence of a sign or polarity change in the slope of the waveform signal. Sampling circuitry is provided for establishing a maximum peak-to-peak amplitude within the waveform signal as well as its associated slew rate. Within the context of an ECG, the maximum peak-to-peak amplitude and associated slew rate represent the QRS complex and the apparatus of the present invention may be employed within a pacemaker as a sense amplifier.

Abstract: A demand anti-arrhythmia pacemaker having a plurality of electrodes adapted for connection to a heart for sensing depolarizations. A first responsive circuit provides stimulation signals to at least one area of the heart if a depolarization corresponding to a natural heartbeat fails to occur within a first predetermined time period. A second responsive circuit provides stimulation signals to the heart in a plurality of areas in response to sensed depolarizations which occur within a second predetermined time period.

Abstract: A bipolar electrode of the type adapted to be electrically and physically coupled to a body tissue is disclosed as comprising a helix-configured electrode to be screwed into the body tissue and an annular-shaped electrode disposed about the helical electrode for surface contact with the tissue, and first and second flexible electrodes coupled respectively to the aforementioned electrodes. Each of the flexible electrodes has a proximal end adapted for connection to a power supply and a distal end portion for connection to the one of the aforementioned electrodes. The helix-configured electrode is partially covered with an inert insulating material with the tip of the helical electrode being exposed. The annular-shaped electrode is disposed about the helical electrode whereby an intense field is formed between the annular-shaped electrode and the exposed tip of the helical electrode, thus insuring efficient stimulation of the tissue and minimum current drainage of the power supply, e.g. a battery.