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.