Implantable defibrillator system employing capacitor switching networks

Abstract

The present invention uses switching networks for the predetermined combination of capacitor-discharge waveforms in order to approximate a particular waveform for application to the heart muscle in a defibrillation procedure. These are usually biphasic waveforms, or waveforms exhibiting a positive pulse followed immediately by a negative pulse. Examples of the discharge-process possibilities are those of two capacitors in parallel, two in series, two in sequence, or a capacitor or capacitors with polarity inverted. Adding capacitors and switches expands the range of possibilities and provides waveforms 'tailoring' under the guidance of a switching network that can be digitally programmed from an external programming console, much as in the digital programming of a pacemaker system. Digital signals are transmitted to the implanted system using infrared, visible, RF electromagnetic radiation, or ultrasound radiation. The use of multiple capacitors rather than just a single capacitor makes it possible to pack the components more densely, and in the case of some waveforms, to use less total capacitance than in the prior art, both factors contributing to very desirable size reduction for the implantable defibrillator. One or more implanted batteries are used to meet the heavy energy requirements of defibrillation, and these are recharged, one at a time, and after full discharge, by means of implanted series-array photovoltaic devices, preferably monolithic.