An implantable system acquires intracardiac impedance with an implantable lead system. In one implementation, the system generates frequency-rich, low energy, multi-phasic waveforms that provide a net-zero charge and a net-zero voltage. When applied to bodily tissues, current pulses or voltage pulses...http://www.google.de/patents/US7945326?utm_source=gb-gplus-sharePatent US7945326 - Tissue characterization using intracardiac impedances with an implantable lead system
