A system to measure intracardiac impedance includes implantable electrodes and a medical device. The electrodes sense electrical signals of a heart of a subject. The medical device includes a cardiac signal sensing circuit coupled to the implantable electrodes, an impedance measurement circuit coupled...http://www.google.com/patents/US20070043394?utm_source=gb-gplus-sharePatent US20070043394 - Intracardiac impedance and its applications
