Patent ID: 7596412

Claim:
An implantable cardiac stimulation device comprising: at least one lead adapted to be implanted in a patient so as to be able to deliver therapeutic stimulation to the heart of the patient; a first sensor adapted to be implanted in the patient so as to sense a first signal indicative of electrophysiologic cardiac activity; a second sensor adapted to be implanted in the patient so as to provide a second signal indicative of hemodynamic output; a third sensor adapted to be implanted in the patient so as to provide a third signal indicative of patient activity; and a controller that receives the signals from the first, second and third sensors, wherein the controller performs a frequency domain evaluation of the signals to determine whether the second signal is frequency related to the first signal and whether the second signal is frequency related to the third signal, and upon determining: that the second signal is frequency related to the first signal, and the second signal is frequency related to the third signal, determines that the second signal is providing a reliable indication of the patient's physiological condition; and that the second signal is frequency related to the first signal, and the second signal is not frequency related to the third signal, determines that the second signal is providing a reliable indication of the patient's physiological condition.