Subcutaneous cardiac signal discrimination employing non-electrophysiologic signal

Abstract

A cardiac monitoring and/or stimulation system includes a housing coupled to a plurality of electrodes configured for subcutaneous non-intrathoracic sensing. A signal processor receives a plurality of composite signals associated with a plurality of sources, separates a signal from the plurality of composite signals, and identifies the separated signal as a cardiac signal using information derived from a non-electrophysiologic sensor, such as an accelerometer or acoustic transducer. The signal processor may iteratively correlate separated signals from the plurality of composite signals with a non-electrophysiologic sensor signal until the cardiac signal is identified.

What is claimed is: 
     
         1 . A device, comprising:
 an implantable housing;   a plurality of subcutaneous non-intrathoracic electrodes configured to sense a plurality of electrical signals;   a sensor that senses a non-electrophysiologic signal; and   a signal processor provided in the housing and coupled to the sensor and the plurality of subcutaneous non-intrathoracic electrodes, the processor configured to initiate a detection window at a start time determined from use of the non-electrophysiologic signal, and to identify a cardiac signal from the plurality of electrical signals using the detection window.