Abstract: A method and apparatus for detecting and reverting pathological heart rhythms of a patient are disclosed. A plurality of electrical heart rhythm signals of the patient are sensed at two different locations within the heart. The cross-phase spectra of the sensed heart rhythm signals for each heartbeat are calculated and such heart rhythms are classified based upon the information contained in the cross-phase spectra. Appropriate therapy is then delivered to the patient's heart to revert those of the heart rhythms that are classified as pathological.