A method of analysing cardiac functions in a subject using a processing systemis described. The method may include applying one or more electrical signalshaving a plurality of frequencies to the subject and detecting a response to theapplied one or more signals from the subject. A characteristic frequency canthen be determined from the applied and received signals, and at least one componentof the impedance (e.g., reactance, phase shift) can be measured at the characteristicfrequency. Thus, the impedance or a component of impedance at a characteristicfrequency can be determined for a number of sequential time instances. A new characteristicfrequency may be determined within a cardiac cycle (e.g., with each sequentialtime instant) or the same characteristic frequency may be used throughout thecardiac cycle during which instantaneous values of impedance (or a componentof impedance) are determined. These instantaneous values may be used to "determineone or more indicia of cardiac function.
