The present disclosure relates to a method and system for processing a cardiac sensor output wherein blood flow and simulated aortic blood pressure are derived from sensed aortic blood pressure using an arterial flow model and values for an arterial flow parameter . The simulated aortic blood pressure is matched to a portion of the sensed blood pressure in one cardiac cycle by manipulating at least one of the values for the arterial flow parameter of the arterial flow model .(FIG.