Patent ID: 8007442

Claim:
A device comprising: a transducer configured to convert an acceleration correlative to a S1 heart sound into an electrical signal; a control circuit coupled to the transducer, the control circuit configured to receive the electrical signal, identify the acceleration correlative to the S1 heart sound, determine a maximum amplitude of the acceleration correlative to the S1 heart sound and a minimum amplitude of the acceleration correlative to the S1 heart sound, and determine a patient status indicator using an indication of a peak-to-peak difference between the maximum amplitude of the acceleration correlative to the S1 heart sound and the minimum amplitude of the acceleration correlative to the S1 heart sound, wherein the patient status indicator is correlative to at least one of contractility or a maximum time rate of change of pressure within a ventricle of a heart during a cardiac cycle, wherein the control circuit is configured to use an auxiliary physiological signal to select the accelerations used in the determination of the patient status indicator, the auxiliary physiological signal indicative of at least one of physical activity or respiration.