Patent ID: 8277389

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 indicates 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 device is configured to detect an auxiliary physiological signal in conjunction with detection of the acceleration correlative to the S1 heart sound, the control circuit configured to use the auxiliary physiological signal in determining the patient status indicator, the auxiliary physiological signal including a motion-related acceleration.