Abstract: A processing system and method are provided for deriving an improved hemodynamic indicator from cardiac wall acceleration signals. The cardiac wall acceleration signals are provided by a cardiac wall motion sensor that responds to cardiac mechanical activity. The cardiac wall acceleration signals are integrated over time to derive cardiac wall velocity signals, which are further integrated over time to derive cardiac wall displacement signals. The cardiac wall displacement signals correlate to known hemodynamic indicators, and are shown to be strongly suggestive of hemodynamic performance. An implantable cardiac stimulating device which uses cardiac wall displacement signals to detect and discriminate cardiac arrhythmias is also provided.