Different estimates of cardiac power: Relationship to altered loading conditions

Peak instantaneous power is a prognostic index of LV function but is difficult to measure. It is relatively load independent when corrected by preload (EDV²). Easier to acquire power estimates have been proposed - including mean and simplified power. These require only echo Doppler flow and cuff pressures, but their relationship to invasively derived results has not been studied. Using a well-validated numerical model of the cardiovascular system, different estimates of power were compared for varying preload, afterload, and contractility. All power results were divided by EDV². Estimates of power correlate with peak power over a wide range of physiology. Corrected power estimates were independent of preload and afterload, but predictably increased with contractility. Different estimates of preload corrected power can be derived from non-invasively obtained variables and correlate with corrected peak instantaneous power.