Contractile element ( CE) power per unit volume (defined as the product of wall stress and CE velocity) and series elastic ( SE) power per unit volume (defined as the product of wall stress and SE velocity), and their corresponding work terms, have been determined over a complete cardiac cycle in 39 patients comprising 5 clinical groups, using pressure and volume data acquired from single-plane cineangiography. The results indicate that there are four characteristic power curves: power generated by the CE during systole, power stored by the SE during systole, power dissipated by the CE during diastole and power released by the SE during diastole. CE power is distributed as 43% internal and 57% external, while CE work is distributed as 16.5% internal and 83.5% external. For compensated volume overload, dissipated CE power is less negative ( P < 0.025). For decompensated volume overload, stored SE power is significantly less negative ( P < 0.05) and CE power is redistributed so that a lesser percent (33%) is internal and a greater percent (67%) is external ( P < 0.05). For compensated pressure overload, stored SE power is less negative ( P < 0.025). CE power is redistributed so that a lesser percent (18.5%) is internal and a greater percent (81.5%) is external ( P < 0.0005). CE work is also redistributed such that only 12% is internal while 88% is external ( P < 0.025). For congestive cardiomyopathy, all six of the work and power parameters are significantly altered from normals. These results suggest that: (1) it is important to look at passive events in the cardiac cycle, as well as active events, (2) peak power parameters are more physiologically descriptive of pathological states than are time-averaged work parameters, (3) changes in ventricular elasticity, although not precisely known, could account for some of the observed alterations, (4) parameters are uniformly sensitive to intrinsic myocardial disease, and (5) CE and SE work and power parameters correlate poorly with standard hemodynamic parameters.