Effective arterial elastance (E/sub a/) is a non-specific measure of the arterial load

Effective arterial elastance (E/sub a/), defined as the ratio of left ventricular (LV) end-systolic pressure and stroke volume, lumps the steady and pulsatile components of the arterial load in a concise way. Combined with E/sub max/, the slope of the LV end-systolic pressure-volume relation, E/sub a//E/sub max/ has been used to assess heart-arterial coupling. A mathematical heart-arterial interaction model was used to study the effects of changes in peripheral resistance (R, 0.6-1.8 mmHg/(ml/s)) and total arterial compliance (C, 0.5-2.0 ml/mmHg) covering the human patho-physiological range. E/sub a/, E/sub a//E/sub max/, LV stroke work and hydraulic power were calculated for all conditions. Multiple linear regression analysis revealed a linear relation between Ea, R/T and 1C: E/sub a/=-0.13+1.02 R/T+0.31/C (with T cycle length) indicating that R/T contributes about 3 times more to Ea than arterial stiffness (1/C). It is demonstrated that different patho-physiological combinations of R and C may lead to the same E/sub a/ and E/sub a//E/sub max/, but can result in differences of 10% in stroke work and 50% in maximal power.