Relation of effective arterial elastance to arterial system properties.
Effective arterial elastance (E(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(max), the slope of the LV end-systolic pressure-volume relation, E(a)/E(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 x ml(-1) x s) and total arterial compliance (C; 0.5-2.0 ml/mmHg) covering the human pathophysiological range. E(a), E(a)/E(max,) LV stroke work, and hydraulic power were calculated for all conditions. Multiple-linear regression analysis revealed a linear relation between E(a), R/T (where T is cycle length), and 1/C: E(a) = -0.13 + 1.02R/T + 0.31/C, indicating that R/T contributes about three times more to E(a) than arterial stiffness (1/C). It is demonstrated that different pathophysiological combinations of R and C may lead to the same E(a) and E(a)/E(max) but can result in differences of 10% in stroke work and 50% in maximal power.
Segers
Patrick
P
Hydraulics Laboratory, Institute of Biomedical Technology, Ghent University, B-9000 Gent, Belgium. patrick.segers@navier.rug.ac.be
Stergiopulos
Nikos
N
Westerhof
Nico
N
D001011:Aorta / Q000502:physiology; D001158:Arteries / Q000502:physiology*; D004548:Elasticity; D006801:Humans; D008955:Models, Cardiovascular; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology; D013599:Systole; D016277:Ventricular Function, Left / Q000502:physiology