Vol. 282, Issue 3, H1041-H1046, March 2002
Relation of effective arterial elastance to arterial system
properties
Patrick
Segers1,
Nikos
Stergiopulos2, and
Nico
Westerhof3
1 Hydraulics Laboratory, Institute of Biomedical Technology,
Ghent University, B-9000 Gent, Belgium; 2 Biomedical
Engineering Laboratory, Ecole Polytechnique
Fédéralé de Lausanne, Parc Scientifique d'Ecublens,
1015 Lausanne, Switzerland; and 3 Laboratory for Physiology,
Institute for Cardiovascular Research, Vrije Universiteit
University Medical Center, Amsterdam, The Netherlands
Effective arterial elastance
(Ea), 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 Emax, the slope of the LV end-systolic pressure-volume relation,
Ea/Emax 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
1 · s) and total arterial
compliance (C; 0.5-2.0 ml/mmHg) covering the human
pathophysiological range. Ea,
Ea/Emax, LV stroke work, and hydraulic power were calculated for all conditions. Multiple-linear regression analysis revealed a linear relation between
Ea, R/T (where
T is cycle length), and 1/C: Ea = 
0.13 + 1.02R/T + 0.31/C, indicating
that R/T contributes about three times more to
Ea than arterial stiffness (1/C). It is
demonstrated that different pathophysiological combinations of
R and C may lead to the same Ea and
Ea/Emax but can result in
differences of 10% in stroke work and 50% in maximal power.
arteries; heart-arterial coupling; arterial compliance; total
peripheral resistance; stroke work; maximal power
