Effective Arterial Elastance Is Insensitive to Pulsatile Arterial Load

Effective arterial elastance (E A ) was proposed as a lumped parameter that incorporates pulsatile and resistive afterload and is increasingly being used in clinical studies. Theoretical modeling studies suggest that E A is minimally affected by pulsatile load, but little human data are available. We assessed the relationship between E A and arterial load determined noninvasively from central pressure–flow analyses among middle-aged adults in the general population (n=2367) and a diverse clinical population of older adults (n=193). In a separate study, we investigated the sensitivity of E A to changes in pulsatile load induced by isometric exercise (n=73). The combination of systemic vascular resistance and heart rate predicted 95.6% and 97.8% of the variability in E A among middle-aged and older adults, respectively. E A demonstrated a quasi-perfect linear relationship with the ratio of systemic vascular resistance/heart period (middle-aged adults, R =0.972; older adults, R =0.99; P A in either middle-aged or older adults. Despite pronounced changes in pulsatile load induced by isometric exercise, changes in E A were not independently associated with changes pulsatile load but were rather a nearly perfect linear function of the ratio of systemic vascular resistance/heart period ( R =0.99; P A is simply a function of systemic vascular resistance and heart rate and is negligibly influenced by (and insensitive to) changes in pulsatile afterload in humans. Its current interpretation as a lumped parameter of pulsatile and resistive afterload should thus be reassessed.