P.073 Integrated Arterial System Analysis in a Population of Healthy Middle-Aged Men and Women: Augmentation Index Versus Wave Reflection Indices

Abstract

Background

Age-induced alterations in arterial impedance and wave reflection contribute to elevated systolic and pulse pressure. Surrogate indices such as the augmentation index (AIx), suggest increased susceptibility for wave reflection in women.

Methods and Results

Carotid pressure and central flow waveforms were acquired non-invasively in 2132 apparently healthy subjects (1093 F/1039 M), aged between 35 and 55 at inclusion (a subgroup of the ‘Asklepios’ population). Input impedance, reflection coefficient |Γ₁| and the ratio of backward-to-forward pressure amplitude, P_b/P_f, both direct measures of wave reflection, were derived. AIx was assessed using (automated) identification of characteristic points on the pressure waveform, and the effective length of the arterial tree, L_eff , was calculated from the timing of the reflected wave and pulse wave velocity. In addition, we calculated AIx* and L_eff * where information from pressure and flow was used to obtain the timing of the reflected wave (through wave separation analysis). Both |Γ₁| (from 0.4143±0.0033 at age 38 to 0.4618±0.0048 at 54; mean±SEM) and P_b/P_f (0.4491±0.0033 to 0.5038±0.0044) increased with age (P < 0.001) without gender differences. AIx also increased with age, but was persistently higher in women (P < 0.001), while L_eff spuriously increased with age. Interestingly, while still increasing with age, there was virtually no gender difference in AIx* and L_eff* demonstrated the anticipated shift of reflection sites towards the heart.

Conclusion

With ageing, wave reflection increases to a similar degree in middle-aged healthy men and women. Analysis of wave reflection, using a modified AIx*, appears to yield more consistent results than conventional AIx.