Response to Peripheral Augmentation Index and Wave Reflection in the Radial Artery
We thank Hughes et al1 for their helpful analysis of the relationship between the late systolic shoulder (SBP2) of the peripheral pulse and central systolic blood pressure. Their elegant wave intensity analysis gives a theoretical justification for using SBP2 to estimate central systolic blood pressure. A key remaining question is whether SBP2 accurately estimates central systolic blood pressure in young subjects in who direct invasive measurements are rarely obtained. Although there is no substitute for performing a comparison with invasive measurements where these are available, the analysis of Hughes et al1 provides an indirect means for cross-checking the validity of SBP2 by verifying that SBP2 coincides with a wave intensity close to 0. The analysis by Hughes et al,1 thus, not only provides insight into the physiological mechanisms contributing to peripheral amplification but the potential to explore the estimation of central systolic blood pressure from the peripheral pulse in a wider range of subjects than those undergoing cardiac catheterization.