Figure 1: Sample ensemble-averaged radial pressure waveform. Systolic augmentation index (sAIx) was calculated as the ratio of amplitude of the late systolic shoulder () the primary wave pressure peak () expressed as a percentage (). Diastolic augmentation index (dAIx) was calculated as . is the peak diastolic pressure in diastole associated with the dicrotic notch. corresponds to a point on a straight line passing through the onset of the incisura of the dicrotic notch and tangential to the natural monoexponential decay of the late diastolic waveform. / was taken as the slope (maximal first derivative) of the maximum rate of pressure rise in systolic pressure per unit time. The slope of the late diastolic decay (, tau) was calculated as the final two-thirds of the diastolic time interval/(lnESP − lnDP).