Figure 1

Pulse wave analysis. The arterial pressure waveform is the sum of the forward wave following ventricular contraction and a backward wave reflected from the periphery. In vessels with normal elasticity, the wave velocity is sufficiently low to allow reflection of the backward wave at the aortic root during diastole. In the case of increased stiffness, velocity increases causing a premature reflection of the backward wave during systole. This phenomenon is quantified through the augmentation index (AIx)—defined as the difference between the second and first systolic peaks (P1-P2, absolute augmentation pressure) expressed as a percentage of the pulse pressure (P1-P3).