Figure 1.

A typical central aortic pressure waveform synthesized from the radial artery pressure waveform using applanation tonometry, with superimposed waveform of aortic blood flow. The dotted line is representative of the theoretical aortic pressure waveform independent of wave reflection. The line labeled flow is a representative waveform of aortic blood flow. Augmentation index is the ratio of augmented pressure (CSBP − P_i) and central aortic pulse pressure (CSBP − CDBP). Wasted left ventricular pressure energy is directly related to augmented pressure (CSBP − P_i) and to the time duration of the reflected aortic pressure wave, (ED − Δt_p). CSBP, central aortic systolic blood pressure; P_i, pressure at the first inflection point marking the onset of reflected aortic pressure wave return from the periphery; CDBP, central aortic diastolic blood pressure; Δt_p, round trip travel time of the reflected pressure wave to the major peripheral reflecting site and back to the aorta; Δt_r, systolic duration of the reflected aortic pressure wave; ED, ejection duration; ESP, end systolic pressure; LVE_W, wasted left ventricular pressure energy; AIx, augmentation index