Aortic input impedance in normal man: relationship to pressure wave forms.

Misinterpretation of the Determinants of Elevated Forward Wave Amplitude Inflates the Role of the Proximal Aorta

“…Rectified wave reflections result in the divergence of the forward wave morphology from that of aortic flow (and from the product of aortic flow×Zc), particularly in late systole and in diastole 16, 34, 38. This is evident in our dog (Figure 2), T‐tube modeling (Figure 3), and human studies (Figure 4), in which increased reflections resulted in a: (1) greater FWA relative to the product of peak flow and Z c ; (2) later peaking of the forward wave relative to peak flow; and (3) greater divergence in the morphology of the forward wave relative to product of flow and Z c , resulting in a greater difference in their pressure‐time integrals 7, 30. The fact that vasoactive stimulation (NTP, MTX), which primarily affects the distal circulation, caused variable timing to peaking of the forward wave relative to time of peak flow reveals that FWA is a much more complex parameter than simply peak flow interacting with Z c .…”

“…The input into the model was a measured ascending aortic flow waveform typical of (1) a young adult from the study of Murgo et al 30. and (2) an older adult from our human substudy.…”

Ascending fractional pulse pressure closely relating to large artery function

“…Ascending aortic pressure at inflection point dividing into an early and late systolic phase was used as inflection pressure [1][2][3] (Figure 1). The ascending aortic pressure waveform was divided into three subgroups (A, B and C) according to classification by Murgo et al [1][2][3] Augmentation index was characterised as the ratio of inflection pressure to pulse pressure in subgroup A and B, and as the ratio of minus inflection pressure to pulse pressure in subgroup C. Pulsatility was characterised as the ratio of pulse pressure to mean pressure, ie, the PPF of the artery.…”

“…The ascending aortic pressure waveform was divided into three subgroups (A, B and C) according to classification by Murgo et al [1][2][3] Augmentation index was characterised as the ratio of inflection pressure to pulse pressure in subgroup A and B, and as the ratio of minus inflection pressure to pulse pressure in subgroup C. Pulsatility was characterised as the ratio of pulse pressure to mean pressure, ie, the PPF of the artery. [4][5][6][7] Figure 1 Schematic representation of augmentation index and inflection time of ascending aortic artery in a representative case.…”

“…[1][2][3] Augmentation index is closely related to reflection in the arterial system and large artery function. Although augmentation index is an attractive tool to understand the arterial system, the analysis augmentation index is occasionally invalid using the fluid-filled recording system.…”