Hemodynamic Correlates of Late Systolic Flow Velocity Augmentation in the Carotid Artery

Abstract

Background. The contour of the common carotid artery (CCA) blood flow velocity waveform changes with age; CCA flow velocity increases during late systole, and this may contribute to cerebrovascular disease. Late systolic flow velocity augmentation can be quantified using the flow augmentation index (FAIx). We examined hemodynamic correlates of FAIx to gain insight into determinants of CCA flow patterns. Methods. CCA Doppler ultrasound and wave intensity analysis (WIA) were used to assess regional hemodynamics in 18 young healthy men (age 22 ± 1 years). Forward waves (W 1) and backward waves (negative area, NA) were measured and used to calculate the reflection index (NA/W 1 = RIx). Additional parameters included W 2 which is a forward travelling expansion/decompression wave of myocardial origin that produces suction, CCA single-point pulse wave velocity (PWV) as a measure of arterial stiffness, and CCA pressure augmentation index (AIx). Results. Primary correlates of FAIx included W 2 (r = − 0.52, P < 0.05), logRIx (r = 0.56, P < 0.05), and AIx (r = 0.60, P < 0.05). FAIx was not associated with CCA stiffness (P > 0.05). Conclusions. FAIx is a complex ventricular-vascular coupling parameter that is associated with both increased expansion wave magnitude (increased suction from the left ventricle) and increased pressure from wave reflections.

Flow Velocity in Common Carotid Artery

“…VRI) and second systolic velocity compared with men (see Table 1). The augmentation of second systolic flow velocity in carotid artery was related to wave reflection arriving from the lower body or tho racic aorta [39]. The wave reflection in women was related to shorter body height that reflects shorter distance to reflecting site [2,3].…”

Hemodynamic relationship between ophthalmic artery and uterine artery in pre‐eclampsia: pulse wave reflection and transmission might provide the missing link

“…; figures 1 and 2, Heffernan et al. ). The timing corresponds to the systolic phase, preceding the appearance of the dicrotic notch.…”

“…We would like to share two preliminary observations. Firstly, in the OA Doppler waveform presented in figure S2 of the review 1 , the peak identified as 'first diastolic peak' (marked by a yellow arrow) actually represents a systolic P2, as known from other cerebrovascular Doppler waveforms (figure 9, Masuda et al 4 ; figure 1, Lockhart et al 9 ; figure 1, Hirata et al 10 ; figures 1 and 2, Curtis et al 11 ; figures 1 and 2, Heffernan et al 12 ). The timing corresponds to the systolic phase, preceding the appearance of the dicrotic notch.…”

“…UtA‐S is a waveform feature that is difficult to quantify. In contrast, OA‐P2 is visible in normal and pathological conditions and quantifiable throughout pregnancy (using for instance the peak ratio (PR) relative to the main systolic peak (P1) (PR = P2/P1), or the (cerebrovascular) flow augmentation index (FAIx = (P2 − ED)/(P1 − ED), where ED is end diastole,). Thus, in addition to the predictive value of OA Doppler for the development of early‐onset PE, as shown in the systematic review of Kalafat et al.…”

“…Reflection will increase with vasoconstriction and vascular tone and repetitive wave reflections along the systemic arterial tree (between cardiac level and body reflection sites) may occur 17,18 . PW reflection from the lower body seems to originate mainly in the pelvic region (body reflection 16,19 ) with secondary transmission to the cerebral circulation, thus generating an additional mid-systolic flow augmentation in cerebrovascular Doppler waveforms [10][11][12]20 . According to this model, the systolic P2 in the OA Doppler waveform (OA-P2) may be interpreted as a sign of PW reflection with secondary transmission to the cerebral circulation (Figure 1).…”