Reactivity to low-flow in the brachial artery: A potential determinant for flow-mediated dilatory response
It is suggested that central augmented pressure (AP) and augmentation index (AIx) are due to wave reflection from peripheral to central arterial impedance mismatching. Comparatively stiffened peripheral vasculature should equate to increased AP and AIx. However, recent evidence suggests aortic reservoir characteristics may be a more dominant contributor to AP and AIx. This study aimed to determine relationship of central to peripheral impedance mismatch with, and predictors of, AP and AIx.
... f, AP and AIx. Methods: Carotid-to-femoral (aortic) pulse wave velocity (aPWV) and carotid-to-brachial PWV (bPWV) were measured in 255 patients with treated hypertension (aged 64AE8, 47% male). Central AP, AIx and aortic reservoir pressure were derived from radial tonometry. Participants were stratified according to 'high' (bPWV > aPWV, nZ64) or 'low impedance mismatch' (bPWV aPWV, nZ191). Results: Conflicting with theoretical expectations, central AP and AIx were significantly higher in participants with low-impedance mismatch compared to those with high-impedance (11AE6 vs 7AE6 mmHg, pZ0.001 and 24AE10 vs 21AE13 %, pZ0.05). Furthermore, impedance mismatch (bPWV-aPWV) was negatively and independently associated with AP (rZ0.-0.13, pZ0.04) and not associated with AIx (rZ0.-0.001, pZ0.99). However, aortic reservoir pressure was a positive independent predictor of AP and AIx (rZ0.80 and rZ0.62, p<0.001 for both). Conclusions: Contrary to prevailing theory, 'high-impedance' mismatch between central and peripheral arteries does not result in higher AP or AIx. Aortic reservoir characteristics, rather than discrete wave reflection from impedance mismatching between peripheral and central arteries, may better explain AP and AIx.