UCL logo

UCL Discovery

UCL home » Library Services » Electronic resources » UCL Discovery

Limitations of Augmentation Index in the Assessment of Wave Reflection in Normotensive Healthy Individuals

Hughes, AD; Park, C; Davies, J; Francis, D; McG Thom, SA; Mayet, J; Parker, KH; (2013) Limitations of Augmentation Index in the Assessment of Wave Reflection in Normotensive Healthy Individuals. PLoS One , 8 (3) , Article e59371. 10.1371/journal.pone.0059371. Green open access

[img]
Preview
PDF
journal.pone.0059371.pdf

Download (704kB)

Abstract

Objectives Augmentation index (AIx) is widely used as a measure of wave reflection. We compared the relationship between AIx and age, height and sex with ‘gold standard’ measures of wave reflection derived from measurements of pressure and flow to establish how well AIx measures wave reflection. Materials and Methods Measurements of carotid pressure and flow velocity were made in the carotid artery of 65 healthy normotensive individuals (age 21–78 yr; 43 male) and pulse wave analysis, wave intensity analysis and wave separation was performed; waveforms were classified into type A, B or C. AIx, the time of the first shoulder (Ts), wave reflection index (WRI) and the ratio of backward to forward pressure (Pb/Pf) were calculated. Results AIx did not correlate with log WRI or Pb/Pf. When AIx was restricted to positive values AIx and log WRI were positively correlated (r = 0.33; p = 0.04). In contrast log WRI and Pb/Pf were closely correlated (r = 0.66; p<0.001). There was no correlation between the Ts and the timing of Pb or the reflected wave identified by wave intensity analysis. Wave intensity analysis showed that the morphology of type C waveforms (negative AIx) was principally due to a forward travelling (re-reflected) decompression wave in mid-systole. AIx correlated positively with age, inversely with height and was higher in women. In contrast log WRI and Pb/Pf showed negative associations with age, were unrelated to height and did not differ significantly by gender. Conclusions AIx has serious limitations as a measure of wave reflection. Negative AIx values derived from Type C waves should not be used as estimates of wave reflection magnitude.

Type: Article
Title: Limitations of Augmentation Index in the Assessment of Wave Reflection in Normotensive Healthy Individuals
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1371/journal.pone.0059371
Publisher version: http://dx.doi.org/10.1371/journal.pone.0059371
Language: English
Additional information: © 2013 Hughes et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. PMCID: PMC3609862
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Pop Health Sciences > Institute of Cardiovascular Science
URI: http://discovery.ucl.ac.uk/id/eprint/1407130
Downloads since deposit
84Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item