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Elevated augmentation index derived from peripheral arterial tonometry is associated with abnormal
Kevin S Heffernan1, Eshan A Patvardhan1, Michael Hession1
1The Vascular Function Study Group, Division of Cardiology, Tufts Medical Center, Molecular Cardiology Research Institute, Boston, MA, USA.
Clinical Physiology and Functional Imaging
|June 16, 2010
Summary
The augmentation index (AIx) measured by peripheral arterial tonometry (PAT) reflects ventricular-vascular coupling. Abnormal coupling, whether from arterial or ventricular changes, is linked to higher PAT-AIx values.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Vascular Diagnostics
Background:
- Augmentation index (AIx) is typically derived from arterial pressure waveforms.
- Peripheral arterial tonometry (PAT) allows AIx derivation from digital pulse volume waveforms.
- Physiologic correlates of PAT-derived AIx and ventricular-vascular coupling are not well understood.
Purpose of the Study:
- To investigate the relationship between AIx derived from PAT and measures of ventricular-vascular coupling.
- To explore the clinical utility of PAT-AIx in assessing cardiovascular load.
Main Methods:
- AIx was derived from pulse volume waves measured by PAT.
- Effective arterial elastance index (EaI) and left ventricular (LV) end-systolic elastance index (E(LV)I) were calculated using echocardiography.
- The ventricular-vascular coupling ratio was defined as EaI/E(LV)I.
Main Results:
- Patients were stratified into low, optimal, and high ventricular-vascular coupling groups.
- After adjusting for confounders, optimal coupling was associated with lower PAT-AIx (1 ± 4%).
- Conversely, low (13 ± 4%) and high (19 ± 5%) coupling groups exhibited significantly higher PAT-AIx.
Conclusions:
- Abnormal ventricular-vascular coupling, due to increased arterial or ventricular elastance, correlates with elevated PAT-AIx.
- PAT-AIx may serve as a non-invasive indicator of ventricular-vascular coupling.
- Further research is warranted to explore other vascular correlates of PAT-AIx.
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