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Inadequacy of Augmentation Index for Monitoring Arterial Stiffness: Comparison with Arterial Compliance and Other Hemodynamic Variables

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Abstract

Purpose

Augmentation Index (AIx) is used clinically for monitoring both wave reflections and arterial stiffness, which when increased is a risk factor of cardiovascular mortality and morbidity. We hypothesize that AIx is not solely related to vascular stiffness as described by arterial compliance and other hemodynamic parameters since AIx underestimates wave reflections.

Methods

Aortic pressure and flow datasets (n = 42) from mongrel dogs were obtained from our experiments and Mendeley Data under various conditions. Arterial compliances based on the Windkessel model (Ct), the stroke volume (SV) to pulse pressure (PP) ratio (Cv = SV/PP), and at inflection pressure point (CPi) were computed. Other relevant hemodynamic factors are also computed.

Results

AIx was poorly associated with arterial stiffness calculated from Ct (r = 0.299, p = 0.058) or CPi (r = 0.203, p = 0.203), even when adjusted for heart rates. Ct and Cv were monotonically associated. Alterations in inflection pressure (Pi) did not follow the changes in pulse pressure (PP) (r = 0.475, p = 0.002), and Pi was quantitatively similar to systolic pressure (r = 0.940, p < 0.001).

Conclusion

AIx is neither linearly correlated with arterial stiffness, nor with arterial compliance and several cardiac and arterial parameters have to be considered when AIx is calculated.

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Author Contributions

All authors contributed to the study conception and design. All authors contributed to writing the manuscript and all authors read and approved the final manuscript.

Funding

This research did not receive any specific Grant from funding agencies in the public, commercial or not-for-profit sectors.

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All authors declare that they have no conflict of interest.

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All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. This article does not contain any studies with human participants performed by any of the authors.

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Authors and Affiliations

  1. Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, 150 W University Blvd, Melbourne, FL, 32901, USA

    Mehmet Kaya & Vignesh Balasubramanian

  2. Department of Biomedical Engineering and Robert Wood Johnson Medical School, Rutgers University, 599 Taylor Road, Piscataway, NJ, 08854, USA

    John K.-J. Li

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  1. Mehmet Kaya
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Correspondence to Mehmet Kaya.

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Kaya, M., Balasubramanian, V. & Li, J.KJ. Inadequacy of Augmentation Index for Monitoring Arterial Stiffness: Comparison with Arterial Compliance and Other Hemodynamic Variables. Cardiovasc Eng Tech 13, 590–602 (2022). https://doi.org/10.1007/s13239-021-00605-z

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