YI 2.5 Direct Measurement of Stiffness Index β of Superficial Arteries Without Blood Pressure Estimation

DOI

10.2991/artres.k.201209.013How to use a DOI?

Keywords

Specific-stiffness; force-ultrasound; beta vascular-age

Abstract

Background: Arterial stiffness index (β) is a clinically accepted vascular metric, calculated from arterial pressure and diameter obtained simultaneously from a single arterial site [1]. Hence, accurate measurement of β can only be performed on arteries where pressure can be recorded along with the diameter. We present a method to evaluate β from superficial arteries using arterial force (F) and diameter (D) waveforms, employing mathematical models (shown below) exploiting the non-linear pressure-diameter relationship [2], without requiring absolute pressure.

Methods: Pilot functionality assessment was performed on eight participants (24 ± 5 years). A custom-developed frequency-matched system, combining single-element ultrasound and force-sensing transducers, was used to measure D and F waveforms from the common carotid artery. A hemodynamic-loop was formed from these measures and optimised to eliminate viscous components, and evaluate the elastic stiffness index β. Traditional β-formula [2] yielded reference values for comparison.

fe(t)=fmx×(eβ(D(t)Dd−1)−1eβ(DsDd−1)−1)

f_e(t): Viscosity eliminated arterial force

f_mx: Maxima of viscosity eliminated arterial force

β : Stiffness index

D(t): Arterial diameter

D_s: Systolic diameter

D_d: Diastolic diameter

Results: The system captured high fidelity D and F waveforms, adequate for reliable β evaluation. Measured group-average β (4.7 ± 0.8) was concurrent with literature. The measured β values statistically agreed (LoA = ±0.83 and bias = –0.32; non-significant p > 0.05) and strongly correlated (r = 0.93, p < 0.001) with the reference values. Further, they exhibited acceptable beat-to-beat repeatability (variation <7%) and accuracy (RMSE = 0.53).

Conclusion: The proposed method demonstrated the functionality by estimating reliable carotid β. Its key advantage is the applicability to superficial arteries, especially from sites where direct pressure measurement is challenging. Further studies demonstrating its potential for clinical and research applications are underway.

Copyright

© 2020 Association for Research into Arterial Structure and Physiology. Publishing services by Atlantis Press International B.V.

Open Access

This is an open access article distributed under the CC BY-NC 4.0 license (http://creativecommons.org/licenses/by-nc/4.0/).

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TY  - JOUR
AU  - Rahul Manoj
AU  - P.M. Nabeel
AU  - Kiran V. Raj
AU  - Jayaraj Joseph
AU  - Mohanasankar Sivaprakasam
PY  - 2020
DA  - 2020/12/31
TI  - YI 2.5 Direct Measurement of Stiffness Index β of Superficial Arteries Without Blood Pressure Estimation
JO  - Artery Research
SP  - S18
EP  - S18
VL  - 26
IS  - Supplement 1
SN  - 1876-4401
UR  - https://doi.org/10.2991/artres.k.201209.013
DO  - 10.2991/artres.k.201209.013
ID  - Manoj2020
ER  -