An Image-Free Ultrasound Device for Simultaneous Measurement of Local and Regional Arterial Stiffness Indices

The stiffness of large arteries, measured locally from a small segment or regionally over a long trajectory, has a highly clinically relevant role in cardiovascular hemodynamics. A comprehensive measure of vascular stiffness accounting for both the local and regional stiffness indices has strong potential in stratifying risks of future events. Existing technologies are not amenable for such combined measurements, especially with provisions for easy-to-use, minimal operator dependency, portability, and field deployability. In this work, we report a novel device with these features that perform simultaneous measurement of local and regional stiffness indices. The device uses a single-element ultrasound transducer to measure carotid diameter waveforms in an image-free manner. It estimates the carotid local stiffness indices such as stiffness index (β), pressure-strain elastic modulus (EP), and one-point local pulse wave velocity (PWVβ). A bladder-type thigh cuff enabled the synchronized acquisition of femoral pressure pulse wave, and was used to measure the carotid-femoral pulse wave velocity (cfPWV) – the gold-standard regional aortic stiffness index. An in-vivo study on 35 subjects verified the functionality and measurement reliability of the ARTSENS®. The measured beat-by-beat carotid β (range: 2.71 – 11.15), EP (range: 32.31 – 153.65 kPa), and PWVβ (range: 3.50 – 7.72 m/s) were repeatable with variability < 8.7%. The cfPWV measurements were in agreement with that provided by SphygmoCor device (R = 0.93, p < 0.001, and mean absolute error = 4.82%). The association between local and regional stiffness indices was further investigated. This study demonstrated a strong potential of using ARTSENS® to easily evaluate local and regional stiffness for screening in clinical and resource-constrained settings.