Radial-digital pulse wave velocity: a noninvasive method for assessing stiffness of small conduit arteries

Pulse wave velocity (PWV) is used to evaluate regional stiffness of large and medium-sized arteries. Here, we examine the feasibility and reliability of radial-digital PWV (RD-PWV) as a measure of regional stiffness of small conduit arteries and its response to changes in hydrostatic pressure. In 29 healthy subjects, we used Complior Analyse piezoelectric probes to record arterial pulse wave at the radial artery and the tip of the index. We determined transit time by second-derivative and intersecting tangents using the device-embedded algorithms and in-house MATLAB-based analyses of only reliable waves and by numerical simulation using a one-dimensional (1-D) arterial tree model coupled with a heart model. Second-derivative RD-PWV was 4.68 ± 1.18, 4.69 ± 1.21, and 4.32 ± 1.19 m/s for device-embedded, MATLAB-based, and numerical simulation analyses, respectively. Intersecting-tangent RD-PWV was 4.73 ± 1.20, 4.45 ± 1.08, and 4.50 ± 0.84 m/s for device-embedded, MATLAB-based, and numerical simulation analyses, respectively. Intersession coefficients of variation were 7.0% ± 4.9% and 3.2% ± 1.9% (P = 0.04) for device-embedded and MATLAB-based second-derivative algorithms, respectively. In 15 subjects, we examined the response of RD-PWV to changes in local hydrostatic pressure by vertical displacement of the hand. For an increase of 10 mmHg in local hydrostatic pressure, RD-PWV increased by 0.28 m/s (95% confidence interval: 0.16-0.40; P < 0.001). This study shows that RD-PWV can be used for the noninvasive assessment of regional stiffness of small conduit arteries. This finding allows for an integrated approach for assessing arterial stiffness gradient from the aorta to medium-sized arteries and now to small conduit arteries.NEW & NOTEWORTHY The interaction between the stiffness of various arterial segments is important in understanding the behavior of pressure and flow waves along the arterial tree. In this article, we provide a novel and noninvasive method of assessing the regional stiffness of small conduit arteries using the same piezoelectric sensors used for determination of pulse wave velocity over large- and medium-sized arteries. This development allows for an integrated approach for studying arterial stiffness gradient.