Spontaneous Extension Wave for In Vivo Assessment of Arterial Wall Anisotropy

Am J Physiol Heart Circ Physiol. 2021 May 7. doi: 10.1152/ajpheart.00756.2020. Online ahead of print.ABSTRACTAnother type of natural wave, traced from longitudinal wall motion and propagation along the artery, is unprecedentedly observed in our in vivo human carotid artery experiments. We coin it as extension wave (EW) and hypothesize that EW velocity (EWV) is associated with arterial longitudinal stiffness. The EW is thus assumed to complement the PW, whose velocity (PWV) is tracked from the radial wall displacement and linked to arterial circumferential stiffness through the Moens-Korteweg equation, as indicators for arterial mechanical anisotropy quantification by noninvasive high-frame-rate ultrasound. The relationship between directional arterial stiffnesses and the two natural wave speeds was investigated in wave theory, finite-element simulations based on isotropic and anisotropic arterial models, and in vivo human common carotid artery (N=10) experiments. Excellent agreement between the theory and simulations showed that EWV was 2.57 and 1.03 times higher than PWV in an isotropic and an anisotropic carotid artery model, respectively, while in vivo EWV was consistently lower than PWV in all 10 healthy human subjects. A strong linear correlation was substantiated in vivo between EWV and arterial longitudinal stiffness quantified by a well-validated vascular guided wave imaging technique (VGWI). We thereby proposed a novel index calculated as EWV2/PWV2 as an alternative ...
Source: American Journal of Physiology. Heart and Circulatory Physiology - Category: Physiology Authors: Source Type: research