The impact of geometry, intramural friction, and pressure on the antegrade longitudinal motion of the arterial wall: A phantom and finite element study

A comment on the physiological basis for longitudinal motion of the arterial wall

The longitudinal motion and the intramural shear strain of the arterial wall increase dramatically in response to blood pressure, thereby impacting the vascular wall microenvironment. Exposure to a sedentary lifestyle has been identified as an independent risk factor for cardiovascular disease, but it has been shown that intermittent physical activity embedded into everyday life is enough to improve cardiovascular health. Marked changes in longitudinal motion already at a low workload may explain this finding. However, to understand the mechanism linking longitudinal motion and cardiovascular health, an understanding of the physiological basis for the longitudinal motion of the arterial wall is needed. The factors underlying the longitudinal motion of the arterial wall in vivo are numerous and intertwined. As a comment and complement to the recent review by Athaide et al. (Am J Physiol Heart Circ Physiol 322: H689-H701, 2022), we propose and discuss a comprehensive cardiovascular mechanical scenario based on the current literature. In this scenario, blood pressure, typically acting in the radial direction, also acts directly in the longitudinal direction through a tapered geometry. This complements ventricular contraction, ventricular-vascular coupling, arterial diameter change, arterial stiffness in both the radial and longitudinal directions, and prestretch of the arterial wall. In addition, we consider the geometry of the arterial tree and intramural friction of the arterial wall. Together, these important cardiovascular mechanical factors form the pattern of longitudinal motion of the arterial wall, indicating that the longitudinal motion of the arterial wall is important for cardiovascular health.

The influence of physical activity and sex on carotid artery longitudinal wall motion in younger healthy adults

Carotid artery longitudinal wall motion (CALM) is a novel preclinical marker for atherosclerosis that describes the axial anterograde and retrograde motion of the intima-media complex. While regular physical activity and sex are known to independently influence arterial stiffness, their roles on axial arterial wall behaviour are unknown. The purpose of this study is to examine whether physical activity and sex impact CALM. We hypothesized that CALM retrograde displacement and total amplitude would be greater in females and active individuals, as a function of arterial stiffness. Fifty-seven young healthy adults (30 females; aged 22 ± 3 years) were evaluated for CALM outcomes and arterial stiffness and grouped by physical activity based on active (V̇O2 = 44.2 ± 8.9 mL/kg/min) or sedentary (V̇O2 = 33.7 ± 6.7 mL/kg/min) lifestyles defined by the Canadian 24-Hour Movement Guidelines. Arterial stiffness and CALM were measured by carotid-femoral pulse wave velocity (cfPWV) and vascular ultrasound at the right common carotid artery with speckle tracking analysis, respectively. cfPWV was greater in males (p < 0.01) with no interaction between sex and physical activity (p = 0.90). CALM anterograde displacement was greater in males (p = 0.03) resulting in a forward shift in total CALM pattern, which became less prominent when controlling for mean arterial pressure (p = 0.06). All other CALM outcomes were not different between activity and sex. V̇O2max was not correlated to any CALM outcome (all p > 0.05). Apparent sex differences in vascular function extend to novel CALM outcomes but may be confounded by blood pressure. We recommend sex-balanced design and reporting in future studies due to possible anterograde-shifted CALM patterns in healthy males.