Arterial stiffness in the context of heart rate and vasomotion during orthostatic stress and cognitive load

Introduction Variability in cardiovascular parameters reflects complex interactions among regulatory mechanisms. Arterial stiffness, a key determinant of heart–vessel interaction and cardiac performance, is commonly assessed using pulse wave velocity, though its dependence on blood pressure limits interpretability. The Cardio-Ankle Vascular Index (CAVI), a widely used non-invasive measure of arterial stiffness, and its refined form CAVI 0 , aim to address this limitation. However, evidence suggests that these measurements may still be affected by factors such as vascular smooth muscle tone and heart rate. This study investigated the short-term effects of physiological stressors, including body position changes (considering hydrostatic pressure) and cognitive load on CAVI 0 , to better understand the influence of confounding factors on arterial stiffness assessment. Methods Twenty-three healthy adults (age 22.3 ± 2.4 years, 16 male) were recruited. CAVI 0 was measured using the VaSera VS-1500, with adjustments for blood pressure and hydrostatic effects (CAVI 0 ADJ ) during three randomized tilt sequences (10° head-down tilt (HDT), 20° head-up tilt (HUT), and 40° HUT) and a mental arithmetic (MA) task inducing cognitive load. Continuous ECG, volume clamp photoplethysmography, and impedance cardiography recordings were used to derive heart rate, blood pressure, cardiac output, and systemic vascular resistance. Results CAVI 0 ADJ increased progressively, showing significant elevations at 20° and 40° HUT versus supine and 10° HDT. Brachial mean blood pressure did not change across postural positions, whereas heart rate and systemic vascular resistance increased during upright postures. Changes in CAVI 0 ADJ positively correlated with heart rate (p < 0.001) and systemic vascular resistance (p = 0.040), but not with brachial mean blood pressure. During the MA task, brachial mean blood pressure, heart rate, and systemic vascular resistance all increased significantly, whereas CAVI 0 remained unchanged. Conclusion Our study shows that CAVI 0 is not influenced by acute blood pressure changes caused by moderate mental stress pointing towards its robustness against blood pressure alterations. During head-up tilt, CAVI 0 is influenced not only by hydrostatic pressure but also by heart rate and vasomotion, highlighting the importance of considering body position and autonomic responses when assessing arterial stiffness as an indicator of structural changes in arterial wall associated with atherosclerotic process.