Structural and load-dependent arterial stiffness across the adult life span.

Background: The arterial stiffening is attributed to the intrinsic structural stiffening and/or load-dependent stiffening by increased blood pressure (BP). The respective lifetime alterations and major determinants of the two components with normal aging are not clear.

Methods: A total of 3053 healthy adults (1922 women) aged 18-79 years were enrolled. The carotid intima-media thickness, diameter, and local BPs were automatically determined by the radio frequency ultrasound system. The Peterson and Young elastic moduli were then calculated to represent total arterial stiffness. Structural stiffness was recalculated at a reference BP of 120/80 mmHg with established models. Load-dependent stiffness was the difference between total and structural stiffness.

Results: Both structural and load-dependent stiffness increased with aging, with much larger changes in the structural components. The age-related increasing rates were higher in women for the structural stiffness than men (P < 0.05), but similar for the load-dependent stiffness. The clinical characteristics and arterial stiffness were widely correlated, but most correlations were quite weak (r < 0.3) other than BPs. Multiple regression analyses adjusted for sex, age and other clinical correlates showed that structural stiffness increased with pulse pressure (PP) and load-dependent stiffness increased with mean arterial pressure (MAP), respectively.

Conclusion: The age-related arterial stiffening is mainly caused by the intrinsic structural stiffening, which demonstrated significant age-sex interaction. BPs were the major clinical determinants of arterial stiffness, with PP and MAP associated with different arterial stiffness components. The differentiation of the structural and load-dependent arterial stiffness should be highlighted for the optimal vascular health management.