Vascular Aging Entails Arterial Dilatation in Addition to Increased Arterial Stiffness

Abstract

Introduction: The increase in arterial blood pressure occurring with aging is considered an important risk factor for end-organ damage in, among others, the brain. How exactly this risk emerges is largely unknown. Methods: We investigated the effect of aging on middle cerebral flow velocity (MCAFV) and noninvasive arterial blood pressure (NIBP) in 105 healthy volunteers aged 18 to 82 years. Both pulsatile signals were analyzed determining the first (Sys1) and second systolic peak (Sys2) and the diastolic flow velocity 560 ms after stroke onset (D560). Results: For NIBP, a linear increase was found with aging for Sys2 and D560 (0.72 and 0.14 mm Hg/year, respectively) but not for Sys1. For MCAFV, a linear decrease was found with aging for all variables, being more rapid for Sys1 than for Sys2 or D560 (−0.94, −0.41, and −0.54 cm/s/year, respectively). Both signals change from Sys1 dominant in young adults to increasingly Sys2 dominant in the elderly. Discussion: That MCAFV decreases with aging, whereas NIBP increases can best be explained by assuming arterial dilatation. Apart from the generally accepted increase in arterial stiffness, arterial dilatation may be an important additional factor in vascular aging: the loss of elastin allows arteries to dilate until restricted by arterial collagen. Conclusion: Normal values collected in this study support protocols for non-invasive monitoring that require a correction for age.