Abstract
Aging is associated with increased central aortic systolic pressure (CSP) and pulse pressure which are predictive of cardiovascular events. Mechanisms implicated for higher central pressures include a higher forward incident pressure wave (P1), higher augmented pressure (AP), and shorter reflected wave round trip travel time (Tr). African-Americans (AA) have more frequent and deleterious blood pressure elevation. Using applanation tonometry, we studied the association of age and CSP with P1 and AP in 900 AA subjects. Data showed that in subjects ≤50 years old, CSP was mediated by AP but not P1 or Tr, whereas in those >50, CSP was mediated by both AP and P1 and to a lesser extent by Tr. Predictive models were significant (R 2 = 0.97) for both age groups. In conclusion, wave reflection is the primary determinant of CSP in younger AA, while in older subjects, CSP is mediated by both the magnitude and timing of wave reflection as well as aortic impedance.
Highlights
Vascular aging and remodeling predominantly affects the large elastic arteries, with the unfavorable consequence of increased aortic stiffness and higher central systolic (CSP) and pulse pressure (PP) [1]
Mediation analysis demonstrated in younger subjects that central aortic systolic pressure (CSP) was mediated by augmented pressure (AP) (B = 0.07, 95% CI = 0.01 − 0.14, P < 0.05), but not by incident pressure (P1) or the reflected wave (Tr) (B = −0.001, 95% CI = −0.036–0.027, P = NS and B = −0.008, 95% CI = −0.03–0.0001, P = NS, resp.)
In subjects >50, the CSP was mediated by AP and P1 (B = 0.16, 95% CI = 0.11–0.25, P < 0.05 and B = 0.17, 95% CI = 0.09–0.22, P < 0.05, resp.), and to a lesser extent by Tr (B = −0.01, 95% CI = −0.03– −0.002, P < 0.05)
Summary
Vascular aging and remodeling predominantly affects the large elastic arteries, with the unfavorable consequence of increased aortic stiffness and higher central systolic (CSP) and pulse pressure (PP) [1]. It has been demonstrated that central pressures are more closely related to cardiovascular outcomes as compared to peripheral pressures [2]. Several mechanisms have been proposed for the higher central pressures observed with aging. Greater AP due to increased wave reflection is the conventional explanation of why CSP increases with age, with age-related increases in aortic stiffness shortening Tr and causing the reflected wave to sum on the incident wave during systole [4,5,6,7,8]. The reasons for higher CSP and PP with advancing age have not been fully clarified
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