PARALLEL CHANGE IN PERIPHERAL AND NONAUGMENTED CENTRAL PULSE PRESSURE WITH AGE

Abstract

Objective: Peripheral pulse pressure (PP) decreases in parallel to stroke volume during young adulthood, reaching a nadir in midlife. We postulate that during the same period, the progressive augmentation produced by wave reflection could overcome the effect of a decrease in forward pressure wave on central PP. The aim of the study was to evaluate the contribution of forward and backward pressure waves to the age related change in central PP and its expression at the brachial level. Design and method: This is a cross-sectional analysis of a cohort of 212 unmedicated hypertensive patients (16–93 years). Central PP (applanation tonometry of the radial pulse) and carotid-femoral pulse wave velocity (PWV) were assessed with a SphygmoCor device (operator index >70%). Central pressure waveform was calibrated with brachial SBP and DBP (OMRON 705). Augmentation pressure (AP) was calculated as the difference between the second and first systolic peaks. Forward pressure wave (nonaugmented central PP) was calculated as central PP - AP. Age was stratified in 3 groups: <30, 31–60 and >60 years. Comparisons were tested by ANOVA. Results: Peripheral PP showed two peaks, one before age 30 and another after age 60, with a nadir between 31–60 years (59 ± 15, 48 ± 10 mmHg and 58 ± 12 mmHg; in < 30, 31–60 and >60 years respectively; ANOVA <0.001). Forward pressure wave changed in parallel to peripheral PP, describing two peaks, one before 30 years and one after 60 years, and a nadir at 41–50 years (33 ± 8, 27 ± 6 and 32 ± 7 mmHg; in<30, 31–60 and >60 years respectively; ANOVA <0.001). In contrast, AP increased steadily with age (0.2 ± 5, 8 ± 6 and 15 ± 6 mmHg; in <30, 31–60 and >60 years respectively; ANOVA <0.001), in parallel to PWV (6.2 ± 1, 7.1 ± 1 and 8.7 ± 1.5 m/s, respectively; <0.001). As a result (figure), augmented central PP remained constant before increasing after age 60 (35 ± 7, 35 ± 8 and 47 ± 11 mmHg; at <30, 31–60 and >60 years respectively; ANOVA <0.001). Conclusions: Peripheral and nonaugmented central PP exhibited a parallel U shape relationship with age. The progressive increase in AP masked the nadir in forward pressure wave and minimized peripheral amplification.