Central and Brachial Pressures: Effects on Arterial Stiffness in Older Adults

Using brachial blood pressure (BP) as a surrogate for central BP when calculating carotid arterial stiffness (CAS) has not been studied in older adults.

Veterans (n = 180) age 60+ were recruited from Madison VA Hospital. Resting supine brachial and central BP (estimated from radial artery waveforms, Atcor Medical) were obtained. Right common carotid diameters were measured using ultrasound (Philips CX50, L12-3 transducer) after a transverse sweep to identify plaque presence to optimize longitudinal angle of approach free of plaque. CAS (Peterson's elastic modulus [PEM], Young's elastic modulus [YEM]) and distensibility coefficient (DC) were calculated using brachial and central BP. Differences in CAS were compared using paired Wilcoxon tests. Linear regression models evaluated associations with cardiovascular risk factors.

Participants were 70.4 (7.7) years old and 27.8% were female. Average brachial systolic BP was significantly higher than central (132.3 [18.6] mm Hg vs. 123.8 [17.7] mm Hg P < .001). Compared to brachial BP, using central BP to calculate stiffness measures resulted in significantly lower YEM and PEM and significantly higher DC (PEM: 480.6 [209.5] mm Hg vs. 378.3 [178.4] mm Hg; YEM: 2220.2 [926.6] mm Hg vs. 1746.9 [785.4] mm Hg; DC: 2.4 [1.0] × 10-3 mm Hg-1 vs. 3.1 [1.1] × 10-3 mm Hg-1; all P < .001). Absence of hypertension was associated with smaller differences in PEM (β = -26.02, SE = 12.37, P = .04), while older age was associated with greater differences in DC when calculated using brachial vs. central BP (β  = 2.09 × 10-5, SE = 0.67 × 10-5, P = .002).

Brachial and central BP differ in older adults and result in significant differences in calculated CAS and distensibility. Brachial BP overestimates CAS, especially in hypertensive adults.