Central and Brachial Pressures: Effects on Arterial Stiffness in Older Adults
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Background
Using brachial blood pressure (BP) as a surrogate for central BP when calculating carotid arterial stiffness (CAS) has not been studied in older adults.
Methods
Veterans (n=180) age 65+ were recruited from Madison VA Hospital. Resting supine brachial BP and central BP (estimated from radial artery waveforms, Atcor Medical) were obtained. 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.
Results
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] mmHg vs 123.8 [17.7] mmHg p<0.001). 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] mmHg vs 378.3 [178.4] mmHg; YEM: 2220.2 [926.6] mmHg vs 1746.9 [785.4] mmHg; DC: 2.4 [1.0] x10 −3 mmHg −1 vs 3.1 [1.1] x10 −3 mmHg −1 ; all p<0.001). Absence of hypertension was associated with smaller differences in PEM and DC (PEM: β =−29.1, SE=12.1, p=0.02; DC: β =−123.8, SE=55.3, p=0.027), while older age was associated with greater differences in YEM when calculated using brachial vs central BP ( β =1.9×10 −5 , SE=0.69×10 −5 , p=0.006).
Conclusions
Brachial and central BP differ in older adults and result in significant differences in calculated CAS and distensibility. Brachial BP overestimates CAS, especially in those with hypertension.
