Circadian changes in blood pressure in the brachial artery and the aorta assessed by simultaneous monitoringin untreated hypertension

Objective. To study and compare the daily changes of parameters of central pulse wave (PW) with the traditional indicators of 24‑hour ambulatory blood pressure monitoring (ABPM) on the brachial artery (BA) depending on daily profile in different age groups.

Design and methods. Successful ABPM of brachial and central BP (> 85 % valid readings) was performed by oscillometric BPLab VASOTENS system (“Petr Telegin”, Nizhniy Novgorod, Russia) in 84 untreated hypertensive subjects (mean age 55,8 ± 9,6 years, male 36,9 %, clinical BP 152,6 ± 9,2 / 94,8 ± 8,2 mm Hg). The device allows to derive aortic BP and augmentation index (AIx) from brachial PW. Gender differences of central BP and AIx were evaluated in different age groups: < 55 (14 men, 23 women), 55–60 (7 men, 16 women), 61–70 years (10 men, 14 women). Differences were considered significant at p < 0,05.

Results. Nighttime central BP was disproportionately higher than daytime values, proven by a smaller difference between BP in BA and the aorta at night compared to daytime parameters. AIx@75 was higher at night than during day. The differences between systolic BP (SBP) and BP in BA and the aorta was 10,4 ± 2,2 and 11,4 ± 1,0 mmHg in daytime and lower at night — 8,1 ± 2,0 and 9,0 ± 1,8 mmHg. The number of non-dippers and night-pickers according to aortic SBP values was greater than according to SBP assessed in BA. Men had slightly higher levels of brachial and aortic SBP than women. More profound nocturnal decline of brachial and aortic SBP was found in in women than in men. Despite comparable heart rate, AIx@75 was higher in women at all time periods, however, nocturnal increase in AIx@75 was significantly more evident in men.

Conclusions.Central BP was disproportionately higher at nighttime than during the day, proven by a smaller difference between BP in BA and the aorta at night than during the day. AIx and its diurnal variation are characterized by gender-associated differences across all age group and are dependent on SBP daily profile. This finding should be considered when interpreting the results 24‑hour monitoring of central BP and requires

further investigation of its prognostic value.

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