Twenty-four-Hour Profile of Central Blood Pressure and Central-to-Peripheral Systolic Pressure Amplification

BACKGROUND The significant difference in central and peripheral blood pressure (BP) values has only recently been widely recognized. Ambulatory BP monitoring has been shown to have advantages over office BP measurements because ambulatory monitoring can provide important information not available when only office BP is measured. The aim of this study was to assess the 24-hour central systolic pressure (CSP) profile, CSP short-term variability, and 24-hour systolic pressure amplification profile. METHODS The study group comprised 50 hypertensive subjects and 50 normotensive subjects. All participants underwent 24-hour peripheral and central pressure monitoring. RESULTS CSP was lower than peripheral pressure levels during the day (124.1 +/- 15.7 mm Hg vs 133.9 +/- 16.3 mm Hg; P < 0.001) and night hours (114.4 +/- 14.5 mm Hg vs 121.5 +/- 15.2 mm Hg; P < 0.001). The CSP nocturnal fall was lower than the peripheral pressure fall in normotensive subjects as well as in hypertensive subjects. Although 24-hour systolic pressure amplification was similar in subjects with and without hypertension (9.2 +/- 3.1 mm Hg and 8.3 +/- 2.4 mm Hg; P = NS), it was significantly lower during the night than during the day in both groups. The nocturnal fall in systolic pressure amplification was correlated with the day-night difference in heart rate (r = 0.70; P < 0.001). CONCLUSIONS Central pressure differs significantly from peripheral pressure during regular daily activity as well as during night hours. Moreover, it appears that systolic pressure amplification varies throughout the 24-hour period and that the main factor determining nocturnal fall in systolic pressure amplification is nocturnal drop in the heart rate. More studies are required to demonstrate advantage of this novel technique over traditional pressure monitoring in clinical practice.