Kinetics of circadian variations in ambulatory arterial blood pressure and cardiovascular sequelae

Objective: to study the relationships between evolution of changes in blood pressure (BP) over the 24 hour cycle and their cardiac and vascular consequences in mild to moderate hypertensive (HT) subjects (WHO criteria). Material and methods: 151 patients presenting with mild to moderate essential HT (Age 49 ± 12 yrs, 63 M 44W) - ambulatory measurement of BP over 24 hours (Spacelabs 90207) automatic determination of the diurnal cycle by Fourier analysis (S harmonics) and calculation of the slope of BP variation (mmHg/hr) at the point of transition from day to night (nocturnal dip slope (NDS)), and at the change from night to day (morning rise slope (MRS). Patients with inversion of the day-night cycle were excluded, day-night being arbitrarily defined as 7 to 22h and 22 to 7h. Echography of left ventricular mass index (LVMI) / Penn convention, formula of Devereux, and carotido-femoral distensibility by pulse wave velocity (PWV, Complior Colson France). Results: ambulatory measures of BP and HR and of cardiovascular parameters were as follows. mmHg mmHg B/mn g/m m/sec mmHg/hr mmHg/hr 144.3 ± 14.9 92,1 ± 11,3 75 ± 10 106 ± 25 10.1 ± 2.0-10.0 ± 5.3 12.4 ± 5.2 The slope of nocturnal fall (NDS) and morning rise in SBP (MRS) is significantly correlated with LVMI (NDP r=-0.02, p=0.049, MPP r=0.21, p=0.029) and with PWV (MPP: r=0.32, p=0.005). No relationship was found with the DBP values. By multivariate analysis taking into account age, sex, 24h SBP. MPP slope velocity was the only variable which was significantly related with the model of PWV and LVMI (p<0.001). Conclusion: Dipper and non-dipper studies have been performed to examine the consequences of day night variations in BP. The evolution of diurnal changes in BP seems to have an effect on the vessels and heart and may be a simple analysis tool for assessing prognosis and therapeutic effects.