Abstract P295: Ambulatory Blood Pressure And Heart Rate Variability In Dietary Sodium And Weight Intervention

Blood pressure (BP) fluctuates due to complex interactions between genetic factors and environmental stimulation. BP variability (BPV) is a physiological phenomenon, as a measure of hemodynamic conditions reflected in the autonomic nervous system. Daily (circadian) rhythms as biological time structures are considered essential parameters for recognizing and treating BP risk factors. Thus, ambulatory BP and heart rate (HR) were monitored (ABPM) in 11 normotensive (NT) in a free living, and 13 borderline hypertensive (BH) adults with Na and weight (WT, Kg) interventions in a freely moving lab environments, around the clock at 30-minute to hourly intervals. In the intervention study, circadian BP, HR, urinary aldosterone (Aldo, μg/h), creatinine (Cr), Na, K in mEq/h and Na/K ratio were compared. Data was analyzed by the linear least square rhythmometry method. All subjects showed significant circadian fluctuations in BP (mm Hg) and HR (beats/min). The circadian response peaked in the noon to late afternoon hours in the NT and in the reference stage of the intervention study. In NT, SBP: 111±2 with variability 14.6% and peak hr at 16:00; DBP: 74.0±1 with variability 16.0% and peak hr at 15:40; and HR: 64.3±2 with peak hr at 16:96 (-254°). In the intervention study with reference (I), Na restriction (II) and weight (WT) reduction (III) stages, SBP: 130±3.7; 130±1.7; 116±1.7 with variability (SBPV), 27.5, 31.4, and 25.4%; peak hrs at 16:26, 13:52; 12:24, respectively; DBP: 85±2.3; 83±2.2; 77±1.9 with variability (DBPV), 21.1, 26.4, 33.5%; peak hrs at 16:15, 18:29, 07:52, respectively; and HR: 64±2.1; 61±2.1; 66±2.3 with HRV, 30.2, 34.6, 28.3%; peak hrs at 15:07; 14:64, 14:55, respectively. Circadian UAldo: 0.63, 0.73, 0.58; UNa: 6.3, 2.9, 3.5; UK: 3.1, 3.1, 2.9; and WT: 89.9, 87.8, 83.2 in I, II, and III study stages, respectively. Thus, BP and HR, and their variabilities are the factors readjusted in the Na and WT reductions, and the peak shifted to earlier hours in the intervention. The variability, in the reference stage already higher than the NT levels, was not favorably changed with Na and WT interventions, although BP was normalized, especially following the WT reduction. Increased or shallow amplitudes may be predictive risk factors of vascular disease.