Baroreflex sensitivity in children, adolescents, and young adults with essential and white-coat hypertension.

UNLABELLED: Hypertension, which is a common cardiovascular disease in adults, could originate in childhood. The aim of the study was to show differences in baroreflex sensitivity and short-term blood-pressure variability between healthy and hypertensive children, adolescents and young adults, and those with white-coat effect with respect to obesity. We examined 54 subjects (11-21 years) who had repeatedly high causal blood pressure. Basing on 24-hour blood pressure monitoring, the subjects were divided into groups: 24 subjects with hypertension (Hy) and 30 subjects with white-coat effect (WhC). Hy and WhC subjects were compared with age-matched healthy controls in a ratio of 1 : 2 for both groups: 48 controls for hypertensive subjects (CoHy) and 60 for subjects with white-coat effect (CoWhC). Totally, 162 subjects were studied. Systolic blood pressure (SBP) and inter-beat intervals (IBI) were recorded in all subjects for 5 min (Finapres, metronome controlled breathing at a frequency of 0.33 Hz). The power spectra of SBP and IBI were calculated. Indices of baroreflex sensitivity (BRS [ms/mmHg] and BRSf [mHz/mmHg]) were determined by the cross-spectral method. The SBP variability was determined as SBP spectral power in the range of 10-second rhythm (SBP (0.1Hz)). The body mass index (BMI) was significantly higher in both Hy and WhC compared with their controls (Hy vs. CoHy; WhC vs. CoWhC: 24.6 +/- 6.0 kg/m (2) vs. 20.4 +/- 2.8 kg/m (2), p < 0.001; 23.2 +/- 5.9 kg/m (2) vs. 20.3 +/- 2.6 kg/m (2), p < 0.05). BRS was significantly decreased in both groups (Hy vs. CoHy; WhC vs. CoWhC: 6.0 +/- 2.7 ms/mmHg vs. 9.5 +/- 3.9 ms/mmHg, p < 0.001; 7.2 +/- 3.1 ms/mmHg vs. 10.9 +/- 6.2 ms/mmHg, p < 0.01), and BRSf as well (Hy vs. CoHy; WhC vs. CoWhC: 10.8 +/- 4.6 mHz/mmHg vs. 16.2 +/- 6.1 mHz/mmHg, p < 0.001; 13.0 +/- 4.9 mHz/mmHg vs. 18.3 +/- 8.7 mHz/mmHg, p < 0.01). The decrease of baroreflex sensitivity was linked with the increase in the variability of SBP (0.1Hz), which was significant in hypertensives only (Hy vs. CoHy; WhC vs. CoWhC: 142 +/- 96 mmHg (2)/Hz vs. 94 +/- 83 mmHg (2)/Hz, p < 0.01; 121 +/- 131 mmHg (2)/Hz vs. 107 +/- 98 mmHg (2)/Hz).

CONCLUSION: The mild increase of BMI was associated with white-coat effect and a BRS and BRSf decrease. The greater increase of BMI was associated with hypertension and a deeper BRS and BRSf decrease. This greater decrease of BRS and BRSf in hypertensives was linked with the increased SBP-variability.