Analysis of heart period and arterial pressure variability in childhood hypertension : key role of baroreflex impairment

In adults, initial stages of hypertension are associated with elevated sympathetic drive and significant alterations in indirect autonomic markers. There is growing evidence that children in the highest-pressure percentiles will be more likely to develop hypertension in adulthood, although mechanisms are not understood. We assessed whether computer analysis of RR interval and arterial blood pressure variability could detect early autonomic alterations in childhood hypertension, as assessed by noninvasive time and frequency domain measures of baroreflex regulation. We studied 75 children, subdivided in 3 subgroups of similar age (9.7+/-0.2 years): control subjects, prehypertensive children (ie, children with arterial pressure values >90th and 95th percentile; systolic arterial pressure: 97+/-3/57+/-2, 121+/-5/70+/-1, and 128+/-2/80+/-2 mm Hg, respectively). We observed that hypertensive children demonstrate a significant impairment of the baroreflex as compared with control subjects (index alpha: 20+/-2 and 40+/-4 ms/mm Hg; spontaneous baroreflex slope: 20+/-2 and 37+/-5; ms/mm Hg; P