Baroreflex sensitivity is reduced in obese normotensive children and adolescents

Abstract

Obesity is associated with autonomic nervous system dysfunction. The aim of the study was to evaluate baroreflex sensitivity, an indicator of autonomic nervous function, in 20 obese children and adolescents in comparison with 20 age- and sex-matched nonobese subjects. All subjects were examined in the supine position over a period of 50 min. Systolic blood pressure (SBP) and RR intervals were monitored continuously. Baroreflex sensitivity was assessed by cross-spectral analysis of SBP and RR interval oscillations (BRS index) and SBP and heart rate oscillations (BRSf index) within the low frequency range (0.04-0.15 Hz). Sensitivity was determined in 3 time intervals of 3 min each to evaluate changes during rest. The BRS index was significantly lower in obese children and adolescents than in the nonobese control group (p = 0.002). Significant changes in the BRS index over time (p = 0.004) were found only in nonobese subjects. In contrast, the BRSf index increased over time in both groups (p = 0.01), and no significant between-group difference was detected. In conclusion, obese children and adolescents show decreased resting baroreflex sensitivity with less variation compared with nonobese subjects. The BRS and BRSf indices appear to be only partially correlated.

Impaired autonomic function in normotensive obese children

“…This was in agreement with the observations made in adults, animals [19][20][21] and children [22]. One factor that could be responsible for this lower level of BRS is increased thickness of carotid wall [23].…”

The circadian pattern of cardiac autonomic modulation and obesity in adolescents

“…Lower HRV has been associated with CVD morbidity and mortality [5]. In recent years, several epidemiological studies have reported evidence of impaired CAM in obese children, finding a reduction of parasympathetic activity of HRV in the obese as compared to non-obese [6–10]. Nevertheless, previous findings from our group also demonstrated an impaired CAM towards a sympathetic overflow and reduced parasympathetic modulation in obese children [9].…”

Altered hemodynamic regulation and reflex control during exercise and recovery in obese boys

“…Yet, the mechanisms by which the excess weight is translated into hypertension remain unresolved. Increased resting blood pressure (BP) (36), reduced baroreceptor sensitivity (BRS) (24) and HR variability (HRV) (20) as well as decreased resting forearm blood flow have been reported from an early stage in obese children (37). However, the regulation of hemodynamic variables during sympathetic system activation, the role of muscle metaboreflex, and its interaction with arterial baroreflexes in the regulation of BP in childhood obesity have not been examined.…”