Granger causality analysis of baroreflex in obese children and adolescents

Background: Obesity is an important risk factor of arterial hypertension. The impairment of baroreflex - a principal blood pressure (BP) control mechanism - could contribute to the development of hypertension in obese patients. Previous studies have found a decreased baroreflex sensitivity (BRS) measured by transfer function analysis of spontaneous BP and heart rate (HR) oscillations in obese subjects. However, this method ignores the causality and directionality of HR and BP oscillations interactions. Aim: The aim of the study was to analyse BRS in obese normotensive children and adolescents using causal baroreflex analysis method. Methods: Continuous noninvasive recordings of BP (volume-clamp method) and R-R intervals (ECG) were obtained from 40 obese subjects (age: 14. 7±0.3 yrs, BMI: 32. 7±0.6 kg m^-2) and gender and age matched non-obese control subjects. Causal close loop model was used to measure classical (noncausal) BRS and causal feedback interaction from BP to HR (causal BRS). Results: The noncausal BRS did not show any significant difference between groups. On the other hand, causal BRS was lower (p = 0.030) in obese group. Conclusion: The causal BRS analysis is more sensitive in early detection of baroreflex impairment in obese children and adolescents compared to classical BRS method.