Comparison of cardiac autonomic activity between malnourished and healthy children

Severe malnutrition can significantly compromise autonomic nervous system. However, less is known about the cardiac autonomic activity in mild and moderate grades of malnutrition in children. Therefore, the objective of this study was to assess the effect of mild/moderate malnutrition on heart rate variability (HRV), a non invasive tool to estimate the cardiac autonomic activity. A cross sectional, community based study was conducted in which 35 malnourished children (mean age: 6.06 +/- 2.04 yrs), on the basis of anthropometric parameters, were enrolled in the study group by random samplings, who were the children of urban slum dwellers and 35 age and sex matched healthy children, were taken as controls. Grading of malnutrition was done according to Indian Academy of Pediatrics (IAP) classification. Anthropometry, basal heart rate (BHR), blood pressure were determined. Time domain and frequency domain indices of HRV were assessed using RMS Polyrite D (version 2.4). Weight, height, mid arm circumference (MAC) and body mass index (BMI) were found to be statistically lower in the study group. There was a strong negative correlation between MAC and LF component (P < 0.01). BHR was found to be increased in the malnourished group (P = 0.027). Low frequency (LFnu) & LF-HF ratio were found to be increased (P = 0.000 & P = 0.001 respectively) while high frequency (HFnu) component was decreased (P = 0.000) in malnourished group. Our results suggested that impaired cardiac autonomic nerve function characterized by sympathetic over activity may occur in malnourished children. This study also enables us to compare, in future works, HRV in pediatric subjects with different grades of malnutrition.