Heart rate asymmetry in altered parasympathetic nervous system activity

Heart rate asymmetry (HRA) was defined as a visible and quantifiable phenomenon in resting healthy people using Poincaré plot. In our pervious study, HRA has been defined considering geometry of the Poincaré plot to better estimate the HRA in healthy subjects. This study was designed to asses the changes in HRA using Poincaré plot during different phases of perturbation in parasympathetic activity. Parasympathetic perturbations were achieved by Atropine infusion and scopolamine administration phase apart from baseline (normal) phase. The redefined Guzik's index (GIp) was calculated for each subjects in each phase of the experiments. In baseline phase the heart rate variability (HRV) of 7 (out of 8) subjects were found asymmetric which reduced to 5 subjects during atropine infusion. In contrast all 8 subjects were found to be asymmetric during scopolamine administration phase. These findings suggest that screening of HRA changes with change in parasympathetic activity of autonomic nervous system.