Cardiac Autonomic Modulation in Psychologically Stressed Subjects as Reflected by Heart Rate Variability

Abstract

Objective: To compare the frequency domain parameters of heart rate variability in stressed and non stressed subjects. Study Design: It was a cross sectional study. Place and Duration of Study: The study was conducted at Islamic International Medical College from June 2014 to December 2014. Materials and Methods: Eighty subjects between 20-40 years of age were inducted in the study after fulfilling DASS questionnaire and were divided into stress and control group. Ten minutes ECG of the subject was taken using power lab and analyzed for heart rate variability following the guidelines of Task Force of European Society of Cardiology and the North American Society of Pacing Electrophysiology. Frequency domain indices of heart rate variability were compared among stressed and control group using fast fourier transform. Results: Psychologically stressed subjects have significantly decreased high frequency in absolute unit and normalized unit (p<0.05) and increased low frequency in normalized unit and absolute unit (p< 0.05 and .001 respectively) and low to high frequency ratio when compared with controls (p<0.001). There was significant negative correlation among LF ms2 and HFms2(p<0.001, r = -423), LF ms2 and HFnu (p 0.001, r = -.386), HF ms2 and LFnu (p < 0.05, r=-.361) and HFms2 and LF/HF (p< 0.05, r=-,553),LF/HF and HFnu (p< .001 r=-,553), LFnu and HFnu (p< 0.05, r=-.237). There was also statistically significant positive correlation of LF/HF and LFnu (p <.001.r=.824). Conclusion: Assessment of Heart rate variability is an important measure of autonomic nervous system and effect of psychological stress on autonomic nervous system can be indexed by determining heart rate variability.