Alteration of Heart Rate Variability in Patients of Depression.

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Altered cardiac autonomic functions in form of reduced Heart Rate Variability (HRV) have been found to be associated with increased cardiovascular morbidity and mortality in depressive patients. To investigate the relationship between HRV measures, which is a non-invasive marker of autonomic nervous system and depression. The study included a convenient sample size of drug naive depressive patients (n=30) diagnosed on basis of ICD-10 and compared with age and gender matched healthy volunteers (n=30). Five minute ECG recording was done for HRV analysis and frequency domain measures like LF (Low Frequency), HF (High Frequency), LF/HF ratio as well as time domain measures like SDNN (Standard Deviation of all NN interval) and RMSSD (Root Mean Square of Successive differences of NN intervals) were obtained. In the frequency domain parameters, values of LF (nu) and LF/HF Ratio were found to be significantly higher (p<0.001) whereas, that of HF (nu) was significantly lower (p<0.001) in depression group as compared to control group. However, in the time domain parameters, no significant difference was observed in SDNN and RMSSD values in between the two groups. HRV recordings showed significant changes in frequency domain parameters in the patients suffering from depression. Thus, it could be said from our study that autonomic imbalance reflecting enhanced sympathetic activation relative to parasympathetic component is associated with depression.