16 Original article Comparative Study of Heart Rate Variability in Normotensive And Hypertensive Individuals Dr. Rupali Parlewar, Dr. Barkha Rani * , Grant Government Medical College, Mumbai, Maharashtra. Correspondent authors Dr. Barkha Rani * , ABSTRACT Background - Hypertension is the most prevalent cardiovascular disorder that affects many organs of our body .Heart rate variability (HRV) is a simple, sensitive and non-invasive tool to monitor the cardiovascular function .The present study is for assessment of sympathovagal balance by analysing HRV in hypertensive individuals. Objectives - To analyse Heart Rate Variability (HRV) in normotensive and hypertensive individuals. Material and methods -30 hypertensive and 30 normotensive subjects between the age group of 30-60 years were selected. Lead-II ECG was recorded using instrument PHYSIOPAC-PP4, MEDICAID system, Chandigarh and HRV analysis was done using KUBIOS HRV analyser. Spectral indices of HRV based on frequency domain such as normalized low frequency power (LFnu), normalized high frequency power (HFnu), ratio of low frequency power to high frequency power (LF-HF ratio) and time domain such as standard deviation of normal-to-normal RR intervals (SDNN), root mean square successive difference (rMSSD) and the proportion of NN50 to the total number of NN intervals (pNN50) were assessed. Results- Our results showed LFnu (78.17±5.73) and LF-HF ratio(2.14±0.24) was significantly increased in hypertensives and significant decrease was seen in HFnu (37.13±3.70), SDNN (149.1±4.82), rMSSD (36.4±4.75)and pNN50 (9.97±1.90) in hypertensives by student’s paired t- test . Conclusion-Above result suggests increased sympathetic and decreased parasympathetic activity. The pathophysiology of hypertension is primarily due to an increase systemic vascular resistance. This is attributed to enhanced sympathetic activity leading to sympathovagal imbalance. Keywords- Hypertension (HTN), Heart Rate Variability (HRV),Time Domain Measures, Frequency Domain Measures. Author for correspondence- Dr Rupali Parlewar, Email ID - rupalifulzele@gmail.com