Abstract
Background: Autonomic responses are a sensitive indicator for assessing balance in sympatho-vagal system. Many studies have shown an increased response in the sympathetic system in post-menopausal women. Alteration in autonomic nerve function causes an increased incidence of hypertension, arrhythmias, or acute coronary syndrome. Thus, this study aims to find out the heart rate variability (HRV) among reproductive and post-menopausal women.

Aims and Objectives: The aim of the study was to compare the cardiovascular autonomic responses among reproductive and post-menopausal women.

Materials and Methods: This cross-sectional study was conducted in the department of physiology at government medical college, Kottayam on 40 reproductive and 40 post-menopausal women. Using PHYSIOPAC-PP4 (Medicaid Systems Chandigarh) machine, an electrocardiogram was recorded in both groups in the supine position for 5 min. The frequency and time domain data obtained were analyzed using SPSS software.

Results: The mean age group in reproductive women was 43 and post-menopausal women was 54. In the power spectrum analysis of HRV parameters the mean value of frequency domain Low frequency (LF) in reproductive women was 72.05 (S.D = 5.706) and post-menopausal women was 79.48 (S.D = 3.789). The high frequency (HF) in reproductive women was 28 (S.D = 5.588) and post-menopausal women were 20.53 (S.D = 3.789). The LF/HF ratio mean value obtained in reproductive women was 2.723 (S. D = 0.759) and post–menopausal was 3.992 (S.D 0.785). In the various time domain parameters, we estimated the mean value of the root mean square of successive differences (RMSSD) between normal heartbeats RMSSD and obtained the value in reproductive women as 25.05 (S.D = 11.88) and post-menopausal women as 12.68 (S.D = 5.535). The RR interval triangular index mean value in reproductive women was 0.0520 (S.D = 0.013) and post-menopausal women were 0.0345 (S.D = 0.01). In all these parameters, the P-value was found to be <0.001, so statistically highly significant.

Conclusion: In this study, higher values in time domain and frequency domain parameters for assessing sympathetic functions were seen in postmenopausal women when compared to women of the reproductive age group which was statistically significant. This may be due to age and hormonal influences. The power spectrum analysis of HRV parameters was proved to be a noninvasive method to assess the sympathovagal balance in the study group of women.

Key words: Heart Rate Variability; Reproductive Women; Post-menopausal Women; Autonomic Functions; Time Domain; Frequency Domain