Cyclical alteration in heart rate variability among young eumenorrheic women

Introduction: The female sex hormones are known to have a cardioprotective role in premenopausal women compared to postmenopausal women.1,2,5 The key hormone estrogen and progesterone shows a cyclical variation along the different phases of menstrual cycle. Parasympathetic activity via vagus is known to improve the cardiac function compared to sympathetic activity.3 Heart rate variability (HRV) is one of the sensitive and non-invasive method to record the cardiac autonomic activity.4 Thus we chose this study to assess how the female sex hormones affect autonomic activity on the heart during the phases of menstrual cycle. Aim: To assess the effect of cyclical alteration in female sex hormones on cardiac autonomic activity by HRV. Materials and Methods: After getting institutional ethics committee clearance, short term HRV (5 minutes) was recorded in fifty young female volunteers aged between 20-30 years within normal range of BMI and regular menstrual cycle in supine posture after 10 minutes rest using PHYSIO PAC PP4 Medicaid system Chandigarh in the autonomic function lab, Department of Physiology, Sri Venkateshwaraa Medical College Hospital and Research Center, Ariyur, Pondicherry. Statistical analysis was done using SPSS 17 version. Results: The sympathetic parameters like (low frequency domain) LF nu, LF/HF ratio was significantly increased in the premenstrual phase. The parasympathetic parameters like (high frequency domain) HF nu, TP (total power) were significantly increased in the proliferative phase of the menstrual cycle. Conclusion: Thus the cardioprotective role of female sex hormones in premenopausal women was more pronounced in the proliferative phase of menstrual cycle. Keywords: Heart rate variability, Cardioprotective, Premenstrual phase, Proliferative phase.