English

Abstract

A wide spectrum of biological function is regulated by the cyclic changes in estrogen and progesterone levels during regular menstrual cycle. However limited literature is available concerning the relationship of these hormones and cardiac autonomic activity. In the present study, we hypothesize that there would be heart rate variability during different phases of menstrual cycle, which can be attributed to the effect of ovarian steroids on cardiovascular function in women. The aim of the study is to compare the cardiac autonomic activity in the different phases of menstrual cycle (Menstrual, follicular and luteal phases) using heart rate variability. The objective is to establish a physiological correlation between the cardiac autonomic activity and different phases of menstrual cycle. The study was conducted in 48 regularly menstruating young female, of age group 18-30yrs, in the Upgraded Department of Physiology, Osmania medical college, from December 2011 to August 2013, using LABCHART software provided by ADLABS. The power spectral analysis of HRV was used to calculate low frequency(LF), high frequency (HF) component and their ratio (LF/HF) during menstrual (2±1 days), follicular(11±1 day) and luteal phases (20±1day) from the first day of bleeding. Results showed a significant increase was noted in low frequency component in luteal phase compared to follicular phase (p=0.000), whereas, a tendency for increase in high frequency component was observed in follicular phase (p=0.004). Furthermore, LF/HF was significantly higher in luteal phase than in the follicular phase (p=0.000) indicating an increased sympathetic activity. The conclusion is regulation of autonomic tone is modified during menstrual cycle. The alteration in the Ovarian hormones alterations along the menstrual cycle are associated with corresponding significant changes in multiple neuro-humoral homeostatic mechanisms regulating the cardio- vascular system. 4 The general presence of functional sex steroid hormone receptors in the cardiovascular system is well established and their expression in both heart and blood vessels have been recognized for decades.5,6,7,8 Estrogen is also associated with lower levels of endothelin and decreased sensitivity to the vaso-constrictive effects of peptide. The presence of estrogen receptors in the heart, vascular smooth muscle and autonomic brain centers, suggest a possible involvement in the regulation of cardiovascular system. In the follicular phase, estrogen causes an up-regulation in the cardiovascular or myometrial adreno-receptor.