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Cardiac chronotropism and sympathovagal balance in young women of reproductive age

Int J Biol Med Res. 2012; 3(4): 2313-2318  |  PDF File


Abstract AIMS: TO study the heart rate variability during different phases of the menstrual cycle in young women of reproductive age and to correlate these changes if any to the sympathovagal activity during the phases. METHODS: The study included 30 eumenorrheic, normal, normotensive, healthy young females aged 18-30 yrs having regular, normal menstrual cycles. The subjects were selected based on certain predetermined exclusion-inclusion criteria by taking a detailed clinical history. A set of autonomic function tests which determine heart rate variability were done in all the three phases of the menstrual cycle to assess sympathetic and parasympathetic functions. No controls of any kind (males or menopausal females) were included as the aim of the study was to compare heart rate variability among the three phases of a single menstrual cycle. RESULTS: Across the menstrual cycle there was heart rate variability, with higher values towards the luteal phase, when compared to the follicular phase. A statistically significant difference in the heart rate parameters; resting heart rate, 30:15 ratio, standing to lying ratio and expiratory and inspiratory ratio were found between the phases, with higher values towards the luteal phase. The results were obtained using ANOVA and student-t-test,to study the significance of study parameters on continous scale within each phases. CONCLUSION: There was a statistically significant heart rate variability during the three phases of the menstrual cycle, as observed by the increased sympathetic outflow in the luteal phase compared to the increased parasympathetic outflow in the follicular phase. This altered regulation of the autonomic tone during the normal, regular menstrual cycle can be attributed to the normal, regular, cyclic changes in the ovarian hormones in healthy young females.