Impairment of autonomic function induced by posture change in postmenopausal women

Blunted cardiac autonomic dynamics to active standing test in postmenopausal women

Introduction

Although both aging and menopause influence cardiovascular autonomic control, the effect of menopause per se remains unclear. The current study was undertaken to test the hypothesis that post-menopausal women (PMW) have a blunted cardiovascular autonomic adjustment to active standing compared to pre-menopausal women. Thus, we compared the heart rate variability (HRV) indexes from supine (SUP) to orthostatic (ORT) positions among young women (YW), young men (YM), older men (OM), and PMW.

Methods

The participants rested for 10 min in SUP and then stood up and remained for 5 min in ORT. ECG was continuously recorded, and R-R time series of about 300 beats were analyzed using linear (spectral analysis) and non-linear (symbolic analysis) methods. The variation from SUP to ORT was calculated (Δ = ORT-SUP) for each HRV index.

Results

In SUP, no difference was found for any HRV index among groups. However, Δ0V% and ΔLFn (cardiac sympathetic modulation) were reduced in PWM compared to all groups (OM, YW, and YM), while Δ2UV% and ΔHFn (cardiac vagal modulation) were reduced in PMW than the younger group (YW and YM). No differences were found among the male groups (OM and YM).

Discussion

In light of our results, the cardiac autonomic dynamic response to orthostatic stress is blunted in post-menopausal women compared to younger women and older men, a finding that might be influenced not only by aging.

Study of Comparison between Autonomic Dysfunction and Dyslipidemia in Healthy Postmenopausal Women

Background:

Obesity, physical inactivity, and altered estrogen levels play an important role in contributing to disease risk profile and autonomic dysfunction in healthy postmenopausal women. This study was conducted to test the correlation between autonomic dysfunction and dyslipidemia in healthy postmenopausal women.

Materials and Methods:

This study was carried out on sixty healthy postmenopausal women before the age of 65 years, without any gross systemic disease. The following five autonomic functional tests were performed on the study group: heart rate response to deep breathing, heart rate response to Valsalva maneuver, heart rate response to standing up from supine position, blood pressure response to sustained hand grip, and blood pressure response to standing up from supine position. Fasting lipid profile of the study group was tested.

Results and Conclusion:

In the present study, autonomic dysfunction was found in 67% of healthy postmenopausal women. Among the sixty female healthy postmenopausal women included in the study, 68% were found to have dyslipidemia. In our study, there is a statistically significant correlation between autonomic dysfunction and dyslipidemia in healthy postmenopausal women. In these healthy postmenopausal women with increased serum cholesterol, serum low-density lipoprotein, and serum triglycerides, there was autonomic dysfunction which is statistically significant. There is no statistical significance on comparing serum high-density lipoprotein cholesterol with autonomic dysfunction in healthy postmenopausal women.

Impact of endo- and exogenous estrogens on heart rate variability in women: a review

Measurement of heart rate variability (HRV) is an established method to assess the activity of the autonomic nervous system. The aim of this review was to examine the link between HRV, reproductive life stages and menopausal hormone therapy. A literature review was performed using the Medline database. Based on title and abstract, 45 studies were extracted out of 261 citations screened. Due to different study designs and evaluation methods, HRV indices were not directly comparable. Qualitative comparisons in between the vast majority of studies, however, demonstrated a decrease of the vagal dominance on the heart from the follicular to the luteal cycle phase, although some studies asserted no change. The intake of oral contraceptives appeared not to alter the vagal modulation of the heart. All investigations agreed on a decline of HRV towards higher sympathetic control after menopause. Different menopausal hormone therapy approaches showed a supporting impact of estrogen on HRV in most studies. A combined therapy of estrogen and progestogens revoked this benefit. Further research is needed to demonstrate how this process might be attenuated by different menopausal hormone therapies.