Important differences between hypertensive middle-aged women and men in cardiovascular autonomic control—a critical appraisal

Abstract

Background Normotensive premenopausal women show a vagal predominance of cardiac autonomic modulation, whereas age-matched men show a predominance of sympathetic modulation. However, some women develop systemic arterial hypertension (SAH) even with preserved ovarian function. Our hypothesis is that these women may have cardiovascular autonomic parameters similar to those of hypertensive men, even when subjected to pharmacological treatment. We aimed to investigate cardiovascular autonomic control and baroreflex sensitivity (BRS) in hypertensive premenopausal women and age-matched men. Methods One hundred volunteers between 18 and 45 years of age were assigned to two groups (50 participants each): a hypertensive group including patients with a history of SAH for at least 6 months (25 men and 25 women), who were under treatment with monotherapy (losartan, 25–50 mg/kg); and a normotensive group (25 men and 25 women). Anthropometric, hemodynamic, metabolic, and autonomic cardiovascular assessments were performed focusing on BRS, autonomic modulation of heart rate variability (HRV), and blood pressure variability (BPV). Results On HRV analysis, women showed higher values of high-frequency (HF) oscillations in absolute and normalized units, lower values ​of low-frequency (LF) in normalized units, and lower LF/HF ratio, as compared with men. When the normotensive and hypertensive groups were compared, hypertensive groups showed lower values ​of total variance and of LF and HF bands in absolute units. On BRS, hypertensive groups showed lower values than the normotensive group. Conclusion Regardless of blood pressure control through pharmacological treatment, hypertensive patients continued to have reduced HRV compared to normotensive, and hypertensive men had more autonomic impairment than hypertensive premenopausal women.

Heart Rate Variability and Cardiovascular Fitness: What We Know so Far

“…In this case, HRV indices are important markers of an increased risk of cardiac events and sudden death in these individuals. 7,21,[26][27][28]…”

“…127,137 More recent studies have shown that women before menopause have lower oscillations of the sympathetic autonomic component and greater oscillations of the cardiac vagal autonomic component when compared to age-matched men (Figure 2), 69,70,138,139 including individuals with a history of systemic arterial hypertension. 26 The causes of these differences have not been fully elucidated; however, the beneficial effect of ovarian hormones on cardiovascular autonomic control is a very important variable, since estrogens seem to be able to increase the vagal influence on the heart, in addition to reducing the sympathetic influence on the heart and vascular beds. [140][141][142] These effects are consistent with other studies that observed autonomic impairments resulting from ovarian failure, such as a reduction in HRV and baroreflex sensitivity.…”

Physical exercise is essential for cardiac autonomic regulation in hypertensive patients treated with losartan or enalapril

“…The choice to include only men was based on previous studies, which showed that men and women have differences in cardiac autonomic modulation balance. In this case, the men had a greater predominance of the sympathetic autonomic component [22][23][24].…”

Role of aerobic physical training on cardiac autonomic and morphophysiological dysfunction in hypertensive rats subjected to ovarian hormone deprivation

“…Among these impairments, adverse cardiac morphological and functional adaptations and cardiovascular autonomic control changes are the most common and often associated with a less favorable prognosis ( 3 - 6 ). However, little is known about the contribution of ovarian hormones to autonomic and morphofunctional cardiac protection due to SAH.…”