What do we know about the role of menopause in cardiovascular autonomic regulation in hypertensive women?

Objective: We investigated the systemic arterial hypertension effects on cardiovascular autonomic modulation and baroreflex sensitivity (BRS) in women with or without preserved ovarian function. Methods: A total of 120 women were allocated into two groups: middle-aged premenopausal women (42 +/- 3 y old; n = 60) and postmenopausal women (57 +/- 4 y old; n = 60). Each group was also divided into two smaller groups (n = 30): normotensive and hypertensive. We evaluated hemodynamic and anthropometric parameters, cardiorespiratory fitness, BRS, heart rate variability (HRV), and blood pressure variability. The effects of hypertension and menopause were assessed using a two-way analysis of variance. Post hoc comparisons were performed using the Student-Newman-Keuls test. Results: Comparing premenopausal groups, women with systemic arterial hypertension showed lower BRS (9.1 +/- 4.4 vs 13.4 +/- 4.2 ms/mm Hg, P < 0.001) and HRV total variance (1,451 +/- 955 vs 2,483 +/- 1,959 ms(2), P = 0.005) values than normotensive; however, the vagal predominance still remained. On the other hand, both postmenopausal groups showed an expressive reduction in BRS (8.3 +/- 4.2 vs 11.3 +/- 4.8 ms/mm Hg, P < 0.001) and HRV characterized by sympathetic modulation predominance (low-frequency oscillations; 56% +/- 17 vs 44% +/- 17, P < 0.001), in addition to a significant increase in blood pressure variability variance (28.4 +/- 14.9 vs 22.4 +/- 12.5 mm Hg-2, P = 0.015) compared with premenopausal groups. Comparing both postmenopausal groups, the hypertensive group had significantly lower values of HRV total variance (635 +/- 449 vs 2,053 +/- 1,720 ms(2), P < 0.001) and BRS (5.3 +/- 2.8 vs 11.3 +/- 3.2 ms/mm Hg) than the normotensive. Conclusions: Hypertensive middle-aged premenopausal women present HRV autonomic modulation impairment, but they still maintain a vagal predominance. After menopause, even normotensive women show sympathetic autonomic predominance, which may also be associated with aging. Furthermore, postmenopausal women with hypertension present even worse cardiac autonomic modulation.