Autonomic modulation of heart rate of young and postmenopausal women undergoing estrogen therapy
Braz. j. med. biol. res
; 40(4): 491-499, Apr. 2007. graf
Article
em En
| LILACS
| ID: lil-445663
Biblioteca responsável:
BR1.1
ABSTRACT
The aim of the present study was to determine whether estrogen therapy (ET) reduces alterations of the autonomic control of heart rate (HR) due to hypoestrogenism and aging. Thirteen young (24 ± 2.6 years), 10 postmenopausal (53 ± 4.6 years) undergoing ET (PM-ET), and 14 postmenopausal (56 ± 2.6 years) women not undergoing ET (PM) were studied. ET consisted of 0.625 mg/day conjugated equine estrogen. HR was recorded continuously for 8 min at rest in the supine and sitting positions. HR variability (HRV) was analyzed by time (SDNN and rMSSD indices) and frequency domain methods. Power spectral components are reported as normalized units (nu) at low (LF) and high (HF) frequencies, and as LF/HF ratio. Intergroup comparisons SDNN index was higher in young (median supine, 47 ms; sitting, 42 ms) than in PM-ET (33; 29 ms) and PM (31; 29 ms) women (P < 0.05). PM showed lower HFnu, higher LFnu and higher LF/HF ratio (supine 44, 56, 1.29; sitting 38, 62, 1.60) than the young group in the supine position (61, 39, 0.63) and the PM-ET group in the sitting position (57, 43, 0.75; P < 0.05). Intragroup comparisons HR was lower in the supine than in the sitting position for all groups (P < 0.05). The HRV decrease from the supine to the sitting position was significant only in the young group. These results suggest that HRV decreases during aging. ET seems to attenuate this process, promoting a reduction in sympathetic activity on the heart and contributing to the cardioprotective effect of estrogen hormones.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
LILACS
Assunto principal:
Sistema Nervoso Autônomo
/
Terapia de Reposição de Estrogênios
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Pós-Menopausa
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Estrogênios Conjugados (USP)
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Coração
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Frequência Cardíaca
Tipo de estudo:
Observational_studies
/
Prevalence_studies
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Risk_factors_studies
Limite:
Adult
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Female
/
Humans
Idioma:
En
Revista:
Braz. j. med. biol. res
Assunto da revista:
BIOLOGIA
/
MEDICINA
Ano de publicação:
2007
Tipo de documento:
Article
/
Congress and conference
/
Project document
País de afiliação:
Brasil
País de publicação:
Brasil