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
Artigo
em Inglês
| LILACS
| ID: lil-445663
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:
DisponíveL
Índice:
LILACS (Américas)
Assunto principal:
Sistema Nervoso Autônomo
/
Terapia de Reposição de Estrogênios
/
Pós-Menopausa
/
Estrogênios Conjugados (USP)
/
Coração
/
Frequência Cardíaca
Tipo de estudo:
Estudo observacional
/
Estudo de prevalência
/
Fatores de risco
Limite:
Adulto
/
Feminino
/
Humanos
Idioma:
Inglês
Revista:
Braz. j. med. biol. res
Assunto da revista:
Biologia
/
Medicina
Ano de publicação:
2007
Tipo de documento:
Artigo
/
Congresso e conferência
/
Documento de projeto
País de afiliação:
Brasil
Instituição/País de afiliação:
Universidade Estadual de Campinas/BR
/
Universidade Federal de São Carlos/BR
/
Universidade Metodista de Piracicaba/BR
/
Universidade de São Paulo/BR
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