Absence of sympathetic overactivity in Afro-Caribbean hypertensive subjects studied by heart rate variability.
J Hum Hypertens
; 14(5): 337-42, 2000 May.
Article
em En
| MEDLINE
| ID: mdl-10822322
ABSTRACT
Black hypertensives present a greater prevalence of left ventricular hypertrophy and an increased mortality compared to white hypertensives. Differences in sympathetic activity might contribute to explain these racial differences in hypertension. Nevertheless, previous laboratory studies did not show any increase of sympathetic activity direct to the heart in black subjects. The aim of the present study was to investigate the cardiac sympatho-vagal balance in black and white hypertensives analysing heart rate variability, during the entire 24 h. We analysed Holter recordings of 52 essential hypertensive patients, who had never received antihypertensive treatment, 26 of whom were black and 26 were white. Consecutive series of 300 beats, with 150 beats overlapped (approximately 600 series/day), were considered for the analysis in time and frequency domain. The mean 24-h value of the power of the low frequency spectral component (0.04-0.15 Hz), expressed in normalised units, ie a marker of sympathetic modulation, was significantly lower in the group of black patients compared to whites (respectively 40.0 +/- 2.1 vs 53.6 +/- 3.6 nu, P < 0.01). Similar results were observed for the LF/HF ratio, an index of the sympatho-vagal balance (respectively 4.11 +/- 0.58 vs 5.98 +/- 0.79; P < 0.05). In a multiple linear regression analysis, considering diastolic blood pressure, left ventricular mass index, race and age as independent variables, only race (P < 0.002) and age (P < 0.01) could independently predict the normalised low frequency power or the LF/HF ratio, as dependent variables. The results of this study suggest some blunting of the cardiac sympathetic neural modulation in black hypertensives compared to white hypertensives, during the entire 24 h.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sistema Nervoso Simpático
/
População Negra
/
População Branca
/
Frequência Cardíaca
/
Hipertensão
Tipo de estudo:
Prognostic_studies
/
Risk_factors_studies
Limite:
Adult
/
Female
/
Humans
/
Male
/
Middle aged
País/Região como assunto:
Africa
Idioma:
En
Revista:
J Hum Hypertens
Assunto da revista:
ANGIOLOGIA
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Itália