The effects of rate and irregularity on sympathetic nerve activity in human subjects.
Heart Rhythm
; 4(1): 20-6, 2007 Jan.
Article
em En
| MEDLINE
| ID: mdl-17198984
ABSTRACT
BACKGROUND:
We have recently shown that atrial fibrillation is associated with an increase in sympathetic nerve activity (SNA) compared with sinus rhythm. It remains unclear, however, whether these findings are true at various rates and whether the magnitude of sympathoexcitation is related to the degree of irregularity.OBJECTIVE:
To determine the role of irregularity in mediating the SNA changes at various pacing rates. Univariate analysis showed that as the irregularity increased, SBP increased (r = 0.44, P < .001) but that MAP and DBP did not change significantly.METHODS:
Using custom-made software, atrioventricular sequential pacing with predetermined rates (100, 120, and 140 bpm) and irregularities (standard deviation = 0%, 5%, 15%, and 25% of mean cycle length) was performed in 23 patients referred for electrophysiologic evaluation. Pacing at each rate/irregularity was performed for 2 minutes, with 2 minutes of recovery in between. Systolic, diastolic, and mean arterial blood pressure (SBP, DBP, and MAP), central venous pressure (CVP), and SNA were measured at baseline and during pacing.RESULTS:
Univariate analysis showed that as the irregularity increased, SBP increased (r = 0.44, P < .001 but that MAP and DBP did not change significantly. A significant correlation was found between the pacing irregularity and SNA, with greater sympathoexcitation noted at greater degrees of irregularity (r = 0.2, P = .04). A five-variable linear model using DBP, MAP, CVP, and degree of pacing irregularity to predict SNA was highly statistically significant (r = 0.46, P < .001). After controlling for hemodynamic changes, for every 1% increase in irregularity, there was a 6.1% increase in SNA.CONCLUSION:
We have shown that greater degrees of irregularity cause greater sympathoexcitation and that the effects of irregular pacing on SNA are independent of the hemodynamic changes.
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Fibrilação Atrial
/
Sistema Nervoso Simpático
/
Frequência Cardíaca
Tipo de estudo:
Prognostic_studies
Limite:
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article