Day-night pattern of autonomic nervous system modulation in patients with heart failure with and without sleep apnea.
BACKGROUND
Among patients with congestive heart failure (CHF) both obstructive and central sleep apnea (SA) are associated with increased sympathetic activity. However, the day-night pattern of cardiac autonomic nervous system modulation in CHF patients with and without sleep apnea is unknown.


METHODS
Twenty-five CHF patients underwent polysomnography with simultaneous beat-to-beat blood pressure (Portapres), respiration and electrocardiogram monitoring. Patients were divided according to the presence (SA, n=17) and absence of SA (NoSA, n=8). Power spectral analyses of heart rate variability (HRV) and spontaneous baroreflex sensitivity (BRS) were determined in periods with stable breathing while awake at 6 am, 10 am, 10 pm, as well as during stage 2 sleep. In addition, muscle sympathetic nerve activity (MSNA) was evaluated at 10 am.


RESULTS
RR variance, low-frequency (LF), high-frequency (HF) powers of HRV, and BRS were significantly lower in patients with SA compared with NoSA in all periods. HF power, a marker of vagal activity, increased during sleep in patients with NoSA but in contrast did not change across the 24-hour period in patients with SA. MSNA was significantly higher in patients with SA compared with NoSA. RR variance, LF and HF powers correlated inversely with simultaneous MSNA (r=-0.64, -0.61, and -0.61 respectively; P<0.01).


CONCLUSIONS
Patients with CHF and SA present a reduced and blunted cardiac autonomic modulation across the 24-hour period. These findings may help to explain the increased cardiovascular risk in patients with CHF and SA.
Ueno
Linda M
LM
School of Arts, Sciences and Humanities, University of São Paulo, São Paulo, Brazil. lindabrz@usp.br
Drager
Luciano F
LF
Rodrigues
Ana C T
AC
Rondon
Maria U P B
MU
Mathias
Wilson
W
Krieger
Eduardo M
EM
Júnior
Rubens Fazan
RF
Negrão
Carlos E
CE
Lorenzi-Filho
Geraldo
G
D000328:Adult; D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006333:Heart Failure / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000379:methods; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000503:physiopathology*