Apnea-related heart rate variability in congestive heart failure patients.

Sleep-disordered breathing (SDB) causes fluctuation of the RR interval. However, the details are uncertain. We studied the characteristics of sleep-related heart rate variation (HRV) in congestive heart failure (CHF) patients with SDB. Ambulatory electrocardiograms and data on respiration (oronasal flow, trachea sound, abdominal wall movement, and oxygen saturation) were simultaneously recorded by a multi-channel digital recorder for 13 CHF patients (8 men and 5 women; mean age, 68 +/- 4 years). Heart rate variation occurred as a result of cyclical apnea attacks between 0.005 and 0.03 Hz (apnea band). The proportion of the apnea band (% apnea) increased with the number of apnea episodes, and SDB was highly likely when the % apnea was > or = 80%. Low-flow oxygen administration effectively reduced apnea frequency, and the apnea-related HRV also decreased. We concluded that apnea-related HRV was useful for detecting and following SDB in CHF cases.

Apnea-related heart rate variability and its clinical utility in congestive heart failure outpatients.

BACKGROUND: Cheyne-Stokes breathing (CSB) is an abnormal cyclical pattern of respiratory fluctuations observed during sleep in congestive heart failure (CHF) of poor prognosis. We examined the clinical usefulness of CSB screening using the heart rate variability (HRV) data from the ambulatory electrocardiogram. METHODS: We monitored ambulatory electrocardiograms and respiration simultaneously in 86 heart disease patients of both sexes, aged 57 +/- 1 years. HRV was analyzed by the maximum entropy method during the sleeping period (11 PM-5 AM). The 43 CHF patients underwent a 1-year follow-up study. RESULTS: In the power spectra of the HRV, peaks were observed within the CSB band (0.005 to 0.03 Hz). Statistically significant differences in HRV were observed between CSB patients and CSB-free patients in very low frequency (VLF) (P = 0.04), VLF/total frequency (TF) (P = 0.02), CSB (P = 0.01), CSB/TF (P = 0.003), and CSB/VLF (P < 0.0001). Cardiac events occurred in 23% of patients, including cardiac death in two, and rehospitalization for aggravated CHF in eight. In a multivariate Cox regression analysis in which age, sex, ejection fraction, NYHA functional class, beta blocker use, and basic heart disease were included, absence of ACE inhibitor use (RR 5.5, 95% CI 1.0-31) and CSB/VLF > or =80% (RR 4.2, 95% CI 1.1-17) remained significant predictors of cardiac events. CONCLUSIONS: HRV can act as an indicator of the presence of CSB in CHF patients, and could therefore be used, under outpatient conditions, to identify a CHF patients with a poor prognosis.