THE INFLUENCE OF SLEEP RELATED BREATHING DISORDERS TO HEART RATE VARIABILITY IN PATIENTS WITH HEART FAILURE
Background: Cardiac autonomic dysfunction related to heart failure (HF), may also be influenced by sleep related breathing disorders (SRBD). Aim was to evaluate the relationship between heart rate variability (HRV) and SRBD in patients(pts) with chronic HF.
Methods: 40 pts with HF (NYHA classII-III) were included. All pts underwent limited sleep study and they were divided into two groups according to apnea/hipopnea index (AHI).Group I with AHI 5/h and group II with AHI< 5/h. HRV was derived from 24h electrocardiogram and we used time domain variables and frequency domain analysis performed over entire 24h, as well as during the day and overnight.
Results: There were 19 pts in group I and 21pts in group II. Demographic characteristics and time domain variables did not differ among the groups.
Standard deviation of all normal RR intervals (SDNN); standard deviation of the average Frequency domain analysis: low frequency(LF), high frequency(HF),very low frequency(VLF) and the LF/HF over entire 24h and during daytime did not differ significantly between the groups. Group I had significantly impaired nocturnal LF/HF(p=0.005) but LF and HF were similar in both groups.
AHI significantly correlated with standard deviation of the average normal RR intervals for all 5-minute segments (SDANN)(r=-0.362,p=0.040) and the oxygen desaturation index exhibited a significant correlation with diurnal VLF (r=-.441, p=.040) and diurnal LF (r=.441,p=.040) Multivariate linear regression model revealed that AHI was independently associated with the SDANN (β=.651, p=.005) and diurnal VLF component (β=-.591, p=.010).
Conclusions: SRBD contribute significantly to alteration of HRV in pts suffering form chronic HF.