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Background: To date, assessment of sleep quality has been performed using all-night polysomnography with no other options. The purpose of this study is to try to evaluate sleep quality with a new method accessible to outpatients with heart failure.Methods: All-night polysomnogaraphy (EEG) and electrocardiaography (ECG) were performed in 7 patients with heart failure and 8 patients with normal cardiac function. Five-minute data of all-night EEG and RR intervals were serially obtained by shifting the data range every 50 sec and subjected to spectral analysis to detect slow wave activity (SWA) and high-frequency components (RR-HF) of heart rate variability. The ultradian rhythms were extracted by applying wavelet analysis to the sequential changes of SWA and RR-HF.Results: In patients with normal cardiac function, the ultradian rhythms of SWA and RR-HF had a large amplitude (SWA: 51 ± 8 %, RR-HF: 49 ± 13 %) of oscillations during early sleeping periods. These ultradian rhythms were synchronized with a high squared coherence of 0.80 ± 0.08. In patients with heart failure, however, the ultradian rhythms of SWA and RR-HF were significantly attenuated in amplitude ( SWA, 39 ± 21 %,p

Purpose: Despite an increased attention to anemia as a potential aggravating factor for heart failure, it remains unclear whether there is a critical hemoglobin(Hb) level that worsens cardiac function and functional capacity in chronic heart failure(HF). This study was designed to define the threshold of risk for the relationship between anemia and worsening HF. Methods: In 113 patients with HF, we measured Hb and estimated the severity of HF from cardiac function and exercise tolerance. Correlation coefficients between Hb and brain natriuretic peptide(BNP) and between Hb and peak oxygen consumption(peak VO2) were determined at more than 25 different Hb levels while shifting the upper limit of Hb from the highest towards lower levels. The critical Hb threshold was defined by plotting the correlation coefficient against each upper limit of Hb. Results: Hb levels were related to older age, female, greater functional impairment and cardiac dysfunction, and higher BNP. There was a significant inverse relationship between Hb and BNP (r = −0.45, p < 0.01), while Hb correlated positively with peak VO2 (r = 0.44, p < 0.01). Analysis of multilevel correlation function clearly demonstrated that the threshold level of Hb below which the correlation coefficient rose substantially was 13 g/dl both in BNP and in peak VO2. [Conclusions] The present findings suggest that a Hb threshold of risk exists rather than a linear relationship between Hb and HF.