RESUMO
OBJECTIVES: The physiological significance of diurnal fluctuations in heart rate variability (HRV) has not been established to a full extent. The aim of our investigation was to assess a new method of power spectrum analysis of circadian oscillations in HRV in patients with left ventricular systolic and diastolic dysfunction. METHODS: Holter ECG monitoring and echocardiography were performed in 101 patients with coronary artery disease and arterial hypertension: 55 patients with systolic left ventricular dysfunction (LVD) and 46 patients with diastolic LVD, and also in 32 subjects of the control group. The original method of HRV assessment was based on spectrum analysis of time series of consecutive 5-minute measures of standard deviations of mean RR intervals. RESULTS: The study revealed oscillations of HRV with a periodicity of 12 hours and 80-120 minutes. Their amplitude was highest in the control group and lowest in patients with systolic LVD. CONCLUSIONS: Power spectrum analysis of circadian oscillations of heart rate variability reveals information about the character of LVD. Regular oscillations of time domain indices of HRV were observed in the patients with LVD and in the control group; their amplitude is highest in the control group and lowest in systolic LVD.
