RESUMEN
Background: Heart failure is a common clinical condition and is the late stage of most cardiovascular diseases. Heart rate disorder is one of the causes of deaths in patients with chronic heart failure. There is few number of studies on Heart Rate Variability (HRV) in Vietnam. Objective: To study the change of HRV time in patients with chronic heart failure. Subject and Method: A prospective, descriptive and cross-sectional study was carried out on 105 subjects including 73 patients with chronic heart failure and 42 normal persons as controls. Time domain measurements of HRV were calculated from 24 hour electrocardiographic Holter (Holter WIN P-V, USA) on all 105 subjects. In the chronic heart failure group, there were 51 men and 22 women with the mean age of 62.8+/-11.2, control group including 30 men and 12 women with the mean age of 61.5+/-5.7. Results and conclusion: (1) There was a decrease of time domain of HRV showed the decrease of parasympathetic tone in patients with chronic heart diseases. (2) The higher degree of heart failure, the lower the time domain of HRV.