Assessment of Autonomic Disturbance by 24-hour Heart Rate Variability in Patients with Liver Cirrhosis / 대한내과학회지

OBJECTIVE: Heart rate variability(HRV) is helpful to diagnosis autonomic disturbance and sympathetic-parasympathetic imbalance in patients with myocardial infarction and diabetes mellitus. Patients with liver cirrhosis demonstrate reduced blood pressure despite increased heart rate and increased cardiac output, indicating a fall in peripheral vascular resistance. Autonomic disturbance may contribute to this phenomenon. The aim of the present study is to evaluate the degree of autonomic disturbance and the circadian rhythm of autonomic nervous system by estimating HRV with 24 hour-Holter recorder, METHODS: 24 hour-HRV with Del Mar Avionics 563 Holter recorder and cardiovascular reflex tests were carried out on 32 patients with liver cirrhosis and 20 control subjects. We evaluated the presence of autonomic disturbance, and assessed quantitatively the autonomic disturbance. RESULTS: 1) Among cardiovascular reflex tests, Valsalva test, standing test and deep breathing test were showed a significantly decreased response in liver cirrhosis compared with control groups. 2) The standard deviation of 24hours average R-R intervals were showed a significantly decrease in liver cirrhosis than control groups(P<0.0001). The HRV of low frequency(LF. P<.D.001), high frequency(HF, P<0.0001) and total power spectral density (P<0.0001) in liver cirrhosis were statistically lower than control. 3) The LF/HF ratio of patients with liver cirrhosis was showed higher than control at night CONCLUSION: Non-invasive assessment of 24 hour-HRV has a few advantages in the diagnosis and degree of autonomic disturbance, evaluation of diurnal variation of autonomic tone.

Circadian Variation of Cardiac Autonomic Function in Hypertensives

BACKGROUND: We addressed the problem of the circadian changes in neural control of the circulation in ambulant hypertensive subjects. With spectral analysis of heart rate variability the tonic sympathetic and vagal activities and their changes are respectively assessed by the power of 0.050 - 0.015Hz(low frequency, LF) and 0.150 - 0.350Hz(respiratory linked, high frequency, HF) components of the spectrum of the beat by beat variability of RR interval. METHODS: Heart rate variability(HRV) and its circadian rhythm were evaluated in 15 patients with hypertension. By using 24-h Holter monitoring, HRV and its spectral components were measured. Finding were compared with 15 age-matched normal controls. RESULTS: The 24-hour plot of the SDs revealed that heart rate variability was significantly lower in the hypertensive patients, and the differences reached statistical significance during hours 2, 3, 9, 13, 16, 18, 19, and 23(p<0.05). Spectral analysis showed that power in the high-frequency range(0.150 to 0.350Hz) was lower among the hypertensive patients than among the normal controls during 22 of 24 hours but that the difference was statistically significant only during 2 hours(p<0.05). Power in the low frequency range(0.050 to 0.150Hz) was low at night, increased in the morning, and high during the day among controls ; this circadian rhythm was absent among hypertensive patients. CONCLUSIONS: Among hypertensive patients, HRV is decreased with a partial withdrawal of parasympathetic tone, and the circadian rhythm of sympathetic/parasympathetic tone is altered.