K. Ajiki et al., AUTONOMIC NERVOUS-SYSTEM ACTIVITY IN IDIOPATHIC DILATED CARDIOMYOPATHY AND IN HYPERTROPHIC CARDIOMYOPATHY, The American journal of cardiology, 71(15), 1993, pp. 1316-1320
To assess autonomic nervous activity in patients with cardiomyopathies
, analysis of heart rate variability was performed using 24-hour ambul
atory electrocardiograms in 14 patients with idiopathic dilated cardio
myopathy (IDC), 15 with hypertrophic cardiomyopathy (HC) and 18 health
y subjects. Heart rate variability during the night and daytime was ca
lculated using fast-Fourier transform, and power spectra were quantifi
ed in 2 frequency bandwidths: 0.00 to 0.15 Hz (low-frequency power [LF
]) and 0.15 to 0.50 Hz (high-frequency power [HF]. Log(HF) was used as
an index of parasympathetic nervous activity. Log (HF) was significan
tly lower and log(LF/HF) was significantly higher IDC. These changes w
ere related to ejection fraction. In HC, lower log(HF) and higher log(
LF/HF) were recognized only during the night, and these changes were i
ndependent of the degree of myocardial hypertrophy. Our results indica
ted attenuation of parasympathetic activity and enhanced sympathetic a
ctivity in HC during the night, and also in IDC. Assessment of autonom
ic imbalance by analysis of heart rate variability may be useful for u
nderstanding the pathophysiology of cardiomyopathies.