Diabetes Care, Vol 20, Issue 9 1416-1421, Copyright © 1997 by American Diabetes Association
Power spectral analysis of heart rate variability in children and adolescents with IDDM
AM Wawryk, DJ Bates and JJ Couper
Endocrine and Diabetes Unit, Women's and Children's Hospital, North Adelaide, Australia. jcouper@medicine.adelaide.edu.au
OBJECTIVE: To investigate power spectral analysis (PSA) of heart rate
variability (HRV) in children and adolescents with IDDM, its relationship
with other measures of HRV and standard cardiovascular responses, and
factors associated with reduced HVR. RESEARCH DESIGN AND METHODS: A total
of 130 subjects with IDDM aged 12.8 +/- 3.2 years and 108 healthy control
subjects were studied. Power spectra were analyzed from supine
electrocardiograph (ECG) recordings by processing into consecutive R-R
intervals and analysis using fast Fourier transformation. Standard
cardiovascular responses to deep breathing and standing were performed.
RESULTS: IDDM subjects had a reduction in total power including both
low-frequency (0.05-0.14 Hz; P = 0.0001) and high-frequency (0.14-0.40 Hz;
P = 0.0002) components. These changes were seen from diagnosis. Other
measures of HRV, coefficient of variation (CV) and standard deviation (SD)
of mean resting heart rate, were also significantly lower in IDDM. All 20
(15%) of the 130 IDDM subjects with total power less than the 5th
percentile in control subjects also had reduced HRV when measured by CV of
heart rate. There was an independent relationship between age and the
high-frequency component in IDDM subjects and control subjects. Total power
correlated with mean heart rate (r = -0.56; P < 0.0001), CV of heart
rate (r = 0.90; P < 0.00001), SD of heart rate (r = 0.91; P <
0.00001), heart rate response to deep breathing (r = 0.45; P < 0.0001),
and duration in IDDM subjects. There was no correlation with short-term or
long-term metabolic control. Retesting of 27 subjects showed a variability
in total power and its components comparable to other measures of HRV and
standard heart rate responses. CONCLUSIONS: Changes in HRV are a sensitive
and reproducible measure of early autonomic dysfunction in childhood. In
this age-group, PSA appears no more sensitive a measure of reduced HRV than
other closely correlated measures of HRV.