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1.
Andrew
M Wawryk, MBBS, FRACP,
2.
David
J Bates, PHD and
3.
Jennifer
J Couper, MD, FRACP
+ Author
Affiliations
1.
Address
correspondence and reprint requests to Jennifer Couper,
MD, Endocrine and Diabetes Unit, Women's and Children's Hospital, 72 King
William Rd., North Adelaide, SA 5006 Australia. E-mail: jcouper@medicine.adelaide.edu.au
http://care.diabetesjournals.org/content/20/9/1416.short
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 ¡Ó 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¡V0.14 Hz; P = 0.0001) and high-frequency
(0.14¡V0.40 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 < 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.