A. Frattola et al., TIME AND FREQUENCY-DOMAIN ESTIMATES OF SPONTANEOUS BAROREFLEX SENSITIVITY PROVIDE EARLY DETECTION OF AUTONOMIC DYSFUNCTION IN DIABETES-MELLITUS, Diabetologia, 40(12), 1997, pp. 1470-1475
Diabetic autonomic dysfunction is associated with a high risk of morta
lity which makes its early identification clinically important. The ai
m of our study was to compare the detection of autonomic dysfunction p
rovided by classical laboratory autonomic function tests with that obt
ained through computer assessment of the spontaneous sensitivity of th
e baroreceptor-heart rate reflex (BRS) by lime domain and frequency do
main techniques. In 20 normotensive diabetic patients (mean age +/-SD
41.9 +/- 8.1 years) with no evidence of autonomic dysfunction on labor
atory autonomic testing (DO) blood pressure (BP) and ECG were continuo
usly monitored over 15 min in the supine position, SRS was assessed as
the slope of the regression line between spontaneous increases or red
uctions in systolic BP and linearly related lengthening or shortening
in RR interval over sequences of al feast 4 consecutive beats (sequenc
e method), or as the squared ratio between RR interval and systolic BP
spectral powers around 0.1 Hz. We compared the results with those of
32 age-matched normotensive diabetic patients with abnormal autonomic
function tests (D1) and with those of 24 healthy age-matched control s
ubjects with normal autonomic function tests (C). Compared to C, BRS w
as markedly less in D1 when assessed by both the slope of the two type
s of sequences (data pooled) and by the spectral method (-71.3 % and -
60.2 % respectively, both p < 0.01). However, BRS was consistently alt
hough somewhat less markedly reduced in DO, the reduction being clearl
y evident for all the estimates (-57.0 % and -43.5 %, both p < 0.01).
The effects were more evident than those obtained by the simple quanti
fication of the RR interval variability. These dal-a suggest that time
and frequency domain estimates of spontaneous BRS allow earlier detec
tion of diabetic autonomic dysfunction than classical laboratory auton
omic tests. The estimates can be obtained by short non-invasive record
ing of the BP and RR interval signals in the supine patient, i.e. unde
r conditions suitable for routine outpatient evaluation.