Coarse graining spectral analysis of heart rate and blood pressure
variability in patients with autonomic failure.
Blaber, A. P., R. L. Bondar, R. Freeman.
Centre for Advanced Technology Education, Ryerson Polytechnic
University, 350 Victoria Street, Toronto, Ontario, CANADA M5B 2K3,
Department of Neurology, Deaconess Hospital, 110 Francis St., and
Harvard Medical School, Boston MA 02215
APStracts 3:0120H, 1996.
We examined heart rate and blood pressure variability (HRV and BPV),
during graded tilt (five minutes in each of : supine, _10 degrees ,
10 degrees , 30 degrees , 60 degrees , _10 degrees , supine), in
autonomic failure patients and age matched controls. Heart rate was
not different between patients and controls and increased with tilt
(p<0.001). Total HRV was reduced in patients (p<0.03).
Patients had reduced low frequency (0 to 0.15 Hz) HRV and BPV
(p<0.005). With tilt, low frequency BPV increased in controls;
whereas, high frequency (>0.15 Hz) BPV increased in patients.
The slope of the fractal component ([beta]) for HRV and BPV was not
different between patients and controls. HRV [beta] increased (1.5 to
1.9, p<0.01) with tilt, but BPV [beta] (1.8) was unaffected.
Values of [beta] close to 1 indicate high signal regulatory
complexity and values of [beta] close to 2 indicate low complexity.
HRV and BPV provide clear evidence of impaired sympathetic and
parasympathetic autonomic nervous system response to tilt with
autonomic failure. The similarity in signal complexity with reduced
fractal and harmonic spectral power, in patients compared to
controls, suggests unchanged cardiovascular neural input and
integration with reduced output in autonomic failure.
Received 26 October 1995; accepted in final form 7 March 1996.
APS Manuscript Number H1007-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96