Power spectral analysis for autonomic influences in heart rate and
blood pressure variability in fetal lambs.
Kimura, Yoshitaka, Kunihiro Okamura,takanori Watanabe,jun Murotsuki,
Taku Suzuki, Masahiro Yano, and Akira Yajima.
Department of Obstetrics and Gynecology, Tohoku University School
of Medicine, 1-1 Seiryomachi, Aobaku, Sendai 980-77, Japan
APStracts 3:0079H, 1996.
Variability of R-R intervals and arterial blood pressure signals in
chronically instrumented fetal lambs were analyzed by power spectral
analysis based on an assumption of maximum entropy. There were four
consistent components; very low (VL, 0.01-0.025 c/b), low (L, 0.025
-0.125 c/b), middle (M, 0.125-0.2 c/b) and high (H, 0.2-0.5 c/b), in
the normal heart rate variability spectrum and the blood pressure
spectrum. Integrated peaks in the power spectrum were compared before
and after the administration of sympathetic and parasympathetic
blockades. [circumflex]a sympathetic blockade reduced the spectral
power in the VL and the L frequency component. [circumflex]a
-sympathetic blockade reduced only the M frequency component in the
spectrum of R-R interval variability. Parasympathetic blockade
reduced the H and L frequency component in the spectrum on R-R
intervals variability spectrum, but increased these components in the
systolic blood pressure variability spectrum. The results clearly
demonstrate the association between fetal autonomic activity and the
change of the power spectrum of heart rate and blood pressure
variability.
Received 10 October 1995; accepted in final form 13 February
1996.
APS Manuscript Number H946-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96