Regulation of heart rate variation by the autonomic nervous system in neonatal lambs

Regulation of heart rate variation by the autonomic nervous system in neonatal lambs

We studied the role of the autonomic nervous system in the regulation of heart rate variation (HRV) in 12 chronically instrumented neonatal lambs. HRV was quantified from ECG tracings by computing periodic HRV distributions at frequencies of 0.02-1.00 Hz, using power spectral analysis of heart rate,...

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Bibliographic Details
Published in:Pediatric research Vol. 27; no. 4; pp. 383 - 391
Main Authors: SIIMES, A. S. I, VÄLIMÄKI, I. A. T, ANTILA, K. J, JULKUNEN, M. K. A, METSALA, T. H, HALKOLA, L. T, SAMULI SARAJAS, H. S
Format: Journal Article
Language:English
Published: Hagerstown, MD Lippincott Williams & Wilkins 01-04-1990
Subjects:
Animals
Animals, Newborn - physiology
Autonomic Nervous System - physiology
Biological and medical sciences
Gynecology. Andrology. Obstetrics
Heart Rate - physiology
Management. Prenatal diagnosis
Medical sciences
Pregnancy. Fetus. Placenta
Receptors, Adrenergic, beta - physiology
Sheep
Vagus Nerve - physiology
Doppler ultrasound study
Human
Well being
Umbilical artery
Systole
In utero
Gestational age
Pulmonary artery
Screening
Fetal diseases
Fetal hypotrophy
Follow up study
Aorta
Fetus
Hemodynamics
Supervision
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Summary:We studied the role of the autonomic nervous system in the regulation of heart rate variation (HRV) in 12 chronically instrumented neonatal lambs. HRV was quantified from ECG tracings by computing periodic HRV distributions at frequencies of 0.02-1.00 Hz, using power spectral analysis of heart rate, and also by HRV indices. Heart rate declined more during the 1st than the 2nd mo after birth. Multiple regression analysis showed that the heart rate responses to vagal and to beta-adrenergic blockade had an independent negative association both with age and with the initial mean heart rate, whereas the overall HRV response had a positive association with age. Vagal blockade led to a 70-80% decrease in the beat-to-beat HRV in all lambs (p less than 0.001). The overall HRV indices decreased by 40-65% in lambs (less than 30 d old (p less than 0.001) and about 30% in those greater than 30 d old (p less than 0.05). In the power spectrum the greatest decrease was seen in the high-frequency components of HRV. beta-Blockade led to a decrease of about 50% in all HRV (p less than 0.001) in the younger lambs, without frequency selection. In the older lambs, it had no effect on the beat-to-beat HRV, but the overall HRV (coefficient of variance) decreased maximally by 40% (p less than 0.01), with a significant reduction in the low-frequency components of HRV. These results suggest that in the regulation of HRV after birth dual control via the autonomic nervous system is most important. In the older lambs, developmental changes result in precise regulation of the fast heart rate fluctuations mainly by the vagal division, whereas the slow fluctuations are partially regulated by the vagal and beta-adrenergic divisions.
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ISSN:0031-3998
1530-0447
1530-0447
DOI:10.1203/00006450-199004000-00012