Autonomic Cardiovascular Regulation in the Newborn

Autonomic Cardiovascular Regulation in the Newborn

Peter Andriessen (Máxima Medical Center, The Netherlands)
Copyright: © 2012 |Pages: 21
DOI: 10.4018/978-1-4666-0975-4.ch009
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Abstract

This paper reviews the baroreflex mediated heart rate response in human infants with a focus on data acquisition, signal processing and autonomic cardiovascular modeling. Baroreflex mediated heart rate response is frequently used as an estimate of autonomic cardiovascular regulation. Baroreflex mediated heart rate response may be viewed in terms of a negative-feedback system. To study fluctuations in this feedback system, continuous registration of ECG and blood pressure waveforms are required. From these waveforms, time series of R-R interval and blood pressure values are derived. This paper focus on spontaneous baroreflex sensitivity (e.g., R-R interval change per unit of arterial blood pressure change, ms/mmHg) calculated from cross-spectral analysis of spontaneous occurring changes in R-R interval and blood pressure. Despite different methodology (sequence method; transfer function analysis; head-up tilt) there is fairly good agreement of spontaneous baroreflex sensitivity values during homeostasis. Preterm infants and term newborns have values of 2-4 and 10-15 ms/mmHg, respectively. These values are much lower than found in adults, approximately 25 ms/mmHg. The clinical relevance of a limited baroreflex function may be that acute perturbations of the cardiovascular system are poorly counteracted and may result in poor cerebral perfusion.
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Background

The importance of cardiovascular reflex control is to supply appropriately oxygenated blood to the different tissues in the face of disturbances of circulatory homeostasis (Timmers, Wieling, Karemaker, & Lenders, 2003). The sensory monitoring for the circulatory homeostasis entails (1) mechanical information about pressure in the arterial system and (2) chemical information about the level of oxygen and carbon dioxide in the blood. After integration in the brainstem efferent information is conveyed through the parasympathetic system and sympathetic system to the different effectors. Figure 1 shows a diagram of these neuronal pathways that are involved in autonomic cardiovascular regulation.

Figure 1.

Anatomic substrate of the autonomic cardiovascular regulation (Purves, Augustine, Fitzpatrick, Katz, LaMantia, McNamara, & Sunderland, 2001. Permission to reproduce image by Sinauer)

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