In:
Clinical Pediatrics, SAGE Publications, Vol. 19, No. 9 ( 1980-09), p. 585-590
Abstract:
The clinical syndrome known as persistent fetal circulation, or persistent pulmonary hypertension of the newborn, is characterized by maintenance of a high pulmonary vascular resistance after birth. The small pulmonary arteries of the fetus have a thick muscular medial layer; they are very reactive, being actively constricted by the low P O2 levels normally present during fetal life. The pulmonary vascular smooth muscle layer is hypertrophied in conditions that result in chronic fetal hypoxia, or a maintained increase in pulmonary arterial pressure. Normally, pulmonary vasodilation occurs rapidly after birth, partly related to physical expansion with gas, but mainly due to the increased P O2 associated with ventilation with air. Based on these developmental considerations, the factors responsible for an increased pulmonary vascular resistance after birth may be classified in three main groups: (A) Acute vaso constriction due to postnatal hypoxia and aggravated by acidemia; (B) Prenatal increase in pulmonary vascular smooth muscle development; and (C) Decreased cross sectional area of the pulmonary vascular bed due to inadequate numbers of vessels. The various mechanisms that may promote these responses are presented.
Type of Medium:
Online Resource
ISSN:
0009-9228
,
1938-2707
DOI:
10.1177/000992288001900902
Language:
English
Publisher:
SAGE Publications
Publication Date:
1980
detail.hit.zdb_id:
2066146-0
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