Intracardiac pressures in the human fetus

Johnson, Philip M.; Maxwell, D.; Tynan, Michael; Allan, Lindsey D.

doi:10.1136/heart.84.1.59

Cited by 125 publications

(96 citation statements)

References 25 publications

(10 reference statements)

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“…Thus, fetal semilunar valves and the aorta and pulmonary trunk are subjected to equal pressures, which progressively increase during gestation. 21 The present study revealed that fetal, second-trimester semilunar (aortic and pulmonary) valves lacked distinguishable layers, were composed primarily of proteoglycans, had no detectable elastin, had small amounts of disorganized collagen, and were histologically identical (likely because of a similar physiological environment during development 22 ). Valvular ECM elements accommodate repetitive shape and dimension changes throughout the cardiac cycle and must adapt to different mechanical stresses throughout life.…”

Section: Semilunar Valve Architecture Changes Throughout Development mentioning

confidence: 91%

“…21 These hemodynamic changes were associated with decreased VIC activation in late neonatal (1 to 30 days of survival) pulmonary valves (6.3Ϯ0.8%; nϭ5), whereas aortic valve VICs remained activated (20.5Ϯ2.2%, nϭ5; PϽ0.05; Figure 4). Nevertheless, this change did not occur immediately, because the numbers of activated VICs in early neonatal valves with minutes to hours of survival were identical in both pulmonary (20.5%; nϭ5) and aortic valves (20.5%; nϭ5).…”

Section: Fetal Valves Contain Activated Cells That Overexpress Proteomentioning

confidence: 99%

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Human Semilunar Cardiac Valve Remodeling by Activated Cells From Fetus to Adult

et al. 2006

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Background-The evolution of cell phenotypes and matrix architecture in cardiac valves during fetal maturation and postnatal adaptation through senescence remains unexplored. Methods and Results-We hypothesized that valvular interstitial (VIC) and endothelial cell (VEC) phenotypes, critical for maintaining valve function, change throughout life in response to environmental stimuli. We performed quantitative histological assessment of 91 human semilunar valves obtained from fetuses at 14 to 19 and 20 to 39 weeks' gestation; neonates minutes to 30 days old; children aged 2 to 16 years; and adults. A trilaminar architecture appeared by 36 weeks of gestation but remained rudimentary compared with that of adult valves. VECs expressed an activated phenotype throughout fetal development. VIC density, proliferation, and apoptosis were significantly higher in fetal than adult valves. Pulmonary and aortic fetal VICs showed an activated myofibroblast-like phenotype (␣-actin expression), abundant embryonic myosin, and matrix metalloproteinase-collagenases, which indicates an immature/activated phenotype engaged in matrix remodeling versus a quiescent fibroblast-like phenotype in adults. At birth, the abrupt change from fetal to neonatal circulation was associated with a greater number of ␣-actin-positive VICs in neonatal aortic versus pulmonary valves. Collagen content increased from early to late fetal stages but was subsequently unchanged, whereas elastin significantly increased postnatally. Collagen fiber color analysis revealed a progressive temporal decrease in thin fibers and a corresponding increase in thick fibers. Additionally, collagen fibers were more aligned in adult than fetal valves. Conclusions-Fetal

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Section: Semilunar Valve Architecture Changes Throughout Development mentioning

confidence: 91%

Section: Fetal Valves Contain Activated Cells That Overexpress Proteomentioning

confidence: 99%

Human Semilunar Cardiac Valve Remodeling by Activated Cells From Fetus to Adult

et al. 2006

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“…• Two ventricular pumps perfuse the same systemic circulation in a parallel fashion with the right ventricular output being greater than the left 22 .…”

Section: Changes In the Fetal Heart In Iugrmentioning

confidence: 99%

Colour Doppler in IUGR- Where are we and where do we go?

Lulla

Garg

2010

J Obstet Gynecol India

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Intra-uterine growth restriction (IUGR) is an important perinatal problem giving rise to increased morbidity and mortality in the growth restricted fetus. The aim of fetal medicine today, is to prevent the mere occurrence of IUGR in high risk pregnancies and to deliver the fetuses already afflicted with growth restriction, before they have suffered from the effects of hypoxia. The use of Doppler provides this information, which is not readily obtained from the other conventional tests of fetal well being. The Doppler patterns follow a longitudinal trend in the arterial and venous circulation of the fetus as well as the placental vasculature guiding management decisions regarding the appropriate time of delivery. Progressive knowledge of the fetal circulation and its adaptation when the fetus is subjected to hypoxia, has helped us recognize the early signs of IUGR thereby improving the prognosis of these complicated pregnancies. It has therefore become the gold standard in the management of the growth-restricted fetus.

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“…However, the timing of these changes during development and the mechanisms regulating them are incompletely understood (10,26,30,44,48). Furthermore, it is evident that this differs between and within various vascular beds (4,43,53,55).…”

mentioning

confidence: 99%

Vascular development in early ovine gestation: carotid smooth muscle function, phenotype, and biochemical markers

Hutanu¹,

Cox²,

DeSpain³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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Vascular smooth muscle (VSM) maturation is developmentally regulated and differs between vascular beds. The maturation and contribution of VSM function to tissue blood flow and blood pressure regulation during early gestation are unknown. The carotid artery (CA) contributes to fetal cerebral blood flow regulation and well being. We studied CA VSM contractility, protein contents, and phenotype beginning in the midthird of ovine development. CAs were collected from early (88 -101 day of gestation) and late (138 -150 day; term ϭ day 150) fetal (n ϭ 14), newborn (6 -8 day old; n ϭ 7), and adult (n ϭ 5) sheep to measure forces in endothelium-denuded rings with KCl, phenylephrine, and ANG II; changes in cellular proteins, including total and soluble protein, actin and myosin, myosin heavy chain isoforms (MHC), filamin, and proliferating cell nuclear antigen; and vascular remodeling. KCl and phenylephrine elicited age-and dose-dependent contraction responses (P Ͻ 0.001) at all ages except early fetal, which were unresponsive. In contrast, ANG II elicited dose responses only in adults, with contractility increasing greater than fivefold vs. that shown in fetal or neonatal animals (P Ͻ 0.001). Increased contractility paralleled age-dependent increases (P Ͻ 0.01) in soluble protein, actin and myosin, filamin, adult smooth muscle MHC-2 (SM2) and medial wall thickness and reciprocal decreases (P Ͻ 0.001) in nonmuscle MHC-B, proliferating cell nuclear antigen and medial cellular density. VSM nonreceptor-and receptor-mediated contractions are absent or markedly attenuated in midgestation and increase age dependently, paralleling the transition from synthetic to contractile VSM phenotype and, in the case of ANG II, paralleling the switch to the AT1 receptor. The mechanisms regulating VSM maturation and thus blood pressure and tissue perfusion in early development remain to be determined. myosin heavy chain isoforms; nonmuscle myosin; fetal development; receptor and nonreceptor function; smooth muscle growth; angiotensin II SMOOTH MUSCLE DEVELOPMENT normally proceeds in a wellorchestrated manner before and after birth (5,6,11,14,41,53). These changes occur in three phases: cellular differentiation, functional maturation, and growth (42). During differentiation, progenitor cells derived from the mesenchyme are transformed into immature smooth muscle cells (SMC) localized to either visceral or vascular sites. The subsequent maturational changes result in developmentally regulated improvements in specific organ or vascular function essential for the well being and growth of the developing fetus and newborn. For example, functional maturation of the ovine bladder and umbilical artery smooth muscle occurs early in development (4, 6). The former is required for maintenance of fetal fluid balance and establishment of amniotic fluid volume, which permit normal lung development. The latter is essential in the regulation of fetal oxygen and nutrient uptake from the maternal placental circulation and probably blood pressure (4, 32). In co...

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Intracardiac pressures in the human fetus

Cited by 125 publications

References 25 publications

Human Semilunar Cardiac Valve Remodeling by Activated Cells From Fetus to Adult

Human Semilunar Cardiac Valve Remodeling by Activated Cells From Fetus to Adult

Colour Doppler in IUGR- Where are we and where do we go?

Vascular development in early ovine gestation: carotid smooth muscle function, phenotype, and biochemical markers

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