Fetal echocardiography has a high correlation with postnatal and neonatal echocardiographic findings. Delivery management plans may be based on fetal echocardiogram diagnoses.
Fetal echocardiography facilitates the prenatal diagnosis of infants with congenital heart disease (CHD) and through sequential examinations, allows assessment of fetal hemodynamics and cardiovascular status from the time of diagnosis to delivery. Fetal cardiologists have created diagnostic protocols aimed at risk stratifying severity and potential postnatal compromise in fetuses with CHD, and identifying those who may require special intervention at birth or within the first days of life. In this article, we review fetal cardiovascular physiology, the progression of CHD in utero and fetal echocardiographic findings used for risk stratification of newborns with CHD, as well as some of the basic principles of planning for the neonatal resuscitation and initial transitional care of these complex newborns.
The aryl hydrocarbon receptor (AhR) was originally characterized because of its high affinity binding of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin. However, studies using AhR-null mice have demonstrated the importance of this protein in normal physiology and development. Here we demonstrate that AhR-null embryos develop cardiac enlargement, and that this phenotype is dependent, at least in part, on the maternal genotype. Neonates born to AhR-null females had increased heart weights regardless of the neonatal genotype, an outcome also observed in gestational diabetes. The cardiac hypertrophy markers, beta-myosin heavy chain and atrial natriuretic factor, and the cardiac proliferative index were increased in AhR-null embryos, indicating that the cardiac enlargement is associated with myocyte hypertrophy and hyperplasia, which begin prior to birth. Importantly, two- to three-month-old pregnant and seven-month-old nonpregnant females, but not nonpregnant three-month-old AhR-null females had significantly decreased fasting plasma insulin levels and a reduced ability to respond to exogenous insulin compared to controls. Despite these alterations in insulin regulation and responsiveness, pregnant AhR females did not have abnormal glucose tolerance tests and did not develop hyperglycemia, classic characteristics of gestational diabetes. However, twenty-three percent of seven-month-old AhR-null females did have altered glucose tolerance tests, but did not show hyperglycemia or increased hemoglobin A1C concentration under normal feeding conditions. While the ultimate cause of the neonatal phenotype remains unclear, these studies establish that the AhR is required for normal insulin regulation in pregnant and older mice and for cardiac development in embryonic mice.
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