Cyanosis screening
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
Screening
Guidelines for the performance of fetal echocardiograms recommend:
- Color Doppler are used to identify small vessels such as the pulmonary veins, ductus venosus, and ductus arteriosus, to assess valvular competence and flow patterns, and to examine the ventricular septum for defects.
- Three-dimensional and four-dimensional echocardiography, tissue Doppler, strain and strain rate imaging, fetal electrocardiography, fetal magnetocardiography, and cardiovascular magnetic resonance imaging [14].
- When a fetal cardiac abnormality is detected, additional evaluation and follow-up are indicated.
- Patients who have a normal basic fetal cardiac evaluation and echocardiography generally do not require further evaluation unless there is an elevated risk of evolution of fetal heart disease later in pregnancy.
- The identification of a fetal cardiac defect should prompt a thorough search for extracardiac abnormalities, since these are detected in at least 20 to 40 percent of cases, depending on the population (eg, midtrimester fetuses versus liveborns versus liveborns and stillborns) [33-35].
- Cardiac anomalies are part of numerous fetal syndromes [36,37]. An analysis of data compiled from 20 registries of congenital malformations reported that approximately 4 percent of the patients with cardiac anomalies had an identifiable syndrome [37].
- Congenital heart disease is associated with an increased risk for adverse neurodevelopmental outcome, which has been attributed to factors such as associated chromosomal abnormalities, syndromes, postnatal cardiac dysfunction, perioperative factors in infants who require surgical treatment, and possibly in utero hemodynamic abnormalities. In children with isolated cardiac abnormalities, the frequency of neurodevelopment development also depends on the specific abnormality.
- Prenatal neuroimaging findings are generally not predictive of postnatal neurodevelopmental outcome. A systematic review and meta-analysis of studies of prenatal ultrasound and magnetic resonance imaging (MRI) found that brain abnormalities, delay in head growth, and brain-sparing were observed in subgroups of fetuses with congenital heart disease [38]. However, the prognostic significance of these findings was unclear because large MRI studies were scarce, ultrasound data were biased towards severe and left-sided heart abnormalities, and long-term follow-up studies correlating prenatal and postnatal findings were limited.
Genetic assessment
- Fetal genetic assessment is indicated because chromosome abnormalities are common in fetuses with cardiac defects, even when isolated.
- The risk of fetal aneuploidy varies depending on the malformation. [14]:
- Atrioventricular septal defect
- Truncus arteriosus
- Double-outlet right ventricle/conotruncal malformations
- Coarctation/arch interruption
- Tricuspid valve dysplasia
- Tetralogy of Fallot
- Hypoplastic left heart syndrome
- Pulmonic stenosis/atresia with intact ventricular septum
- Heterotaxy/cardiosplenic syndromes
- Transposition of great arteries
- the 22q11 deletion has been associated with several cardiac anomalies, including interrupted aortic arch, truncus arteriosus, ventricular septal defect, and tetralogy of Fallot [14].
- The two main approaches for genetic testing are:
- G-banding of fetal cells obtained via amniocentesis, with fluorescent in situ hybridization (FISH) to assess for microdeletions, such as 22q11, not detectable by visual banding techniques, and
- chromosomal microarray, which detects submicroscopic chromosomal abnormalities in 5 percent of fetuses with ultrasound-detected anomalies and a normal G-band karyotype. Disadvantages of chromosomal microarray are that balanced rearrangements are not detectable and variants of unknown significance may be identified.