American College of Obstetricians and Gynecologists, Society for Maternal-Fetal .Medicine, American Society of Echocardiography, and American College of Radiology. Echocardiography indications include suspected fetal cardiac anomaly, extracardiac anomaly, or chromosomal abnormality; fetal arrhythmia; hydrops; thick nuchal translucency; monochorionic twin gestation; irst-degree relative to the fetus with a congenital cardiac defect; in vitro fertilization; maternal antiRo or anti-La antibodies; exposure to a medication associated with cardiac defects; and maternal metabolic disease associated with cardiac defects-such as pregestational diabetes or phenylketonuria (American Institute of Ultrasound in Medicine, 2013a). Components of the examination are listed in
TABLE 10-9. Components of Fetal Echocardiography
EvaIuation of atria Evaluation of ventricles Evaluation of great vessels Cardiac and visceral situs Atrioventricular junctions Ventriculoarterial junctions
Scanning planes, gray scale
Right ventricular outflow tract Three-vessel and trachea view Short-axis view, low (ventricles) Short-axis view, high (outflow tracts) Aortic arch aPulsed-wave Doppler sonography should be used as an adjunct to evaluate these structures.
Cardiac biometry and functional assessment are optional but should be considered for suspected structural/ functional abnormalities.
Adapted from the American Institute of Ultrasound in Medicine,l201l3b.
FIGURE 10-30 Endocardial cushion defect. A. During ventricular systole, the lateral leaflets of the mitral and triscuspid valves come together in the midline. But the atrioventricular valve plane is abnormal, a common atrium (A) is observed, and there is a visible defect (arrow) in the interventricular septum. B. During diastolic filling, opening of the atrioventricular valves more clearly demonstrates the absence of their medial leaflets.
Table 10-9, and examples of nine required gray-scale imaging views are shown in Figure 10-28. Examples of selected cardiac anomalies are reviewed below.
Ventricular Septal Defect. This is the most common congenital cardiac anomaly and is found in approximately 1 in 300 births (Cragan, 2009; Dolk, 2010). Even with adequate visualization, the prenatal detection rate of ventricular septal defect (VSD) is low. A defect may be appreciated in the membranous or muscular portion of the interventricular septum in the four-chamber view, and color Doppler demonstrates flow through the defect. Imaging of the left ventricular outflow tract may show discontinuity of the interventricular septum as it becomes the wall of the aorta (see Fig. 10-29). Fetal VSD is associated with other abnormalities and aneuploidy, and chromosomal microarray analysis should be ofered. hat said, the prognosis for an isolated defect is good. More than a third of prenatally diagnosed VSDs close in utero, and another third close in the irst year of life (Axt-Fliedner, 2006; Paladini, 2002).