Figures
Fig. 1: Four-chamber views of different fetal conditions. Panel a shows normal fetal anatomy, whereas panels b to f depict cardiac anomalies, which will be discussed and further delineated within the paper.
Fig. 2: Ebstein’s anomaly at 32 completed weeks with STIC volume reconstruction and automatic labeling using FINE method. All nine diagnostic planes are clearly depicted. The 3-vessel-trachea view shows a size discrepancy of the great vessels with a small transverse aorta. The 4-chamber view is abnormal with a marked left rotation (63 degrees) and ventricular asymmetry (LV<RV) and demonstrates apically displaced tricuspid valve hinges (atrialization of the RV; aRV) with somewhat thickened septal and lateral leaflets. In both the 5-chamber view (5CV) and left ventricular outflow tract (LVOT) views, there is a small ascending aorta corresponding to tubular aortic stenosis. The RVOT view shows normal main and right branch pulmonary arteries and aRV. There is no regularly filled stomach in the abdominal plane. The ductal arch view depicts the rotated tricuspid valve and gives an impression of the remaining genuine RV. In contrast, the aortic arch is rather hypoplastic, which confirms the finding of an obstructed LVOT. In addition, an enlarged RA can be seen. The vena cave view denotes similar findings.
A - transverse aortic arch; Ao - aorta; Desc - descending; IVC - inferior vena cava; LA - left atrium; LV - left ventricle; P - pulmonary artery; PA - pulmonary artery; RA - right atrium; RV - right ventricle; RVOT - right ventricular outflow tract; S - superior vena cava; SVC - superior vena cava; Trans - transverse.
Fig. 3: Tricuspid atresia at 22 gestational weeks. FINE application on STIC volumes in both cases showed hypoplastic right-sided cardiac structures. While assessing the altered anatomy in detail, subtle but functional important differences can be noted. Whereas the 3VT view in the left panel (a) demonstrates an only slightly smaller main pulmonary artery, there is a hardly a visible pulmonary arm in panel b, corresponding to a severely hypoplastic or atretic RV outflow. The RV in panel b is small and hypocontractile due to an obstructed inflow via the atretic TV. The findings are referred to as hypoplastic right heart (in contrast to the typical findings of tricuspid atresia shown in panel a). A perimembranous VSD was seen in the 4CV, 5CV and LVOT views (panel a); this interventricular communication could only be assumed in the 4CV view (panel b). There was a normal interatrial communication via a patent foramen ovale. The ductal arch view in panels a and b is abnormally thin. The LVOT as well as the aortic arch in both cases are normal.
Fig. 4: Severe pulmonary stenosis seen at 29 weeks. Diagnostic plane reconstruction using FINE shows moderate cardiomegaly and a slight left-rotated cardiac axis. The main pulmonary artery depicted in the 3VT view is narrow due to a thickened pulmonary valve (PV). There is a moderate asymmetry in ventricular and atrial size, and the tricuspid valve leaflets appear to be thickened (related to marked regurgitation confirmed by additional Doppler interrogation). The RV cavity is narrow but shows myocardial hypertrophy. The LVOT is otherwise normal; on the other hand, the RVOT shows an hourglass-like appearance with an echoic, thickened PV corresponding to valvular stenosis. Both arch views as well as the bicaval plane are normal.
Fig. 5: Fetus with critical pulmonary stenosis and an intact ventricular septum at 33 weeks (panel a) and complex cardiac anomaly with pulmonary atresia and an intact ventricular septum, tricuspid atresia, LVOTO and pericardial effusion at 17 weeks (panel b). In both cases, there is a marked cardiomegaly in late and early pregnancy caused by a significant RVOT obstruction. The characterizing anatomic sequelae of RVOTO are clearly depicted after reconstruction using FINE. The 3VT view in both cases is abnormal. In panel a, both vessels are equal in size, and the PV is thickened and domed through cardiac cycle. In panel b, the pulmonary artery cannot be visualized, resulting in an ‘I’-shaped appearance on the 3VT view. The entire cardiac morphology is distorted, and the cardiac axis is left-rotated. In panel a, the massively enlarged heart occupies more than half of the thorax (merely due to the dilated RA) and extends from wall to wall. The RV is round, and the myocardium shows marked hypertrophy. The TV leaflets appear dysplastic and thickened (Doppler ultrasound revealed regurgitation of >2 m/s). In panel b, the TV is atretic, the LV is normal, and the MV is patent. The RVOT plane confirms the narrow pulmonary trunk that bifurcates into the pulmonary arteries (panel a), and no detectable pulmonary artery is visible in panel b. The ductal arch in both cases is narrow or hypoplastic. The bicaval plane shows the enlargement of the RA and normal venoatrial arrangement.
Fig. 6: Antenatal cases with different types of DORV (a-d). 3D-reconstructed planes showing the complexity of malposition of both great arteries. In all cases, the 3VT view shows an abnormal parallel course of both outlet vessels arising from the anatomical RV. The spatial arrangement of the aorta is right anterior in panel a (TGA type at 20 gestational weeks), and it is considerably smaller than the main pulmonary artery. This size discrepancy is confirmed in the LVOT and aortic arch cut section views. There is a huge VSD displayed in the 5CV and LVOT views (noncommitted). The 4CV view further shows a common atrium and atretic mitral valve but normal cardiac axis. The latter also applies to the cardiac specimens in panel b and c (compared to a marked left rotation in panel d). Panels b-d show both vessels located in a side-by-side position, representing the most common anatomic variant of DORV. According to the accompanying VSD, panels b and d show a doubly committed arrangement of both outlet vessels. Note the extremely small LV with an atretic MV and the diminished size of the main pulmonary artery (3VT, RVOT) in panel d (seen in the 4CV, 5CV, and LVOT views).
Fig. 7: Tetralogy of Fallot at 22 weeks of gestation. The 3VT view shows both vessels nearly equal in size with a patent DA, and the 4CV view appears to be normal (the cardiac axis is slightly left-rotated). There is a perimembraneous VSD with an overriding medially shifted ascending aorta seen in the 5CV and LVOT views. The RVOT and ductal arch views basically show the main pulmonary artery to be smaller than expected.
Fig. 8: Fetus with ToFAPVS at 29 gestational weeks. The complex cardiac anomaly can be depicted in its entirety in 8 of 9 diagnostic planes. Nonrestrictive interventricular communication in the membranous septum. The 3VT view is distorted with no arterial duct. The cardiac proportions are altered, and the cardiac axis is left rotated, as seen in the 4CV, 5CV and LVOT views. There is an overriding aorta with a broad aortic root, and, most strikingly, both the LVOT and RVOT planes show a marked bulging of the main and branch pulmonary arteries and a tiny hourglass-like narrowing at the level of the absent pulmonary valve. The ductal arch cannot be properly reconstructed due the absent DA. The aortic arch and the bicaval plane are otherwise normal.