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Chapter 44 Fetal Echocardiography

Video 44.1 View obtained in a routine fetal echocardiogram and the typical features of a normal fetus without cardiac pathology: technique for determining situs of the viscera and atria

One starts with the fetus imaged in long axis with the head to the right of the screen. Rotating clockwise 90°, using the left hand, with the palm of the hand oriented towards the fetal spine, the left thumb should point in the direction of the left side of the fetal chest.

Video 44.2 View obtained in a routine fetal echocardiogram and the typical features of a normal fetus without cardiac pathology: normal four-chamber view in a 22-week fetus

The heart is largely within the left chest, the size of the heart is roughly one-third the size of the chest, and the axis of the ventricular septum from the midline is roughly 45°. From this view, one can see symmetry of the atria and ventricles, slight offset of the atrioventricular valves with the tricuspid valve attached lower down on the septum and the moderator band in the apex of the right ventricle. The descending aorta sits behind the posterior left atrial wall near the left pulmonary veins (feature of a left aortic arch). The pulmonary veins can be seen joining the left atrium. Finally, both ventricles can be seen contracting similarly.

Video 44.3 View obtained in a routine fetal echocardiogram and the typical features of a normal fetus without cardiac pathology: normal outlet and arch sweep

Sweeping towards the fetal head from the four-chamber view, the first outlet encountered is the aorta, which courses from the left ventricle towards the right to meet the ascending aorta. The arch then crosses the midline to meet the descending aorta. Sweeping further towards the head, the pulmonary outflow is seen. The main pulmonary artery remains to the left of the midline joining the ductus arteriosus and descending aorta. Note that the great arteries cross, they are relatively symmetric in size, and both valves are thin and open completely. The arches are also symmetric and dive to the left of the trachea.

Video 44.4 View obtained in a routine fetal echocardiogram and the typical features of a normal fetus without cardiac pathology: normal three-vessel and trachea view

The normal three-vessel and trachea view is obtained by sweeping further toward the fetal head and displays cross-sectional images through the fetal superior mediastinum. The pulmonary artery is most leftward and anterior, the ascending aorta in its short axis is slightly more posterior and rightward, and the superior vena cava, also in its short axis, is most posterior and rightward. The right pulmonary artery is seen arising from the main pulmonary artery and coursing horizontally to the fetal right. Sweeping further towards the fetal head, both arches can be seen diving towards the left of the trachea to meet the descending aorta close to the spine.

Video 44.5 Findings of an almost 20-week fetus with heterotaxy/polysplenia syndrome and dextrocardia

In this video, the bottom of the image represents the right side of the fetus. The heart, which is enlarged, is predominantly located in the right chest with the apex pointing rightward (bottom of the image) consistent with dextrocardia. A complete balanced atrioventricular canal is present, and the ventricles appear to be L-looped. The descending aorta is present to the left of the spine. Just beneath it, which is rightward in the fetus, is another vessel that represents the dilated azygos in the context of an interrupted inferior vena cava. Finally, complete atrioventricular block is present. The ventricular myocardium appears hypertrophied and dysfunctional, and a small pericardial effusion is present.

Video 44.6 Findings of an almost 20-week fetus with heterotaxy/polysplenia syndrome and dextrocardia

In this sagittal view of the fetus, a normal ductus venosus and hepatic veins are present, but the intrahepatic inferior vena cava is not. The finding of an interrupted inferior vena cava is typical for heterotaxy/polysplenia syndrome, which is more likely to be associated with bradycardia and/or complete heart block.

Video 44.7 Findings of a 25-week fetus with severe aortic stenosis with evolving hypoplastic left heart syndrome

The aortic valve is thickened with restricted opening. The left ventricle also appears dilated and dysfunctional, and the endocardium appears echo-bright, consistent with evolving endocardial fibroelastosis.

Video 44.8 Findings of a 25-week fetus with severe aortic stenosis with evolving hypoplastic left heart syndrome

The addition of color Doppler demonstrates accelerated flow across the aortic valve with a narrowed vena contracta consistent with aortic stenosis. Mild mitral regurgitation is also present.

Video 44.9 Findings of a 25-week fetus with severe aortic stenosis with evolving hypoplastic left heart syndrome

The sagittal view of the arch demonstrates antegrade flow in the ascending aorta but retrograde flow throughout the arch consistent with the evolving inability of the left side to support the systemic circulation, i.e., hypoplastic left heart syndrome by the time of birth.

Video 44.10 Sweep demonstrating the anatomy of a vascular ring by color flow mapping

The left side of the fetus is at the top of the screen. The right aortic arch, aberrant left subclavian artery (coursing behind the trachea), and a left ductus arteriosus can be seen coursing in a ring around the trachea. At the end of the loop, the aberrant left subclavian artery courses towards the transducer (red).

Video 44.11 Fetal rhabdomyomas: multiple, homogenous tumors in a four-chamber view in a 32-week fetus

The echotexture of the tumors is similar to the adjacent myocardium consistent with the diagnosis of rhabdomyomas. Although both ventricles appear to have significant tumor burden, there is no inflow or outflow tract obstruction, and the ventricular function is preserved. Note the shadowing artifact from the ossifying ribs in this late-gestation fetus, which is a typical time for the diagnosis of this lesion.

Video 44.12 Fetal cardiomyopathy: abnormal four-chamber view in the setting of fetal cardiomyopathy in a 22-week fetus with normal cardiac connections and levocardia

There is significant biventricular hypertrophy with a very reduced biventricular systolic function. A right-sided pleural effusion, likely representing hydrops fetalis, is noted.

Video 44.13 Severe Ebstein anomaly of the tricuspid valve in a 33-week fetus

There is severe tricuspid regurgitation and a massively dilated right atrium. Due to displacement of the septal leaflet of the tricuspid valve, the regurgitant jet arises from near the right ventricular apex. Left ventricular systolic function appears to be preserved at this time although there is mild mitral regurgitation (small red jet in diastole).

Video 44.14 Severe Ebstein anomaly where the right ventricle is unable to generate a pressure to eject through the pulmonary valve and the pulmonary valve is regurgitant in both systole and diastole

This represents a circular shunt with the potential to steal from the systemic and placental circulations. If severe, it can lead to fetal hydrops, hypoxemia, and demise.

Video 44.15 Example of supraventricular tachycardia in a 24-week fetus

Atrial and ventricular contractions are 1 : 1, and at a rate of 240-250 bpm this may most likely represent either atrioventricular re-entry supraventricular tachycardia or ectopic atrial tachycardia. Further evaluation through the use of M-mode and Doppler would confirm the mechanism.

Video 44.16 Example of complete atrioventricular block with bradycardia

Four-chamber imaging in a fetus whose mother had high titers of anti-SSA antibodies associated with systemic lupus erythematosus. In addition to the complete atrioventricular block, there is echogenic speckling of the endocardium consistent with endocardial fibroelastosis secondary to myocardial damage due to the antibodies.

Video 44.17 Example of complex cardiac anatomy in a twin fetus at 13 weeks

This fetus has a final diagnosis of double-inlet left ventricle with a smaller left atrioventricular valve, overriding aorta, and a rightward right ventricular outflow tract with pulmonary atresia. Cross-sectional imaging through the fetal abdomen sweeping cephalad shows the left of the fetus to the left of the screen. There is situs solitus with a rightward inferior vena cava and leftward descending aorta. There is a dominant right-sided liver and left-sided stomach with a spleen positioned behind the stomach. In the short four-chamber image, there is levocardia, the pulmonary veins join the left-sided atrium, and a single patent right-sided atrioventricular connection and smaller right-sided outlet chamber with ventricular septal defect is seen.

Video 44.18 Example of complex cardiac anatomy in a twin fetus at 13 weeks

In the same fetus as in Video 44.17, sweeping from the four-chamber view to the outlets, the larger aorta which overrides the ventricular septum is seen and there is a smaller, rightward outlet chamber.

Video 44.19 Example of complex cardiac anatomy in a twin fetus at 13 weeks

In the same fetus as in Video 44.17, in color imaging, there is antegrade flow through the aortic arch (blue) but reversed flow through the ductus arteriosus into the main pulmonary artery (red) in keeping with critical pulmonary outflow obstruction.