Fetal and Neonatal Cardiology
Benjamin W. Eidem
M. Yasir Qureshi
Jay D. Pruetz
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1. Which of the following is the most common indication to refer for formal fetal echocardiography?
A. Maternal TORCH infection
B. First-degree relative with congenital heart disease
C. Fetal arrhythmia
D. Suspected cardiac anomaly on obstetrical screening ultrasound
E. Maternal phenylketonuria (PKU) with phenylalanine level >10 mg/dL
1. (D) Abnormal findings suggestive of a fetal cardiac anomaly on obstetrical screening ultrasound is the most common reason to refer for formal fetal echocardiography, and in ˜40% to 50% of these pregnancies, CHD is confirmed. However, all of these are appropriate indications for performing a fetal echocardiogram. Of note, rubella is an extremely rare maternal infection, but does carry increased risk for CHD, especially pulmonary stenosis. Fetal rhythm abnormalities affect ˜1% to 2% of pregnancies and account for <10% of referrals for formal fetal echocardiography. PKU is a rare metabolic disorder that in pregnant women is associated with CHD, particularly when the mother’s diet is not well controlled. There is a 10- to 15-fold increased risk of CHD in the fetus when the mother has elevated maternal serum levels of phenylalanine >15 mg/dL. However, if the mother has good preconception control and maintains levels <10 mg/dL during the first trimester, the risk is greatly reduced and a fetal echocardiogram may not be necessary.
2. Doppler flow studies in the human fetus have shown that the ratio of right-to-left ventricular combined output is approximately which of the following?
2. (C) The right ventricle ejects 55% to 60% of combined fetal cardiac output while the left ventricle ejects 40% to 45%. Cardiac output increases significantly during gestation, but the relative amounts of output from these two parallel circulations remain relatively the same.
3. While fetal teratogen exposure is rare, it is still a known risk factor for the development of congenital heart disease. Which of the following fetal teratogen and CHD pairs is correct?
A. Alcohol and Ebstein anomaly
B. Salicylates and ventricular septal defects (VSDs)
C. SSRIs and premature ductus arteriosus closure
D. Lithium and persistent pulmonary hypertension in the newborn
E. Retinoic acid and conotruncal anomalies
3. (E) Retinoic acid is a vitamin A derivative used to treat severe acne and has been associated with increased risk of fetal anomalies in multiple organ systems (CNS, craniofacial, branchial arches, and cardiac). Cardiac anomalies most often seen in retinoic acid exposure included conotruncal defects and aortic arch anomalies. The other answers are paired incorrectly. Alcohol exposure has an increased risk of septal defects such as VSD in association with fetal alcohol syndrome. Salicylates such as NSAIDs (indomethacin) are associated with premature ductus arteriosus closure usually due to exposure with the highest risk in the third trimester. Fortunately, the constriction is usually mild and can be reversed with discontinuation of the drug if recognized early. Lithium is associated with Ebstein anomaly, but more recent studies have suggested lower risk level than previously thought.
4. Fetal echocardiography often employs many different views to confirm normal cardiac anatomy in the fetus and rule out congenital heart defects. Which of the following congenital heart lesions is most likely to be detected on a standard four-chamber view of the fetal heart?
A. Vascular ring
B. Large muscular ventricular septal defect (VSD)
C. d-Transposition of the great arteries (d-TGA) with intact ventricular septum
D. Right aortic arch
4. (B) The standard four-chamber view of the heart is good for visualizing the atria, ventricles, atrioventricular valves, pulmonary veins, and ventricular septum. In addition, it is good for assessing cardiac size and position within the fetal thorax. The three-vessel view and three-vessel tracheal views are used to assess for arch anomalies such as vascular ring and right aortic arch. The outflow tract views are used to assess for conotruncal defects such as tetralogy of Fallot and d-TGA. The sagittal arch views are best for assessing the ductal and aortic arch for conditions such as coarctation, but the three-vessel tracheal view can also be used to assess these structures.
5. A fetal echocardiogram uses various imaging modalities in addition to standard 2D views (grayscale) including the use of spectral Doppler (pulsed-wave) and color Doppler. The use of spectral Doppler (pulsed-wave) is often essential to making which one of the following diagnoses?
A. Vascular ring
B. d-Transposition of the great arteries (d-TGA)
C. Premature atrial contractions (PACs)
D. Hypoplastic left heart syndrome (HLHS)
E. Anomalies of the branch pulmonary arteries
5. (C) Pulsed-wave Doppler of mitral valve inflow and aortic outflow can be used to assess irregular fetal rhythm (Figure 8.9). In addition, M-mode and TDI modalities can also be used to assess irregular fetal rhythm. PACs are the most common cause of fetal arrhythmia. Vascular ring, HLHS, d-TGA, and anomalies of the branch pulmonary arteries are best assessed using sweeps with 2D (grayscale) and color Doppler.
FIGURE 8.9 Pulsed-wave Doppler of AV valve inflow. Doppler demonstrates early premature atrial contraction (arrow).
6. Which is the most common fetal arrhythmia?
A. Premature atrial contractions (PACs)
B. Premature ventricular contractions (PVCs)
C. Supraventricular tachycardia (SVT)
D. Atrial flutter
E. Complete heart block
7. What is the normal range for fetal cardiothoracic area ratio?
B. 25% to 35%
C. 40% to 50%
D. 55% to 70%
7. (B) The normal fetal heart comprises about one-third of the fetal thorax, ranging from 25% to 35%.
8. Which form of critical CHD listed below is most likely to require an emergent postnatal cardiac intervention (surgery or catheterization) within hours of birth?
A. Coarctation of the aorta
B. Obstructed total anomalous pulmonary venous return (TAPVR)
C. Complete atrioventricular canal (CAVC) defect with pulmonary atresia
D. Tetralogy of Fallot (TOF) with pulmonary stenosis
E. Truncus arteriosus
8. (B) Obstructed TAPVR is still a surgical emergency because these patients cannot be fully stabilized with medical intervention alone. Due to the inability of blood to exit the lungs effectively and provide proper oxygen delivery to the body, these neonates are at risk for progressive hypoxia (cyanosis) and acidosis.
9. From the fetal Doppler interrogation in Figure 8.1, what interval is being measured between the parallel lines?
A. PP interval
B. RR interval
C. QT interval
D. PR interval
E. VA interval
10. While performing a fetal echocardiogram, you notice flow reversal across the ductus arteriosus. Which of the following defects is most likely to explain this finding?
C. Critical aortic stenosis
D. Total anomalous pulmonary venous connection
E. Pulmonary atresia with intact ventricular septum
10. (E) With lack of antegrade flow across the atretic pulmonary valve, fetuses with pulmonary atresia with intact ventricular septum often have reversal of flow across the ductus arteriosus into the hypoplastic main pulmonary artery and branch pulmonary arteries. The other listed congenital heart lesions all typically have a normally functioning pulmonary valve with antegrade flow into the main pulmonary artery and ductus arteriosus.
11. The normal fetal heart rate ranges from which of the following?
A. 80 to 120 bpm
B. 60 to 100 bpm
C. 100 to 180 bpm
D. 140 to 220 bpm
E. 100 to 140 bpm
12. What percentage of fetal cardiac output at term perfuses the lungs?
12. (A) At term, 10% of fetal cardiac output perfuses the lungs. The remainder of this deoxygenated blood is directed through the ductus arteriosus to the descending aorta and placenta for oxygenation.
13. The normal fetal cardiac axis is between which of the following?
A. 30 degrees and 60 degrees
B. 60 degrees and 90 degrees
C. 90 degrees and 150 degrees
D. 60 degrees and 180 degrees
E. 0 degrees and 90 degrees
13. (A) The normal leftward axis of the fetal heart (relative to the midline) ranges from 30 degrees to 60 degrees.
14. While performing a fetal echocardiogram, you notice retrograde flow into the aortic arch. Which of the following defects is most likely to explain this finding?
C. Critical aortic valve stenosis
D. Total anomalous pulmonary venous connection
E. Pulmonary atresia with intact ventricular septum
14. (C) Because of limited antegrade blood flow across the critically stenotic aortic valve, flow within the aortic arch is supplied retrograde from the ductus arteriosus. The other listed congenital heart lesions all typically have a normally functioning aortic valve with antegrade flow into the ascending aorta and transverse aortic arch and antegrade flow from the ductus arteriosus to the descending aorta.
15. Match the fetal teratogen and its most commonly associated fetal congenital heart lesion:
A. Ductal constriction
C. Coarctation of the aorta
D. Ebstein anomaly
2. Fetal alcohol syndrome
4. Fetal hydantoin syndrome
15. (1-D, 2-B, 3-A, 4-C, 5-E) Lithium has been shown in studies to be associated with fetal Ebstein anomaly as well as atrial septal defects and atrioventricular valve atresia. Fetal alcohol syndrome has been commonly associated with septal defects including atrial and ventricular septal defects and is less commonly associated with coarctation and conotruncal defects. Indomethacin is a potent ductal constrictor. Coarctation of the aorta and LVOT obstruction have been described in fetal hydantoin syndrome. Exposure to isotretinoin during gestation has been associated with fetal d-TGA as well as septal defects and conotruncal anomalies.
16. Which of the following congenital heart lesions should be excluded in the fetus with SVT?
A. Ebstein anomaly
B. Ventricular septal defect
C. Coarctation of the aorta
E. Complete AVSD
17. Which of the following forms of congenital heart disease is at greatest risk for needing emergent neonatal cardiac intervention and often requires a highly coordinated delivery at a tertiary care hospital to ensure immediate access to cardiac treatment?
A. Tetralogy of Fallot with pulmonary stenosis
B. Hypoplastic left heart syndrome (HLHS) with restrictive atrial septum
C. Complete atrioventricular canal defect
D. Coarctation of the aorta
E. Double-outlet right ventricle
17. (B) HLHS with restrictive atrial septum. In HLHS, there is often mitral and/or aortic atresia such that blood cannot exit the left heart. Therefore, HLHS requires an adequate atrial communication to allow the blood to exit the left atrium and join the rest of the circulation to the body. If there is not an adequate atrial communication, these patients can present like obstructed TAPVR due to back up of blood into the lungs resulting in severe pulmonary congestion, worsening hypoxia, and acidosis. These infants are often critically ill at birth and require either emergent opening of the atrial septum via catheterization or surgical septectomy.
18. A mother has a fetal echo at 24-week gestation that reveals the diagnosis shown below (Figure 8.2). After counseling the family on the diagnosis, you explain that postnatal management of their newborn will include which of the following immediately after birth:
A. Balloon atrial septostomy
B. PGE infusion
E. Central venous line placement
18. (B) PGE infusion. This image shows a fetus with HLHS of the mitral atresia and aortic atresia variety. There is a single RV that has enlarged to take over the apex of the heart. The RA and LA are also seen with a wide-open atrial communication between them such that this child does not appear to be at risk for restrictive atrial septum, so a balloon atrial septostomy or immediate surgery should not be warranted. PGE infusion is indicated to maintain ductal patency for systemic blood flow and can be given through a peripheral IV, so placement of a central venous line is not always necessary. PGE causes the side effect of apnea in ˜50% of babies so intubation may be necessary, but not in all patients. Therefore, PGE1 is the only therapy that needs to be started in this patient with 100% certainty, shortly after birth.
19. In specific cases of CHD, there can be additional concerns during the pregnancy. Progression of heart disease or associated comorbidities are often of great concern and need to be monitored closely during the second and third trimesters. For the fetal diagnosis pictured below (Figure 8.3), what is of greatest concern for the fetus during the remainder of the pregnancy:
B. Supraventricular tachycardia
C. Growth restriction
19. (A) Hydrops. This image depicts a fetus with Ebstein anomaly (EA) as noted by the inferiorly displaced tricuspid valve leaflets, severe RA, and RV dilation with massive cardiomegaly (wall-to-wall heart). EA fetuses can develop all the problems listed above, but the highest risk and one of the greatest concerns is hydrops because it can lead to fetal demise. Development of hydrops and/or fetal demise has been reported in up to 45% of fetal EA cases. Rhythm disturbances have been reported in up to 17% of EA fetuses, with the most common being SVT. Growth restriction and prematurity also occur more frequently in EA and must be monitored closely. Polyhydramnios can be part of the constellation of hydrops and can also increase the risk for prematurity.
20. A fetal echocardiogram performed at 24 weeks EGA confirmed the diagnosis of congenital heart disease with no evidence of heart failure. There was normal fetal heart size, heart function, valve function, and heart rate and rhythm. For the diagnosis pictured below (Figure 8.4), what complicating condition needs to be monitored for during the remainder of gestation:
A. Supraventricular tachycardia
B. Growth restriction
D. Heart block
20. (D) Heart block. The diagnosis pictured is congenitally corrected transposition of the great arteries (ccTGA). Note that the left-sided ventricle has a lower attachment of the AV valve which is the tricuspid valve, has a moderator band across the apex, and is more trabeculated because it is the morphologic RV. By comparison, the more anterior and rightward ventricle has a higher-inserted AV valve which is the mitral valve, smooth-walled septum with no AV valve attachments, and bullet chamber with no moderator band. Not pictured here are the outflow tracts which are usually oriented in an L-TGA configuration with the aorta arising anterior and leftward from the left-sided RV and the pulmonary artery arising posterior and rightward to the aorta from the right-sided LV. There are often associated heart defects in ccTGA, such as VSD, pulmonary stenosis, and tricuspid valve abnormalities which can be seen in up to 80% of cases. Growth restriction, hydrops, and polyhydramnios are unlikely to occur in cases of ccTGA unless there is associated extracardiac disease, a genetic syndrome, or fetal CHF (in this case it was noted that the heart function and valve function were normal). SVT is rarely noted to occur in ccTGA, but heart block is a well-known risk due to the abnormal position of the AV node and bundle of His which can lead to early fibrosis. Up to 20% of fetuses with ccTGA have been reported to have varying degrees of AV block and associated bradycardia. If complete heart block develops, this can put the fetus at risk of developing hydrops if the ventricular escape rate is very slow. This would also change the delivery management.
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