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RA RV
LA LV
Chapter 37 ■ The Fetal Heart 1307
A
RV RA
LV LA
B
C
FIGURE 37-21. Foraminal flap and foramen ovale. A, Linear appearance of the foraminal flap (arrow) as it enters the left
atrium, LA. B, Circular appearance of the foraminal flap (arrow) entering the left atrium. C, Color Doppler ultrasound subcostal fourchamber view shows normal flow through the foramen ovale; LV, left ventricle; RA, right atrium; RV, right ventricle.
A-V canal defects. Almost two thirds of fetuses with
AVSD have additional cardiac anomalies.
62-64
About one
third are associated with left atrial isomerism (both atria
anatomically resemble the left), and of these the majority
have complete heart block.
trisomy 21) or extracardiac anomalies are associated in
78% of AVSDs.
61
61,62
Chromosomal (especially
Embryologically, in the primitive heart, the common
atrium and ventricle communicate through the A-V
canal. Development of the endocardial cushion results
in division of the single, large A-V canal into two separate orifices, separating the atria from the ventricles (Fig.
37-25). The interatrial and interventricular septa develop
concurrently, eventually dividing the single atrium and
ventricle into right and left portions. When the endocardial cushions fail to fuse properly, normal development
of the mitral and tricuspid valves cannot occur, and an
AVSD results (Fig. 37-26).
Atrioventricular septal defects are divided into com-
plete and partial or incomplete forms.
65
In both, the A-V
valves are abnormal. In the complete type a single, multileaflet valve is present, whereas in the incomplete form,
two of the leaflets (bridging leaflets) are connected by a
narrow strip of tissue, resulting in the appearance of two
valve orifices. Complete AVSD has variable amounts of
deficient tissue in the atrial and ventricular septa. The
incomplete form is associated with an ostium primum
ASD. At fetal echocardiography, 97% of AVSDs are
complete, although after birth only 69% are com-
57,61
plete.
greater than that in the live-born population, indicating
a high incidence of in utero demise.
The fetal incidence of AVSD is four times
36,37,66
1308 PART IV ■ Obstetric Sonography
RA
LA
FIGURE 37-22. Four-chamber view shows an ostium primum
atrial septal defect (arrow) in a fetus with an atrioventricular
septal defect; LA, left atrium; LV, left ventricle; RA, right atrium;
RV, right ventricle.
Tricuspid
valve
FIGURE 37-23. Interventricular septum viewed
from right ventricle. The membranous septum and the
three portions of the muscular septum (inlet, outlet, and trabecular) are demonstrated. Ventricular septal defects may occur in any
of these locations.
RV
LV
Pulmonary valve
Outlet
Membranous
TrabecularInlet
Atrioventricular septal defects are considered bal-
anced when the A-V junction is connected to both the
right and the left ventricle, such that blood flow is relatively evenly distributed. If this connection exists with
primarily one ventricle, such as in the setting of a hypoplastic left ventricle, it is termed an unbalanced AVSD.
Sonographically, a defect in the atrial or ventricular
septum with an associated single abnormal A-V valve is
seen in a four-chamber view (Fig. 37-27). The defect is
better visualized in diastole than in systole. The abnormal valve should be suspected when the normal offset
of the A-V valves is not visualized. Demonstration of
two A-V valve orifices allows for differentiation between
complete and incomplete forms of AVSD.
52
LA
RA
FIGURE 37-24. Muscular ventricular septal defect
(VSD). Subcostal four-chamber color Doppler ultrasound view
shows a muscular VSD (arrow) across the interventricular septum
(S); RA, right atrium; RV, right ventricle; LA, left atrium; LV, left
ventricle.
LV
S
RV
Color Doppler ultrasound demonstrates an open area
of flow across the atrioventricular septal defect and the
abnormal A-V valve. Color Doppler ultrasound imaging
is particularly useful in the detection of valvular insufficiency.
associated with fetal hydrops and a worsening prognosis.
be identified across the ostium primum defect before the
onset of holosystolic valvular insufficiency.
67
Holosystolic valvular insufficiency is closely
68
Frequently, a left ventricular–to–right atrial jet can
29
Cardiac
malformations associated with AVSD include septum
secundum ASD, hypoplastic left heart syndrome, valvular pulmonary stenosis, coarctation of the aorta, and
tetralogy of Fallot. A recent meta-analysis of published
cases of AVSD diagnosed prenatally confirms that chromosomal anomalies are common, occurring in 25% to
58% of affected fetuses.
69
Therefore, karyotyping is indicated. Associated extracardiac anomalies are common,
including omphalocele, duodenal atresia, tracheoesophageal atresia, facial clefts, cystic hygroma, neural tube
defects, and multicystic kidneys.
69
The fetus with AVSD and associated defects has a
poor prognosis. When hydrops is present, few survive
the neonatal period.
70
Despite advances in pediatric cardiothoracic surgery, the overall outcome for antenatally
diagnosed AVSD remains poor, with most studies
reporting 5-year to 15-year survival rates well below
69
50%.
Ebstein Anomaly
Ebstein anomaly is characterized by inferior displacement of the tricuspid valve, frequently with tethered
attachments of the leaflets, tricuspid dysplasia, and right
Chapter 37 ■ The Fetal Heart 1309
4 wks
Septum primum Septum secundum
Atrioventricular
canal
Endocardial
cushion
Common ventricle
Interventricular
septum
A B
8 wks
Septum secundum
Ostium secundum
Septum primum
Mitral valve
C
Tricuspid valve
5 wks
Ostium secundum
Septum primum
fused to
endocardial cushions
Fused endocardial
cushions
Interventricular
septum
FIGURE 37-25. Normal development of endocardial cushions. A, In the fourth week the endocardial cushions divide
the atrioventricular canal into two orifices. B, By the fifth week the communication between the atria, the ostium secundum, is smaller.
The ventricular septum has grown, almost obliterating the communication between the ventricles. C, At 8 weeks, complete development
of the endocardial cushions and atrioventricular valves results in four distinct cardiac chambers.
Normal tricuspid and mitral valves
Antero-superior
A B
Antero-superior
leaflet
Inferior leaflet
Septal leaflet
Complete atrioventricular septal defect
Right mural
leaflet
leaflet
Tricuspid
valve
RT
Mitral
valve
LT
C
Aortic leaflet
Mural leaflet
Anterior
bridging leaflet
Left mural
leaflet
Posterior
bridging leaflet
Partial atrioventricular septal defect
RT
LT
“Cleft”
FIGURE 37-26. Valve leaflet morphology. A, Normal heart. B, Partial atrioventricular septal defect (AVSD). C, Complete
AVSD.
71-75
ventricular dysplasia
(Fig. 37-28). Ebstein anomaly
makes up approximately 7% of cardiac anomalies in the
fetal population and has an incidence of 0.5% to 1% in
high-risk populations.
per 20,000 live births.
54,76,77
It occurs in approximately 1
78
Early data from biased retrospective studies suggested
that lithium use during pregnancy was associated with
an estimated 500-fold increase in the incidence of
Ebstein anomaly in exposed fetuses.
that the increased risk is no more than 28% and may be
nonexistent.
84
Ebstein anomaly may be associated with
78-83
It is now clear
a variety of structural cardiovascular defects, particularly
pulmonary atresia or stenosis,85 arrhythmias, and
chromosomal anomalies.
Ebstein anomaly is readily detected in utero.
73,86-89
86,90
The
sonographic diagnosis rests on recognition of apical displacement of the tricuspid valve into the right ventricle,
an enlarged right atrium containing a portion of the
“atrialized” right ventricle, and a reduction in size of the
functional right ventricle. Differential diagnosis includes
tricuspid valvular dysplasia, Uhl anomaly, and idiopathic
right atrial enlargement, but none of these has an inferiorly displaced tricuspid valve, the most reliable sign of
Ebstein anomaly. Ebstein anomaly is one of the few
1310 PART IV ■ Obstetric Sonography
RA LA
RA LA
RV LV
A
FIGURE 37-27. Atrioventricular septal defect (AVSD). A, Apical four-chamber view shows absent atrial septum, resulting
in a single, large atrium (RA-LA). A VSD is seen between the left ventricle (LV) and right ventricle (RV). A single, multileaflet atrioventricular valve is also appreciated. B, Apical four-chamber color Doppler ultrasound view shows the atrioventricular septal defect.
Ebstein anomaly
RA LA
Mitral
valve
Tricuspid
valve
B
RV LV
RV
LV
RA
LA
Anterior
A
FIGURE 37-28. Ebstein anomaly. A, Tricuspid valve is apically displaced, resulting in an enlarged atrium and a small, functional
right ventricle. B, Gray-scale image shows tricuspid valve (arrows) displaced inferiorly, resulting in an “atrialized” right ventricle (RV) and
enlarged right atrium (RA); LV, left ventricle; LA, left atrium.
structural defects that may cause substantial cardiac
dysfunction in utero, frequently with cardiomegaly,
hydrops, and tachyarrhythmias.
73
Examination with
spectral and color Doppler ultrasound is helpful in demonstrating tricuspid valve regurgitation, which causes
further enlargement of the right atrium and ventricle.
Tethered distal attachments of the tricuspid valve,
marked right atrial enlargement, and left ventricular
B
compression with narrowing of the pulmonary outflow
tract are all associated with a poor prognosis.
73
Arrhythmias, particularly supraventricular tachycar-
dias, are common with Ebstein anomaly and can further
91
compromise the fetus. Overall, the 3-month mortality
rate of patients diagnosed in utero is 80%.
73,90
Surgical
correction of Ebstein anomaly in young children is associated with a low mortality and an excellent quality of
Chapter 37 ■ The Fetal Heart 1311
92-94
Because clinical presentation, treatment options,
life.
and prognosis are inconsistent, case-by-case management is variable.
95
Hypoplastic Right Ventricle
Hypoplastic right ventricle generally occurs secondary to
pulmonary atresia with intact interventricular septum.
It has an incidence of 1.1% among stillbirths.
pid atresia may be associated with a hypoplastic right
ventricle but this is not as common.
96
Pathophysiologi-
36
Tricus-
cally, hypoplasia of the right ventricle develops because
of a reduction in blood flow secondary to inflow impedance from tricuspid atresia or outflow impedance from
pulmonary arterial atresia. Typical sonographic findings
include a small, hypertrophic right ventricle and a small
or absent pulmonary artery
96
(Fig. 37-29). Pulsed
Doppler ultrasound may be helpful in demonstrating
decreased flow through the tricuspid valve or pulmonary
artery. Congestive heart failure and hydrops may develop
from tricuspid regurgitation. After birth, closure of the
ductus arteriosus frequently results in neonatal death.
Prognosis improves with preoperative prostaglandin
infusion to maintain the patency of the ductus.
97
atresia, aortic stenosis, and mitral valve atresia. It is associated with coarctation of the aorta in 80% of cases.
100
The primary sonographic feature of HLHS is a small left
ventricle (Fig. 37-30). The mitral valve is typically hypoplastic or atretic, as is the aorta.
101
Color Doppler ultrasound is extremely helpful in the setting of HLHS,
usually demonstrating the absence of flow through the
mitral and aortic valves.
30
This syndrome has an extremely poor prognosis, with
25% mortality in the first week of life, and untreated
infants dying within 6 weeks.
102
Prenatal diagnosis
of HLHS is beneficial for preventing ductal shock
and keeping affected infants stable in the preoperative
103-105
stage.
Monophasic blood flow across the mitral
valve, restricted flow through the foramen ovale, and
retrograde flow through the aorta are all considered poor
prognostic signs in utero. Despite significant advancements in medical-surgical management over the past
20 years, follow-up studies demonstrate that HLHS
children often experience major developmental delays
and decreased exercise performance, even after heart
transplantation.
107
106
Univentricular Heart
Hypoplastic Left Heart Syndrome
In hypoplastic left heart syndrome (HLHS), the left
ventricular cavity is pathologically reduced in size. HLHS
constitutes approximately 7% to 9% of all congenital
cardiac lesions.
recurrence risk of 0.5%.
98
It has a 2:1 male predominance and a
98,99
The small left ventricle
results from decreased blood flow into or out of the
left ventricle. The primary abnormalities include aortic
RV LV
LARA
In univentricular heart, two atria empty into a single
ventricle, via two A-V valves or a common A-V valve.
Univentricular heart is rare, accounting for approximately 2% of CHD.
37
It results from a failure of
the interventricular septum to develop. The single
chamber has a left ventricular morphology in 85% of
108
cases.
Associated cardiac anomalies are common,
with asplenia or polysplenia occurring in 13%.
109
110
Sonographically, a single ventricle with absence of the
RV
LV LA
RA
SP
SP
FIGURE 37-29. Hypoplastic right ventricle. Apical
four-chamber view shows small, right ventricular chamber (RV);
RA, right atrium; LV, left ventricle; LA, left atrium; SP, spine.
FIGURE 37-30. Hypoplastic left heart syndrome.
The left atrium (LA) and left ventricle (LV) are small; RA, right
atrium; RV, right ventricle; SP, spine.
1312 PART IV ■ Obstetric Sonography
interventricular septum is seen. Doppler ultrasound
examination is helpful in determining if a normal outflow
tract is present. A nonfunctioning, rudimentary accessory ventricle may be present in some cases. Differential
diagnosis includes a large VSD and hypoplastic right or
left ventricle.
Patients with outflow tract stenosis have a poorer
prognosis.
heart failure or arrhythmia.
111
Death is typically caused by congestive
66
Pulmonary artery banding
and shunts yield a 70% 5-year survival rate. Ventricular
septation has a postoperative survival rate of approximately 56%.
109,112
Tetralogy of Fallot
Tetralogy of Fallot consists of (1) VSD, (2) overriding
aorta, (3) hypertrophy of the right ventricle, and (4)
stenosis of the right ventricular outflow tract (Fig. 37-31;
Video 37-9). It accounts for 5% to 10% of CHD in live
36
and is associated with a variety of cardiac and
births
extracardiac abnormalities and chromosomal anoma-
61
A recent study of 129 fetuses diagnosed in utero
lies.
with tetralogy of Fallot reported additional cardiac
anomalies in 57%, extracardiac anomalies in 50%, and
chromosomal anomalies in 49%. The nuchal translucency was above the 95th centile in 47% of fetuses.
113
Tetralogy of Fallot occurs when the conus septum is
located too far anteriorly, thus dividing the conus into a
smaller, anterior right ventricular portion and a larger
posterior part. Closure of the interventricular septum is
incomplete, causing the aorta to override both ventri-
114
The VSD typically occurs in the perimembranous
cles.
portion of the septum. Right ventricular hypertrophy
rarely occurs in utero, but the overriding aorta is reliably
115,116
seen.
Pulmonary atresia or stenosis, or a dilated
pulmonary artery secondary to absence of the valve, may
be appreciated. The diagnosis of tetralogy of Fallot has
RV
AO
IVS
LV
been made before 15 weeks’ gestation using transvaginal
ultrasound.
making the diagnosis of tetralogy of Fallot.
24
Color Doppler imaging is helpful in
117
The newborn with the classic form of tetralogy of
Fallot who has pulmonary stenosis rather than pulmonary atresia is generally asymptomatic at birth but develops cyanosis and a murmur in the first weeks of life.
Typical cases of tetralogy of Fallot are repaired at 4 to 6
months of age, with close to 90% survival at 1 year.
Patients surviving early surgery (before 5 years old) have
a 32-year survival of 90%.
heart failure in the fetus or newborn is associated with
17% to 41% mortality.
119
The presence of congestive
120,121
118
Truncus Arteriosus
Truncus arteriosus accounts for 1.3% of fetal cardiac
anomalies and is characterized by a single large vessel
arising from the base of the heart. This vessel supplies
the coronary arteries and the pulmonary and systemic
circulations. Aortic anomalies occur in 20% and noncardiac anomalies in 48% of patients with truncus arterio-
122
In almost all cases, a VSD is present. The truncal
sus.
valve may have two to six cusps and generally overrides
the ventricular septum. Four types of truncus arteriosus
have been identified by Collett and Edwards,
123
as
follows:
• Type I has a pulmonary artery that bifurcates into
right and left branches after it arises from the
ascending portion of the truncal vessel.
• Type II has right and left pulmonary arteries arising
separately from the posterior truncus.
• Type III has pulmonary arteries that arise from the
sides of the proximal truncus.
• Type IV has systemic collateral vessels from the
descending aorta as the source of flow.
The single, large truncal artery with overriding of the
ventricular septum and an associated VSD is identified
on four-chamber and outflow tract views (Fig. 37-32).
This anomaly has been diagnosed before 15 weeks’ gestation with transvaginal ultrasound.
24
Color Doppler
imaging is particularly helpful in the setting of truncus
arteriosus because it facilitates accurate localization of the
pulmonary arteries and rapidly detects truncal valvular
insufficiency. In the past, prognosis was poor, with an
overall mortality of 70%.
122
More recent studies indicate
that 10-year to 20-year survival and level of function
are excellent for infants undergoing complete repair of
truncus arteriosus.
124
33
FIGURE 37-31. Tetralogy of Fallot. The aorta (AO) over-
rides both the right ventricle (RV) and the left ventricle (LV). A
ventricular septal defect (arrows) is also appreciated. IVS, Interventricular septum.
Double-Outlet Right Ventricle
Double-outlet right ventricle (DORV) represents less
than 1% of all CHD and occurs when more than 50%
of both the aorta and the pulmonary artery arise from
the right ventricle.
125,126
DORV is classified into the fol-
lowing three types:
Chapter 37 ■ The Fetal Heart 1313
RV
PA
RV
TA
LV
SP
FIGURE 37-32. Truncus arteriosus. The single truncal
artery (TA) overrides both the right ventricle (RV) and left ventricle (LV). A ventricular septal defect (arrow) is present. No
pulmonary artery was seen, helping to differentiate from tetralogy
of Fallot. SP, Spine.
• Aorta posterior and to the right of the pulmonary
artery.
• Aorta and pulmonary artery parallel, with the aorta
to the right (Taussig-Bing type).
• Aorta and pulmonary artery parallel, with the aorta
anterior and to the left.
Double-outlet RV is associated with other cardiac
defects (particularly VSD), various extracardiac defects,
fetal chromosomal anomalies, maternal diabetes, and
maternal alcohol consumption.
intervention, 10-year survival is up to 97%.
3,126,127
With surgical
125
When
extracardiac or chromosomal anomalies are present,
prognosis is poor, with 69% mortality when the diagnosis of DORV is made in utero.
127
Sonographically, the
aorta and pulmonary artery arise predominantly from
the right ventricle (Fig. 37-33). Differential diagnosis
includes transposition of the great vessels and tetralogy
of Fallot.
Transposition of Great Arteries
Transposition of the great arteries (TGA) is subdivided
into two types: (1) complete or dextrotransposition
(D-TGA) in 80% and (2) congenitally corrected or
levotransposition (L-TGA) in 20% of fetuses with
transposition. In both types, ventriculoarterial (V-A)
discordance is present (aorta arises from right ventricle,
AO
FIGURE 37-33. Double-outlet right ventricle. The
aorta (AO) and pulmonary artery (PA) both arise from the right
ventricle (RV) in a parallel fashion.
A
P
FIGURE 37-34. Complete transposition of great
arteries. The aorta (A) is anterior to the pulmonary artery (P).
This abnormal arrangement results in both vessels running parallel
to each other in this short-axis view.
and pulmonary artery arises from left ventricle). Com-
plete transposition (D-TGA) is defined as A-V concordance (atria and ventricles are correctly paired) with V-A
discordance (Fig. 37-34). It comprises 5.5% of heart
disease in the fetal population.
37
D-TGA is also classified
into two types, depending on the absence (70%) or presence of a VSD. A variety of cardiac anomalies are associated with D-TGA, including pulmonic stenosis, which
rarely occurs in the absence of a VSD. In 8% of cases,
1314 PART IV ■ Obstetric Sonography
other organ systems are involved. Chromosomal anomalies are not associated with TGA.
In D-TGA, the aorta arises from the right ventricle,
receives systemic blood, and returns it to the systemic
circulation. The pulmonary artery arises from the left
ventricle, receives pulmonary venous blood, and returns
it to the lungs. Generally, the aortic root lies anterior and
slightly to the right of the pulmonary outflow tract. With
closure of the ductus arteriosus and foramen ovale after
birth, this condition is incompatible with life unless an
associated shunt allows mixing of the separate right and
left circulations.
Sonographic diagnosis depends on demonstrating that
the great vessels exit the heart in parallel, rather than
crossing in normal fashion. This is optimally seen in a
long-axis or short-axis view of the great vessels. A threevessel view is also useful because only one great vessel
(aorta) is usually visualized at this level, in this setting.
Most neonates with D-TGA require immediate
treatment. Initially, a temporizing shunt is created
before definitive treatment. With surgical intervention,
12-month survival can be expected in 80%.
128
Corrected transposition (L-TGA) is characterized
by A-V discordance with V-A discordance (Fig. 37-35).
It comprises 1% of CHD and 20% of cases of fetal
37
The aorta, which arises from the left sided,
TGA.
morphologic right ventricle, is anterior and to the left
of the pulmonary artery. The pulmonary artery arises
from the right sided, morphologic left ventricle. VSD
and pulmonic stenosis occur in approximately half the
108,129
cases.
Malformation and inferior displacement of
the morphologic tricuspid valve may be present.
RV
LV
LA RA
FIGURE 37-35. Congenitally corrected transposi-
tion of great arteries. An apical four-chamber view shows
the morphologic right ventricle (RV) and morphologic left ventricle (LV) located on the incorrect sides of the heart. This is
evidenced by identifying the atrioventricular valve leaflet insertion
(arrow) on the left side of the heart in a more apical location than
the right-sided atrioventricular valve leaflet insertion.
Pathophysiologically, the flow of blood through the
heart to the pulmonic and systemic circulations is
normal, even though the morphologic right ventricle is
on the left and the morphologic left ventricle is on the
right.
The antenatal sonographic diagnosis hinges on demonstrating a parallel arrangement to the great vessels,
similar to D-TGA. Differentiating D-TGA from L-TGA
entails identification of the morphologic right and left
ventricles. The moderator band will be seen on the
anatomic left side. Additionally, the tricuspid valve will
be situated on the anatomic left side, so its more apical
septal leaflet should be identified. Associated cardiac
defects are common and diverse, including VSD, pulmonary stenosis/atresia, ASD, DORV, tricuspid valve
anomalies, dextrocardia, mesocardia, and situs inversus.
Fetal A-V block is also common.
130
In the absence of associated cardiac anomalies, patients
with corrected TGA may remain asymptomatic throughout their lives.
Anomalous Pulmonary
Venous Return
Anomalous pulmonary venous return can be divided
into two subgroups: total anomalous pulmonary
venous return (TAPVR), in which none of the pulmonary veins drains into the left atrium, and partial anom-
alous pulmonary venous return (PAPVR), in which at
least one of the pulmonary veins has an anomalous connection. TAPVR constitutes 2.3% of cases of CHD.
131,132
The four types of anomalous pathways are as follows:
1. The pulmonary veins drain into a vertical vein that
empties into the innominate vein and then into the
superior vena cava.
2. The pulmonary veins drain into the coronary sinus
and then into the right atrium.
3. The pulmonary veins drain directly into the right
atrium.
4. The pulmonary vein drains into the portal vein and
into the inferior vena cava via the ductus venosus.
Embryologically, TAPVR is thought to result from
failure of obliteration of the normal connections between
the primitive pulmonary vein and the splanchnic, umbilical, vitelline, and cardinal veins. TAPVR is associated
with AVSDs, polysplenia, and asplenia syndromes.
The antenatal sonographic diagnosis of TAPVR
is difficult because the anomalous veins are generally
extremely small and variable in their course. Often the
first sign of APVR is mild right ventricular and pulmonary artery prominence, in which case a careful
search for the four normal pulmonary veins should be
undertaken. This can be difficult because the two inferior pulmonary veins are usually more difficult to visualize than the two superior veins, even in a normal fetal
heart. Color and spectral Doppler ultrasound are helpful
in documenting the normal pulmonary venous anatomy
LV
Chapter 37 ■ The Fetal Heart 1315
RA
RV
LA
LV
RV
RA
A
FIGURE 37-36. Normal pulmonary venous anatomy. A, Four-chamber color Doppler ultrasound view shows two superior
pulmonary veins (P) entering the left atrium (LA). B, Subcostal four-chamber view using pulsed Doppler ultrasound shows normal waveform and direction of pulmonary venous flow into the left atrium. LV, left ventricle; RA, right ventricle; RV, right ventricle; S, systolic
peak; D, diastolic peak.
LA
P
P
D S D S D S D S
B
and in detecting and following the anomalous connections (Fig. 37-36). Spectral Doppler imaging is used to
evaluate blood flow across the A-V valves or aortic and
pulmonic valves. A ratio of right flow/left flow greater
than 2 : 1 is highly suspicious for TAPVR.
The diagnosis of TAPVR is suspected when no pul-
133
RVLV
monary veins are seen entering the left atrium (Fig.
37-37). A small left atrium resulting from decreased
blood return and lack of normal incorporation of the
common pulmonary vein into the left atrium is also suggestive of TAPVR. Approximately one third of patients
with TAPVR have variable associated cardiac anoma-
134
Right atrial isomerism is common. Associated
lies.
extracardiac anomalies include gut malrotation and
midline liver and stomach.
135,136
TAPVR causes minimal
LA RA
P
P
P
P
hemodynamic disturbance in utero, although hydrops
occasionally results. Left untreated, the majority of
infants die before 1 year of age.
been diagnosed in utero, PAPVR is more difficult
and can only be diagnosed when pulmonary veins are
seen entering the left atrium as well as the right atrium
or an accessory pathway to the right atrium.
134
Although it has also
137
APVR is
FIGURE 37-37. Total anomalous pulmonary venous
return. Apical four-chamber view shows anomalous insertion of
all four pulmonary veins (P) into the right atrium (RA); RV, right
ventricle; LA, left atrium; LV, left ventricle.
associated with a high morbidity and mortality, largely
because of the high incidence of additional cardiac
anomalies.
135,137
Coarctation of Aorta
Coarctation is a narrowing of the aortic lumen, usually
occurring between the insertion of the ductus arteriosus
and the left subclavian artery. Its severity ranges from
a slight narrowing at the distal end of the arch to
severe hypoplasia of the entire arch. Coarctation has an
incidence of 6% prenatally.
37
Almost 90% of the cases
are associated with other cardiac anomalies, including
abnormal aortic valve (bicuspid or stenotic), VSD,
DORV, and AVSD. Chromosomal abnormalities occur
1316 PART IV ■ Obstetric Sonography
FIGURE 37-38. Coarctation of aorta. Spectral Doppler
tracing shows increased velocity through the aortic arch.
in 5%, and almost 5% of coarctations are associated with
maternal diabetes.
49,138
Three embryologic theories have been proposed to
explain the origin of coarctation of the aorta: (1) a
primary developmental defect with failure of connection
of the fourth and sixth aortic arches with the descending
139
aorta;
aortic arch;
the aortic isthmus.
(2) aberrant ductal tissue at the level of the
140,141
and (3) decreased blood flow through
142
Sonographic detection of coarctation is difficult.19
Ventricular size discrepancy with a prominent right ventricle and relatively small left ventricle,
to-left ventricle diameter ratio greater than 2 standard
deviations (SD) above the norm,
45,142
with a right-
143,144
suggests coarctation of the aorta. Likewise, a discrepancy in pulmonary
artery–to–ascending aorta diameter that falls greater
than 2 SD above the normal ratio of 1.18 to 0.06
is suggestive of coarctation.
143
Color Doppler ultrasound
144
is useful in identifying the area of narrowing. Spectral
Doppler ultrasound may detect increased flow distal to
the narrowed segment (Fig. 37-38). Many coarctations
do not become evident until closure of the ductus arteriosus at birth. Additionally, infants with coarctation of
the aorta may not develop clinical or echocardiographic
signs of coarctation until 6 to 12 weeks after closure of
the ductus arteriosus. If coarctation of the aorta is suspected on fetal echocardiogram, the infant should be
followed to at least 1 year of age.
coarctation has a good prognosis, 39% mortality is
reported when associated anomalies are present.
145
Although isolated
146
Aortic Stenosis
occurs above the sinuses of Valsalva and is associated
with William’s syndrome. Valvular aortic stenosis is
more frequent in males and associated with a bicuspid
aortic valve and chromosomal abnormalities.
vular aortic stenosis is associated with inherited disorders, asymmetrical septal hypertrophy (ASH), and
hypertrophic obstructive cardiomyopathy. Infants of
diabetic mothers may have a transient form of left ventricular outflow tract obstruction secondary to ASH.
The supravalvular type of aortic stenosis has not been
reported in utero. Thickening of the aortic valve, poststenotic dilation of the aorta, and ventricular enlargement are clues to valvular aortic stenosis. Thickening of
the interventricular septum may be seen in subvalvular
aortic stenosis. In all cases, increased velocity through the
aortic valve will be identified on pulsed Doppler ultrasound. Early-onset aortic stenosis results in endocardial
fibroelastosis and hypoplastic left ventricle.
Aortic stenosis progresses in utero and may not be
apparent on early (<16 weeks) fetal echocardiograms.
In some cases these defects may not be apparent until
after birth.
life is reported with aortic stenosis.
improved with appropriate surgery, with mortality
between 1.9% and 9%.
149
A mortality rate of 23% in the first year of
151,152
In cases of critical aortic
150
Prognosis has
stenosis, in utero balloon valvoplasty has been attempted.
Technical success has been achieved in many cases, along
with reduced sequelae. However, long-term follow-up is
not yet available.
153
Pulmonic Stenosis
Pulmonic stenosis may occur at the valve level or at the
infundibulum. It occurs in 7.4% of newborns.
plastic and stenotic pulmonic valves are seen in Noonan
syndrome and with maternal rubella. Pulmonic stenosis is associated with TAPVR, ASD, supravalvular aortic
stenosis, and tetralogy of Fallot. Pulmonic stenosis
can occur in the recipient twin of a pregnancy affected
with twin-twin transfusion syndrome. In this setting the
recipient’s heart becomes hypertrophic secondary to
increased preload. This is similar to the ASH present in
fetuses of diabetic mothers and results in anatomic
obstruction of the outflow tract.
148
Increased velocity through the pulmonic valve and
hypertrophy of the right ventricle suggest pulmonic stenosis. As with aortic stenosis, pulmonic stenosis tends
to progress in utero. Pulmonic stenosis has a variable
outcome and can be managed with closed transventricular valvotomy or percutaneous balloon valvoplasty.
In utero pulmonary balloon valvuloplasty has also been
attempted but is still in its early phase.
155
147
148
Subval-
36
Dys-
154,155
Aortic stenosis is a stricture or obstruction of the ventricular outflow tract occurring in 5.2% of newborns.
36
Aortic stenosis is divided into supravalvular, valvular,
and subvalvular types. Supravalvular aortic stenosis
Cardiosplenic Syndrome
Cardiosplenic syndromes are syndromes associated
with asplenia (right isomerism) and polysplenia (left
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