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Color Doppler Ultrasound in Fetal Echocardiography
Fig. 22.6a Site of entry of the superior vena cava (SVC) and inferior
vena cava (IVC) into the right atrium (RA), with the spine above.
RV =right ventricle.
22
Fig. 22.7a Junction of the superior vena
cava (SVC) with the right atrium (RA).
Next to the vena cava is the ascending
aorta (AO), which arises from the left
ventricle (LV). The scan plane also cuts
the pulmonary artery (PA) just in front of
the aorta.
Fig. 22.7b Color Doppler image in the
same plane as a. The blood flow from the
superior vena cava into the right atrium is
encoded in blue, while flow in the ascending aorta and pulmonary artery is
encoded in red.
a
Fig. 22.6b Color Doppler image of superior vena cava flow. The typi-
cal Doppler spectrum displays two peaks representing ventricular systole (S) and diastole (D). Flow is decreased during atrial systole (앖).
b
202
Fig. 22.8a Site of entry of the ductus venosus (DV) into the inferior
vena cava (IVC) just before its entry into the right atrium. Color Doppler demonstrates the parallel arrangement of the two blood flows. The
blood in the ductus venosus is encoded in yellow.
Fig. 22.8b Typical Doppler spectrum of the ductus venosus, showing
a systolic and diastolic peak and a reduction in flow during atrial contraction.
Ultrasound Examination of the Fetal Heart
Fig. 22.9a Long-axis view of the heart. The right ventricle (RV) is
anterior. The posterior chambers are the left atrium (LA) and left ven-
tricle (LV), from which the aorta (AAo) arises.
Fig. 22.9b Rotating the transducer clockwise demonstrates the
origin of the pulmonary artery (PA) from the right ventricle (RV). The
pulmonary artery “crosses” the aorta in this projection. The ductus
arteriosus (DA) connects the pulmonary artery to the descending
aorta (DAO) via the ductal arch. Below the aorta is the fetal spine.
Specific Obstetric Problems
Fig. 22.10 a The ductal arch (with the fetal spine above). The pulmonary artery (PA), ductus arteriosus (DA), and descending aorta (DAO)
are in direct continuity. In front of the descending aorta is the right
ventricle (RV), from which the pulmonary artery arises. The ductus
arch is broad and does not give rise to any brachiocephalic vessels.
Fig. 22.10 b Color Doppler image in the same plane. The sample
volume is placed first in the ductus arteriosus (DA, left spectrum) and
then more proximallyin the pulmonary trunk (PT, right spectrum). The
ductus arteriosus exhibits a higher flow velocity with a brief early dias-
tolic dip followed by low diastolic flow.
203
Color Doppler Ultrasound in Fetal Echocardiography
Position of the Fetal Heart in Abdominal and
Thoracic Scans
Horizontal transverse scan. The position of the abdominal
aorta and inferior vena cava is evaluated in the horizontal
transverse scan. The descending aorta runs anterior to the spi-
nal column on the left side, the inferior vena cava on the right
side.
Thoracic transverse scan. The spinal column also provides the
orientation landmark in the thoracic transverse scan. The
thoracic part of the descending aorta is located anterior to the
spinal column on the left side. In front of the aorta is the left
atrium, into which the pulmonary veins drain. The fetal heart is
located in the anterior part of the chest, with the cardiac apex
and the interventricular septal axis pointing toward the lef t
side (in the four-chamber view). The right ventricle abuts the
right anterior chest wall. It is distinguished by the presence of
the moderator band, a transverse muscle bundle located at the
right ventricular apex. The left ventricle lies anterior to the left
atrium, which is identified by its relationship to the aorta.
a
22
Morphology of the Fetal Heart
Atria and ventricles. The right atrium and right ventricle of the
fetal heart are each slightly larger than the left atrium and left
ventricle.
Foramen ovale. The foramen ovale is an opening between the
right atrium and left atrium. It occupies approximately one-
third of the interatrial septum and measures about two-thirds
the diameter of the aortic root. Consistent with the right-to-
left shunt through the foramen ovale, the free edge of the sep-
tum primum is deviated to the left.
Cardiac valves. An atrioventricular (AV) valve is located be-
tween each atrium and the corresponding ventricle, and the
normal function of these valves should be confirmed by Dopp-
ler sonography. The same applies to the semilunar valvesof the
pulmonary and aortic arteries. The aortic valveis located at the
center of the heart where the atrioventricular septum and AV
valve plane intersect (five-chamber view). In the long-axis
view, the pulmonary artery is anterior, and the ductus arterio-
sus (DA) connects the pulmonary trunk with the descending
aorta by way of the ductal arch. The aortic arch and ductal arch
can both be identified in the long-axis view and its variations.
Normally the two great arteries cross each other after leaving
the heart (crossing of the outflow tracts).
b
c
204
Fig. 22.11 a The aortic arch (with the fetal spine above). The three
brachiocephalic vessels are seen arising from the aortic arch.
b Color Doppler image of the aortic arch in the same plane demon-
strates the origins of the brachiocephalic trunk (1), left carotid artery
(2), and left subclavian artery (3). Note the associated color reversal
between the ascending aorta (AAO) and descending aorta (DAO).
c Typical Doppler spectrum of the aortic arch, indicating a low dias-
tolic flow velocity.
Color Doppler in the Diagnosis of Congenital
Heart Disease
This section reviews the echocardiographic features of specific
congenital heart defects and their associated anomalies.
The distinctive features of the heart defects and the diagnostic information that is gained by the use of color Doppler
are highlighted in boxes thus:
Distinctive features of the heart defect.
Color Doppler
Diagnostic information gained by adding color Doppler.
Defects Involving Abnormal Shunts
Atrial Septal Defect of the Ostium secundum Type
(ASD II)
Ultrasound Examination of the Fetal Heart
a
Only larger defects can be distinguished antenatally from the
foramen ovale, which normally occupies one-third of the atrial
septum (Fig. 22.
12). The following differentiating features are
helpful:
– Defect located at the center of the atrial septum
– Absence of the septum primum flap
– (Volume overload on the right atrium and ventricle)
Color Doppler
Demonstrates broad shunting of blood across the atrial septal
defect.
Total Anomalous Pulmonary Venous Return
Three main types of total anomalous pulmonary venous return
are recognized, as described below. Mixed forms may also
occur.
➤
Supracardiac anomalous pulmonary venous return. The
pulmonary veins join to form a confluence behind the left
atrium that drains through a left ascending vertical vein into
the anonymous vein and from there into the superior vena
cava.
➤
Cardiac type. The pulmonary veins drain directly into the
right atrium or into the lower part of the superior vena cava
or coronary sinus.
➤
Infracardiac type. Blood drains from the pulmonary venous
confluence into a vessel that descends through the diaphragm and opens into the ductus venosus or inferior vena
cava.
All three types have several features in common:
– The pulmonary veins do not drain into the left atrium at the
usual location.
– There is an increased volume load on the right atrium and
right ventricle, which are markedly larger than the left
atrium and left ventricle.
– An atrial septal defect is usually present.
b
RV
LV
Fig. 22.12 Large atrial septal defect in the ostium secundum position
(ASD II), 27th week of gestation.
a–c Pictured are the two atria (RA, LA) with the AV valve plane and the
entrances to both ventricles. The atrial septum is absent except for a
small portion near the AV valves. RV =right ventricle, LV =left ven-
tricle.
RA
LA
c
Color Doppler
Demonstrates the venous anomalies.
Atrial Septal Defect in the Ostium primum Position
(ASD I, Partial Atrioventricular Septal Defect)
– This defect is located in the lower part of the interatrial sep-
tum, extending to the AV valve plane (Fig. 22.
13).
Specific Obstetric Problems
205
Color Doppler Ultrasound in Fetal Echocardiography
– The defect is often combine d with AV valve regurgitation,
most commonly affecting the mitral valve.
Color Doppler
Demonstrates the shunt across the atrial septal defect and AV
valve regurgitation.
Ventricular Septal Defect (VSD)
VSD is the most common congenital heart defect, with a relative incidence of 30–35%.
➤
Defect located in the perimembranous area.
– Usually this defect is relatively easy to define with ultra-
sound (Fig. 22.
14).
Associated anomalies: tetralogy of Fallot, AV canal, transposition
of the great arteries, etc.
➤
Defect located in the muscular ventricular septum (middle
and apical septal region).
– This VSD is usually small, and so it cannot always be de-
22
tected prenatally.
Color Doppler
Color flow is not always rewarding with an isolated VSD because
the antenatal pressures in the two ventricles are approximately
equal.
Atrioventricular Septal Defect
In this anomaly, an ASD I is combined with an inlet VSD and AV
valve regurgitation (Fig. 22.
– Ultrasound demonstrates a large defect extending from the
atrium to the center of the ventricular septum and a large
“common” AV valve.
– Occasional hypoplasia of one of the ventricles.
Color Doppler
Demonstrates shunt across the atrioventricular septal defect.
15).
Fig. 22.13 Atrial septal defect in the ostium primum position (ASD I,
31st week of gestation). The lesion consists of a 3.3 mm defect in the
inferior part of the interatrial septum above the AV valve plane. RV =
right ventricle; LV= left ventricle; LA = left atrium; RA = right atrium.
The pregnant woman herself had been operated for an ASD I.
Ductus Arteriosus (DA)
– The ductus arteriosus normally connects the pulmonary
artery to the descending aorta in the fetus with right to left
shunting.
Defects involving the ductus may cause shunt reversal: Pulmonary atresia with an intact ventricular septum or VSD Tricuspid
atresia with an absence of antegrade pulmonary artery flow
Color Doppler
Color Doppler demonstrates the flow direction across the DA,
which is confirmed in the Doppler spectrum.
Constriction of the ductus arteriosus. This can result from the
maternal use of prostaglandin synthesis inhibitors (e.g., ASS
doses higher than 100 mg/kg per day or indomethacin). An increased flow velocity can be detected in the duct (systolic
velocity ⬎ 1.40m/s), and there is overload of the right heart.
206
Common in trisomy 21 and other chromosome abnormalities,
less common in heterotaxic syndromes.
LV
RV
VSD
LA
RA
ab
Fig. 22.14 Perimembranous ventricular sep-
tal defect (VSD), 30th week of gestation. Ultrasound was done to investigate fetal
arrhythmia.
a, b Four-chamber view demonstrates a
moderately large ventricular septal defect in
the perimembranous area. No additional
anomalies were found. RV = right ventricle;
LV = left ventricle; LA = left atrium; RA = right
atrium.
Ultrasound Examination of the Fetal Heart
Fig. 22.15 Complete atrioventricular sep-
tal defect, 24th week of gestation.
DAO
LV
RV
ab
a, b Four-chamber view with the AV valves
closed. The septum primum defect (ASD I)
can be identified.
c, d In a four-chamber view with the AV
valves open, the large composite defect
(ASD I plus VSD) can be seen. DAO =descending aorta’ RV = right ventricle;
LV = left ventricle.
cd
Defects with Obstruction of the Left Heart
Valvular Aortic Stenosis (Fig. 22.
The left ventricle in this condition may exhibit a variety of mor-
phological criteria.
➤
Dilated left ventricle. Poor pump function, mitral insuffi-
ciency.
➤
Normal-size left ventricle. Usually there is only moderate
16)
Coarctation of the Aorta
The degree of this malformation is variable. The most severe
form is interruption of the aortic arch. Coarctation of the aorta
is rarely diagnosed before birth. The complete form is usually
detected postnatally after the ductus arteriosus has closed.
– Diagnosis is aided by hypoplasia of the aortic arch and a nar-
row isthmus.
– The left ventricle and ascending aorta may be hypoplastic.
impairment of pump function.
➤
Small left ventricle. Narrow ventricular cavity, myocardial
hypertrophy, endocardial fibroelastosis.
– Base of aortic valve and ascending aorta are narrow or of
Color Doppler
Color flow does not add diagnostic information in the isthmic region.
normal width.
– Aortic valve is thickened.
– Left atrium is dilated (especially with mitral insuffi-
ciency).
Associated ventricular septal defect in 25 % of cases. Associated
chromosome abnormalities (45 XO, trisomy 13 or 18).
– Left-to-right shunt through the foramen ovale or intact in-
teratrial septum with severe stenoses.
Hypoplastic Left Heart Syndrome (Fig. 22.17)
– Doppler flow velocity in the ascending aorta is usually in-
creased, but may be normal or reduced if there is severe
aortic stenosis with impaired left ventricular function.
– Hypoplasia, high-grade stenosis, or atresia of the mitral
valve and/or aortic valve
– Hypoplasia of the left atrium, left ventricle, aortic valve, as-
Color Doppler
Turbulent color pattern in the ascending aorta. Color flow may
be absent, though, if there is minimal blood flow in the ascending aorta due to a critical stenosis.
Demonstration of mitral insufficiency.
cending aorta
– Hyperechoic left ventricle (endocardial fibroelastosis)
– Reverse flow in the ascending aorta from the DA due to aortic
valve atresia
– Increased flow velocity in the ductus and descending aorta
(total cardiac output)
– Left-to-right shunt through the foramen ovale or intact in-
teratrial septum (due to increased pressure in the left
atrium)
Specific Obstetric Problems
207
Color Doppler Ultrasound in Fetal Echocardiography
ab
22
c d
ef
208
Fig. 22.16 Valvular aortic stenosis (26th week of gestation).
a In the four-chamber view, the left ventricle (LV) is not enlarged but is
hypocontractile with an echogenic endocardium (endocardial fibroelastosis). The septum secundum is deflected into the right atrium
(RA) by the increased pressure in the left atrium (LA). RV = right ventricle.
b Color flow through the foramen ovale (FO) and the Doppler spectrum indicate a left-to-right shunt resulting from the increased pressure in the left atrium.
c The base of the aortic valve is narrow (1.9 mm), and the valve is
thickened and shows decreased motion. The ascending aorta (AO)
shows poststenotic dilatation (5 mm).
d The maximum systolic Doppler gradient across the aortic valve is
130 mmHg.
e Mitral insufficiency because of pressure load on the left ventricle.
The flow is encoded in blue, indicating a flow direction from the left
ventricle into the left atrium.
f Color-encoded flow from the left pulmonary vein. Doppler indicates
brief reverse flow (encoded in blue) during atrial contraction.
Ultrasound Examination of the Fetal Heart
Color Doppler
Absence of blood flow into the left ventricle.
Absence of antegrade blood flow in the ascending aorta.
Possible reverse flow in the ascending aorta (from the DA).
Left-to-right shunt across the foramen ovale.
Rarely, the syndrome is combined with VSD or transposition of
the great arteries. Relatively high familial risk of recurrence (10–
20%).
All defects involving a left ventricular outflow tract obstruction
are an indication for serial ultrasound examinations, as the defect often does not become fully developed until the second
half of the pregnancy. Approximately 7% of these heart defects
are associated with fetal hydrops.
Defects Involving Obstruction of the Right Heart
a
In all heart defects that are associated with stenosis of the pulmonary valve and/or hypoplasia of the pulmonary trunk, it is
common to find that the degree of stenosis increases mainly in
the third trimester of pregnancy. It can be difficult to differentiate complete valvular atresia from a high-grade stenosis.
Specific Obstetric Problems
Valvular Pulmonary Stenosis
– Thickened pulmonary valve
– Hypertrophy of the right ventricle (depending on the degree
of stenosis)
Color Doppler
Turbulence in the pulmonary trunk due to accelerated flow
across the pulmonary valve.
Critical Pulmonary Stenosis, Pulmonary Atresia with
b
an Intact Ventricular Septum
– No opening of the atretic pulmonary valve
– Hypertrophic right ventricle, usually with a small cavity
– Frequent hypoplastic tricuspid valve, tricuspid insufficiency
(Fig. 22.18)
컅 Fig. 22.17 Hypoplastic left heart syndrome (37th week of gestation).
a Four-chamber view: the right atrium (RA) is markedly dilated, and
the right ventricle (RV) is slightly enlarged. The cavity of the left ven-
tricle (LV) is hypoplastic with an atretic mitral valve.
b Color Doppler image confirms mitral valve atresia.
c Hypoplastic ascending aorta (AAO, diameter 3 mm) with aortic
c
valve atresia (valve diameter 1.8 mm). Antegrade flow is not demonstrated by spectral or color Doppler. PA= pulmonary artery.
209
Color Doppler Ultrasound in Fetal Echocardiography
Fig. 22.18 Pulmonary atresia with an intact ventricular septum.
a Four-chamber view: the right atrium (RA) is markedly enlarged, and
the tricuspid valve and right ventricle (∗) are hypoplastic. LA = left
atrium; LV = left ventricle.
Color Doppler
Reverse flow in the pulmonary trunk via the DA with pulmonary
22
atresia.
Tetralogy of Fallot (Fig.22.19 )
– Both ventricles are of equal size.
Color Doppler
Ventricular septal defect with a broad aorta overriding the
ventricular septum defect; the degree of pulmonary stenosis and
hypoplasia of the pulmonary trunc are often increasing during
the third trimester.
Turbulence in the pulmonary trunk.
b Color flow shows pronounced tricuspid insufficiency with a jet
directed onto the lateral wall of the right atrium (with kind permission
of Professor Michael Hofbeck, Department of Pediatric Cardiology,Tü-
bingen University Children’s Hospital).
Association with chromosome abnormalities:
CATCH 22 (acronym for cardiac defects, abnormal facies, thymic
hypoplasia, cleft palate, hypocalcemia, and chromosome 22).
Associated with DiGeorge syndrome, velocardiofacial syndrome, and conotruncal facial anomaly syndrome.
Coexists with atrioventricular septal canal defect in trisomy 21.
Pulmonary Atresia with Ventricular Septal Defect
– Like the tetralogy of Fallot, but with an atretic pulmonary
valve
– Variable hypoplasia of the pulmonary trunk
Color Doppler
Reverse flow in the pulmonary trunk through the DA.
a b
b Aortic flow demonstrated by color and spectral Doppler. The aortic
flow velocity is 120 cm/s.
210
Fig. 22.19 Tetralogy of Fallot (35th week of gestation).
a Four-chamber view with a subaortic ventricular septal defect. There
is apparent marked dextroposition of the aorta. RV = right ventricle;
LV = left ventricle; AAO= ascending aorta.
a
b
c
Fig. 22.20 Tricuspid atresia with a ventricular septal defect (32nd
week of gestation).
a The four-chamber view shows a large left ventricle (LV) that communicates with a hypoplastic, anteriorly situated right ventricle (RV)
through a 2.6 mm ventricular septal defect (VSD). The tricuspid valve
is atretic. LA = left atrium; RA = right atrium.
b Color Doppler image demonstrates flow from the left ventricle into
the right ventricle across the ventricular septal defect (encoded red)
and flow from the right atrium into the left atrium across the atrial sep-
tal defect (encoded blue).
c Doppler spectrum of flow in the inferior vena cava shows a brief period of reverse flow during atrial contraction (indicating right-sided in-
flow stasis).
Ultrasound Examination of the Fetal Heart
Tricuspid Atresia (Fig. 22.20)
– Variable hypoplasia of the right ventricle, hypertrophy of the
ventricular myocardium, small right ventricular cavity
– Enlarged right atrium
– Frequent ventricular septal defect of variable size, with a
tendency to occlude
Color Doppler
With a ventricular septal defect: antegrade flow in the pulmo-
nary trunk.
With pulmonary atresia: reverse flow across the DA.
Absence of inflow through the tricuspid valve into the right ventricle.
Rarely, combined with transposition of the great arteries. These
cases have a hypoplastic ascending aorta.
Single Ventricle
Single ventricle (univentricular heart) is the term for a very
heterogeneous group of anomalies whose varying pathomorphological features determine the therapeutic approach and
the prognosis. In all forms, only one functionally competent
ventricle is present; the second ventricle is usually present but
hypoplastic. The classification of this anomaly is based on the
configuration of the AV valves and ventricles and on the ventriculoatrial connection (Fig.22.
➤
Atrioventricular connection
– Two AV valves open into the main chamber (double-inlet
configuration)
– One common AV valve
– One absent or atretic AV valve
➤
Ventricular morphology
– Morphological right ventricle with a left ventricular outlet
chamber
– Morphological left ventricle with a right ventricular outlet
chamber
– Common ventricle with a right and left ventricular com-
ponent; the ventricular septum is (almost completely) ab-
sent
– Single ventricle of indeterminate morphology
➤
Ventriculoatrial connection
– Normal position of the great arteries
– Transposition of the great arteries
– Frequent hypoplasia, stenosis, or atresia of one of the two
arteries
The principal associated cardiac anomalies, besides atrial septal
defect, are systemic venous anomalies (heterotaxy syndrome)
and abnormalities of cardiac position and of thoracic and
abdominal situs.
The most common variants of this complex anomaly are tricuspid atresia, mitral atresia or hypoplastic left heart syndrome, double-inlet left ventricle, and double-outlet right ventricle. Complete absence of the second ventricle is rare. Factors
that critically affect peri- and postnatal hemodynamics and the
therapeutic approach are the interatrial communication, persistence of the ductus arteriosus, and possible obstruction of
the right or left ventricular outflow tract or the associated arterial vessel.
21).
Specific Obstetric Problems
211