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a Chapter 33 Doppler Echocardiography for Managing Congenital Cardiac Disease 495
Fig. 33.13 A,B. Duplex pulsed Doppler
echocardiographic demonstration of mitral
and tricuspid regurgitation in a fetus
with cardiomyopathy. A Top: Apical fourchamber
view of the fetal heart with
the Doppler sample volume placed at
the mitral orifice. A Bottom: Mitral waveforms
with flow from the left atrium to
the left ventricle as upward defections
and the regurgitant flow as downward
defections (arrows). B Top: Apical fourchamber
view of the fetal heart with
the Doppler sample volume placed at
the tricuspid orifice. B Bottom.: Tricuspid
Doppler waveforms. Right atrium to ventricle
flow is shown as upward deflections
and the ventriculoatrial regurgitant flow
as downward deflections
complex and occasionally isolated cardiac structural
malformations or cardiomyopathy (Table 33.8). Figure
33.13 shows mitral and tricuspid regurgitation in
a fetus with cardiomyopathy.
Ebstein's Anomaly
An uncommon malformation, Ebstein's anomaly is
identifiable in the fetus with relative ease by 2D and
Doppler echocardiographic scans. The defining malformation
is apical displacement of the tricuspid
valve leaflets from the annulus, affecting the septal
and posterior leaflets and occasionally the anterosuperior
leaflet. In addition to the displacement, the
valves are dysplastic and have varying degrees of distal
attachment [41]. As a result of valvular displacement,
the superior or proximal part of the right ventricular
chamber is incorporated into the functional
right atrial chamber. This situation is known as atrialization
of the right ventricle. The inferior or distal
part of the ventricular chamber retains the pumping
role. The tricuspid valves also demonstrate incompetence
of varying severity, and the resulting regurgitant
flow contributes to the right atrial dilation. These
features are recognizable by 2D imaging and can be
corroborated by Doppler insonation. The latter is essential
for detecting and assessing the severity of
valvular incompetence (Fig. 33.14). There are associated
anomalies of the heart, the prenatal diagnosis
of which may be facilitated by use of Doppler sonog-