o_1977r8vv9vk1ts2ms0kd8pksa.pdf

468 D. Maulik
Table 32.2. Echocardiographic planes
Apical four chamber
Basal four chamber
Lateral four chamber
Ventricular long axis
Aortic outflow
Pulmonic outflow
Ventricular short axis
Ventricular apex
Ventricular chamber
Mitral-tricuspid plane
Ventricular base
Aortic arch
Pulmonic-ductal arch
Fig. 32.4. Method for obtaining an apical four-chamber
view of the fetal heart. Far left: Orientation of the transducer
plane in relation to the fetal thorax. Bottom left: Echocardiographic
plane in relation to the fetal heart
Table 32.3. Information content of fetal echocardiographic
examination
Location of the heart in the thorax
Cardiac size: normally one-third of the thoracic
cross-sectional area
Number of cardiac chambers
Comparability of right and left atrial sizes
Comparability of right and left ventricular sizes
Aortic and pulmonary outflow tracts and their crossover
relation
Integrity of the atrial and ventricular septa
Location and movement of the tricuspid and mitral
valves
Location and movement of the valve of the foramen
ovale in the left atrium
Abnormal flow patterns
Abnormal rhythm
Presence of effusion, pericardial and pleural
and reliability of the procedure for general application.
The views of the fetal heart at various echocardiographic
planes are described below. These views
offer a comprehensive evaluation of the fetal heart,
although they do not constitute all the available
approaches to cardiac imaging. The minimal information
to be derived from the 2D fetal echocardiographic
examination is listed in Table 32.3.
Four-Chamber View
As the fetal heart lies horizontally in the thorax, a
cross-sectional scan of the fetal thorax just above the
level of the diaphragm reveals the four-chamber view
of the fetal heart (Fig. 32.4). It is an apical four-chamber
view when the fetal spine is posterior, as encountered
in the occipitoposterior position (Fig. 32.5 A).
When the fetus is in the occipitoanterior position with
the fetal spine directed anteriorly, the cardiac apex is
directed toward the maternal spine and the base faces
the maternal anterior (Fig. 32.5 B). This position constitutes
the basal four-chamber view. When the fetus
lies on its side in the occipitolateral position, the lateral
four-chamber view is visualized with the cardiac apex
directed laterally (Fig. 32.5C).
The four-chamber view is one of the most important
approaches for fetal cardiac assessment. It is
readily obtainable, does not require in-depth expertise
in the echocardiographic technique, and yields
an immense body of information regarding the functional
integrity of the fetal heart. Although it constitutes
an essential component of the screening examination
of the fetus, it should be clearly recognized
that this view in itself is not sufficient for ruling out
fetal cardiac malformations and cannot act as a surrogate
for comprehensive systematic sonographic examination
of the fetal heart.
The four-chamber view allows assessment of the following
components of the fetal cardiac anatomy: atria,
interatrial septum, foramen ovale and its valve, eustachean
valve, tricuspid and mitral valves, ventricles,
and interventricular septum. The right and left ventricles
appear to be of comparable size. The right ventricle
is nearer the anterior abdominal wall, whereas the
left ventricle faces the posterolateral abdominal wall
and is nearer the spine. The septomarginal trabeculum,
or moderator band, can be seen near the apex in contiguity
with the interventricular septum. The right ventricular
cavity is irregular, whereas the left cavity is
smooth. The tricuspid and mitral orifices and the respective
valves are clearly imaged in this plane. The
former is situated more toward the apex than the latter.
The right and left atria appear to be of similar size. The
superior and inferior vena caval entry into the right atrium
and the pulmonary venous entry into the left atrium
may also be seen in this or a similar plane. The
interatrial septum can be visualized separating the at-