o_1977r8vv9vk1ts2ms0kd8pksa.pdf

456 R. Chaoui et al.
supported by a recent observation we reported in two
different cases of hypoplastic left heart [15], one
showing a wide patent and the other a sealed foramen
ovale. In the patent interatrial communication, the
pulmonary venous velocity waveform was normal
with a positive A-wave. In the sealed foramen ovale,
however, the waveform showed a nearly to-and-fro
pattern (Fig. 31.12), since all blood flow coming from
the lung returns back into the lung. This is associated
with congested pulmonary veins. This chronic high
pressure leads to vascular damage as observed at autopsy,
with arterialization of pulmonary veins as well
as the development of lymphangiectasia of the lung
as we observed in other cases.
In a further study we examined changes of the
velocity waveforms in other heart anomalies (n=96)
and were not able to find any changes depending on
the heart anomaly, mainly due to the interatrial conditions
of obstruction [16].
Besides obstructed left atrium conditions (e.g., hypoplastic
left heart, mitral atresia), we also found abnormal
waveform patterns in TAPVC. In this severe
malformation pulmonary veins are not connected to
the left atrium and interestingly velocity waveforms
reflect the site of connection. When connecting to a
descending channel into the liver, infradiaphragmatic
blood flow in the pulmonary veins was shown to be
continuous [3]. Connection directly to the right atrium
or indirectly via a vertical vein may show pulsations
but not with the typical shape of a pulmonary
vein [12]; therefore, it has been suggested that the
routine use of pulsed Doppler of lung veins may help
in diagnosing TAPVC in the fetus.
In summary, it can be emphasized that left atrial
obstruction as seen in hypoplastic left heart syndrome
or mitral atresia can be associated in most
cases with an increased pulsatile flow due to the reversal
of flow during atrial contraction. A to-and-fro
pattern is suggestive for a sealed foramen ovale and
associated with severe impairment of lung development,
showing a poor prognosis. Flow pulsations are
decreased or absent in TAPVC with infradiaphragmatic
connection, or show an atypical pattern resembling
inferior vena cava or a more dumped pattern in
cardiac or supracardiac connections.
Other Fields of Interest Assessing
Pulmonary Vein Doppler
The relationship of pulmonary venous flow with systolic
and diastolic cardiac times assessed at the level
of the mitral valve are used in cardiology to assess
diastolic function. Brezinka and coworkers [17] analyzed
this relationship in 28 healthy fetuses in the
second half of pregnancy and found that pulmonary
venous inflow into the left atrium occurs predominantly
during the filling and ejection phases of the
cardiac cycle. Absolute cardiac diastolic and systolic
time intervals as well as the distribution of pulmonary
venous flow velocity integrals between these cardiac
time intervals remained unchanged with advancing
gestational age.
Macklon and coworkers [18] examined the influence
of fetal behavioral states on venous blood flow
velocity waveforms in ten normally grown fetuses at
term. The examinations were performed either during
quiet (state 1F) or active (state 2F) sleep. Whereas no
changes were observed on the arterial side, venous
pulmonary blood flow velocity waveforms demonstrated
a significant increase in time-averaged peak
diastolic and end-diastolic velocity during active
sleep, suggesting an increase of pressure gradient
between the pulmonary venous system and the left
atrium in these behavioral states.
DeVore and Horenstein [19] described a new technique
for the evaluation of fetal arrhythmia by simultaneous
recording of the intraparenchymal pulmonary
artery and vein. Since both vessels are adjacent
to each other within the lung showing opposite flow
directions, a simultaneous spectral Doppler sampling
will demonstrate waveforms on both sides of the
baseline (Fig. 31.13): the peak of the pulmonary artery
reflects the ventricular systole, whereas the atrial
Fig. 31.13. Simultaneous pulmonary artery and vein Doppler
tracing in a normal fetus. Sampling is performed in
lung parenchyma where peripheral pulmonary artery and
veins are adjacent to each other. Peak velocity on the arterial
side indicates systole (S) and is observed on the venous
side as well. The nadir on the venous side indicates the
atrial contraction (A)