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a Chapter 35 Doppler Echocardiographic Assessment of Fetal Cardiac Failure 525
Table 35.3. Changes in Doppler flow velocities with cardiac
anomalies. I increased, D decreased, A absent, U unchanged,
R possible regurgitation, V variable. (From [45])
Anomaly
Velocity flow
Tricuspid
valve
Mitral
valve
Pulmonary
artery
Aorta
Hypoplastic D I D I
right heart
Hypoplastic I A I A
left heart
Tricuspid atresia
A I D
Ebstein's IorR I D I
anomaly
Pulmonary IorR I A I
atresia
Tetralogy of U U D I
Fallot
Transposition U U U U
Double-outlet I D V V
right ventricle
Atrioventricular
canal
IorR IorR VV
can (a) confirm the presence or absence of normal
flow patterns in cardiac structures, (b) note the presence
of abnormal flow patterns such as valvular regurgitation,
absence of normal chamber filling (which
might be seen in valvular atresia), or increased peak
velocity (which may be seen in cases of valvular stenosis),
and (c) identify reversal of normal flow direction
(such as in the foramen ovale and aortic arch in
the case of mitral atresia or in the ductus arteriosus
with pulmonary atresia). In cases of fetal ventricular
septal defect (VSD), however, there is little flow
across the VSD since the pressure gradient between
the two ventricles is minimal during intrauterine life.
Table 35.3, modified from an article by Reed, shows
the alterations in velocity flow that are frequently
seen in many cases of congenital heart disease [45].
Umbilical and middle cerebral artery flow in fetuses
with congenital heart disease was evaluated by Meise
et al., who found little change in arterial blood flow
velocities compared with normal fetuses [46]. Only in
fetuses with severe outflow tract obstructions were
there significant changes in arterial flow. They felt
that abnormal arterial Doppler waveforms reflected
uteroplacental dysfunction rather than alterations
caused by the congenital heart disease.
A number of authors have reported hydrops fetalis
and fetal heart failure associated with congenital
heart disease. Sahn et al. reported a case of trisomy
13 with hypoplastic left heart syndrome that developed
hydrops fetalis [44]. Interrogation of the tricuspid
valve revealed high-velocity flow, 1.5 times greater
than the normal values for their laboratory. Blake
et al. reviewed a series of twenty fetuses with hypoplastic
left heart syndrome [33]. Three of the 11
(27%) fetuses that were not terminated died in utero,
most likely secondary to fetal cardiac failure. These
authors also point out the importance of antenatal diagnosis
of congenital heart disease. It allows (a)
timely cytogenetic studies to be done, (b) early diagnosis
and intervention in the neonatal period and
planning for definitive therapy, and (c) additional
time for parents to plan and discuss various treatment
options for the fetus and obtain sufficiently informed
consent.
Additional reports of fetal heart failure in infants
with congenital heart disease have also been published
in the literature. Respondek et al. reported a
case of heart failure in a fetus with left atrial isomerism
(common atrium) associated with complete heart
block [47]. Color Doppler flow showed abnormal, turbulent
flow in the regions of both the pulmonary artery
and the aortic valve and increased flow velocity
across the atrioventricular valves. Pericardial effusion
and hepatomegaly were also noted. The infant died
shortly after birth and an autopsy also disclosed unsuspected
vegetation close to the thickened atrioventricular
valves. The endocardium also showed evidence
of endocarditis. Guntheroth et al. [48] and De-
Vore et al. [49] have reported abnormal flow studies
in cases of pulmonary valve stenosis or atresia. Tricuspid
regurgitation was felt to be a key sign of impending
fetal heart failure. Rustico et al. reported a
case of endocardial fibroelastosis associated with critical
aortic stenosis and abnormal outflow track flow
diagnosed at 15 weeks' gestation.
An excellent review of the use of color Doppler
flow studies for the diagnosis of congenital heart disease
can be found in two articles by DeVore et al.
[49] and DeVore [51]. They describe abnormal Doppler
flow findings in some of the more common cardiac
anomalies:
1. Aortic stenosis: retrograde flow into the left atrium
during ventricular systole.
2. Ventricular septal defect (VSD): since the pressure
in the left and right ventricle are almost identical
in the fetus, there is frequently no flow disturbance
across the septum. Flow disturbances may be seen,
however, when there is an associated abnormality
of the outflow tract with increased resistance to
the flow of blood leaving the ventricle.
3. Atrioventricular canal defect (AV canal): the presence
of AV valvular regurgitation has been found
to be a sign of developing hydrops fetalis and
heart failure.
4. Atrial septal defect (ASD): reverse flow (left±right
shunt) across the ASD may lead to right ventricular
dilatation and heart failure.