Diagnostic ultrasound ( PDFDrive )

1288 PART IV Obstetric and Fetal Sonography
RV
LV
IVS
AO
weeks’ gestation using transvaginal ultrasound. 33 Color Doppler
imaging is helpful in making the diagnosis of TOF. 135
he newborn with the classic form of TOF who has pulmonary
stenosis rather than pulmonary atresia is typically asymptomatic
at birth but develops cyanosis and a murmur in the irst weeks
of life. Early primary repair of TOF is routinely performed with
a low surgical mortality and postoperative morbidity. 136 Typical
cases of TOF are repaired at 4 to 6 months of age, with close to
90% survival at 1 year. 137 Patients surviving early surgery (before
5 years old) have a 32-year survival of 90%. 138 he presence of
congestive heart failure in the fetus or newborn with TOF is
associated with 17% to 41% mortality. 139,140
FIG. 37.31 Tetralogy of Fallot. The aorta (AO) overrides both the
right ventricle (RV) and the left ventricle (LV). A ventricular septal defect
(arrows) is also appreciated. See also Video 37.13. IVS, Interventricular
septum.
a single ventricle with absence of the interventricular septum is
seen. Doppler ultrasound examination is helpful in determining
if a normal outlow tract is present. A nonfunctioning, rudimentary
accessory ventricle may be present in some cases.
Diferential diagnosis includes a large VSD and hypoplastic right
or let ventricle.
Patients with outlow tract stenosis have a poor prognosis. 127
Death is typically caused by congestive heart failure or arrhythmia.
77 Pulmonary artery banding and shunts yield a 70% 5-year
survival rate. Ventricular septation has a postoperative survival
rate of approximately 56%. 125,128 More recent literature indicates
that there continues to be a high mortality rate for univentricular
heart ater surgical correction, with an 8-year survival ater
modiied Blalock-Taussig shunt of only 68%. 129 Ater a Glenn
bidirectional cavopulmonary connection, 8-year survival is
slightly higher at 74%. 130
Tetralogy of Fallot
Tetralogy of Fallot consists of (1) VSD, (2) overriding aorta,
(3) hypertrophy of the right ventricle, and (4) stenosis of the
right ventricular outlow tract (Fig. 37.31, Video 37.13). It accounts
for 5% to 10% of CHD in live births 46 and is associated with a
variety of cardiac, extracardiac, and chromosomal anomalies. 72
A study of 129 fetuses diagnosed in utero with TOF reported
additional cardiac anomalies in 57%, extracardiac anomalies in
50%, and chromosomal anomalies in 49%. he irst trimester
nuchal translucency was above the 95th percentile in 47% of
fetuses. 131
TOF occurs when the conus septum is located too far
anteriorly, thus dividing the conus into a smaller, anterior right
ventricular portion and a larger posterior part. Closure of the
interventricular septum is incomplete, causing the aorta to
override both ventricles. 132 he VSD typically occurs in the
perimembranous portion of the septum. Right ventricular
hypertrophy rarely occurs in utero, but the overriding aorta is
reliably seen. 133,134 Pulmonary atresia or stenosis, or a dilated
pulmonary artery secondary to absence of the valve, may be
appreciated. he diagnosis of TOF has been made before 15
Truncus Arteriosus
Truncus arteriosus accounts for 1.3% of fetal cardiac anomalies
and is characterized by a single large vessel arising from the base
of the heart. his vessel supplies the coronary arteries and the
pulmonary and systemic circulations. Aortic anomalies occur
in 20% and noncardiac anomalies in 48% of patients with truncus
arteriosus. 141 In almost all patients a VSD is present. he truncal
valve may have two to six cusps and in general overrides the
ventricular septum. Four types of truncus arteriosus have been
identiied by Collett and Edwards, 142 as follows:
• Type I has a pulmonary artery that bifurcates into right and
let branches ater it arises from the ascending portion of the
truncal vessel.
• Type II has right and let pulmonary arteries arising separately
from the posterior truncus.
• Type III has pulmonary arteries that arise from the sides of
the proximal truncus.
• Type IV has systemic collateral vessels from the descending
aorta as the source of low.
he single, large truncal artery with overriding ventricular
septum and an associated VSD is identiied on four-chamber and
outlow tract views (Fig. 37.32). his anomaly has been diagnosed
as early as 13 weeks. 34 Color Doppler imaging is particularly
helpful in the setting of truncus arteriosus because it facilitates
accurate localization of the pulmonary arteries and rapidly detects
truncal valvular insuiciency. In the 1980s, prognosis was poor,
with an overall mortality of 70%. 141 More recent studies have
indicated that 10-year to 20-year survival is excellent for infants
undergoing complete repair of truncus arteriosus. 143 However,
these patients continue to experience signiicant comorbidities
throughout childhood, with signiicant deicits in exercise tolerance
and overall functional status. 144
Double-Outlet Right Ventricle
Double-outlet right ventricle (DORV) represents less than 1%
of all CHD and occurs when more than 50% of both the aorta
and the pulmonary artery arise from the right ventricle. 145,146
DORV is classiied into the following three types:
• Aorta posterior and to the right of the pulmonary artery
• Aorta and pulmonary artery parallel, with the aorta to the
right (Taussig-Bing type)
• Aorta and pulmonary artery parallel, with the aorta anterior
and to the let