Diagnostic ultrasound ( PDFDrive )

1292 PART IV Obstetric and Fetal Sonography
A
B
FIG. 37.38 Coarctation of Aorta. (A) Gray-scale image showing narrowing of the aortic arch (arrow) at the level of the isthmus. (B) Spectral
Doppler tracing shows increased velocity and bidirectional blood low through the aortic arch.
Aortic Stenosis
Aortic stenosis is a stricture or obstruction of the ventricular
outlow tract occurring in 5.2% of newborns. 46 Aortic stenosis
is divided into supravalvular, valvular, and subvalvular types.
he supravalvular type of aortic stenosis has not been reported
in utero. Valvular aortic stenosis is more frequent in males and
is associated with a bicuspid aortic valve and chromosomal
abnormalities. 171 Subvalvular aortic stenosis is associated with
inherited disorders, asymmetrical septal hypertrophy (ASH),
and hypertrophic obstructive cardiomyopathy. Infants of diabetic
mothers may have a transient form of let ventricular outlow
tract obstruction secondary to ASH.
hickening of the aortic valve, poststenotic dilation of the
aorta, and ventricular enlargement are clues to valvular aortic
stenosis. In addition, real-time evaluation of the aortic valve
may show it persisting, as opposed to moving normally in and
out of the ield of view. hickening of the interventricular septum
may be seen in subvalvular aortic stenosis. In all cases, increased
velocity through the aortic valve will be identiied on pulsed
Doppler ultrasound. Early-onset aortic stenosis results in endocardial
ibroelastosis (EF) and hypoplastic let ventricle. 172
Aortic stenosis progresses in utero and may not be apparent
on early (<16 weeks) fetal echocardiograms. In some cases these
defects may not be apparent until ater birth. 29 A mortality rate
of 23% in the irst year of life is reported with aortic stenosis. 173
Prognosis has improved with appropriate surgery, with mortality
of 1.9% to 9%. 174,175 In some cases, severe aortic stenosis in
midgestation may progress in utero to hypoplastic let heart
syndrome. In cases of critical aortic valvular stenosis, in utero
balloon valvuloplasty has been performed with good results. 176
Pulmonic Stenosis
Pulmonic stenosis may occur at the valve level or at the infundibulum.
It occurs in 7.4% of live-born infants with CHD. 46
Dysplastic and stenotic pulmonic valves are seen in Noonan
syndrome and with maternal rubella. Pulmonic stenosis is
associated with TAPVR, ASD, supravalvular aortic stenosis,
and TOF. he incidence of pulmonic stenosis is higher in
monochorionic pregnancies and is 10 times more frequent in
the recipient twin of a pregnancy afected with twin-twin transfusion
syndrome. 177 In this setting the recipient’s heart becomes
hypertrophic secondary to increased preload. his is similar to
the ASH present in fetuses of diabetic mothers and results in
anatomic obstruction of the outlow tract. 172
Increased velocity through the pulmonic valve and hypertrophy
of the right ventricle suggest pulmonic stenosis. Similar to aortic
stenosis, a real-time image of the stenotic pulmonic valve will
show it persisting in the ield of view. As with aortic stenosis,
pulmonic stenosis tends to progress in utero. Pulmonic stenosis
has a variable outcome and can be managed with closed transventricular
valvotomy or percutaneous balloon valvuloplasty. 178,179
In utero pulmonary balloon valvuloplasty has also been successful
but is still in its early phase. 180
Cardiosplenic Syndromes
Cardiosplenic syndromes are syndromes associated with asplenia
(right isomerism) and polysplenia (let isomerism). Both are
defects of lateralization in which symmetrical development of
normally asymmetrical organs or organ systems occurs. 180 Asplenia
(Ivemark syndrome) and polysplenia syndromes are usually
considered separate clinical entities. However, they have many
characteristics in common, including situs inversus or situs
ambiguus of various visceral organs, complex congenital heart
defects, 181 and increased incidence of chronic arrhythmias. 182
Pathologically, in asplenia or bilateral right-sidedness, let-sided
organs are a mirror image of normally right-sided organs. his
results in right atrial isomerism, bilateral trilobed lungs, bilateral
right bronchi and pulmonary arteries, ipsilateral location of the
aorta and IVC (either let or right side), absence of the spleen,
a midline horizontal liver, and bilateral SVC. 183 In polysplenia
or bilateral let-sidedness, the right lung and bronchial tree
morphologically mirror those of the let. In many cases, intrahepatic
interruption of the IVC with azygous continuation is
present, as are multiple spleens and let atrial isomerism. 184
Cardiac anomalies associated with these syndromes include
TAPVR or PAPVR, ASD, VSD, univentricular heart, TGA, DORV,
and pulmonic/aortic stenosis or atresia. Coarctation, hypoplastic