Diagnostic ultrasound ( PDFDrive )

CHAPTER
37
The Fetal Heart
Elizabeth R. Stamm and Julia A. Drose
SUMMARY OF KEY POINTS
• Moderate to severe congenital heart disease (CHD) occurs
in approximately 6 per 1000 live births.
• The incidence of CHD is much higher in the fetal
population, estimated to be at least 15 per 1000.
• The incidence of CHD is higher with positive family
history, monochorionic twins, and in vitro
fertilization.
• Most fetuses with CHD have no known risk factors.
• Fetal echocardiography is a safe and effective method of
detecting CHD.
• Early detection of CHD may have a substantial impact on
care and prognosis, allowing intrauterine therapy, carefully
planned delivery, and parental counseling.
• Advancements in surgical techniques and perioperative
management have signiicantly improved prognosis in
many cases.
CHAPTER OUTLINE
NORMAL FETAL CARDIAC
ANATOMY AND SCANNING
TECHNIQUES
STRUCTURAL ANOMALIES
Atrial Septal Defect
Ventricular Septal Defect
Atrioventricular Septal Defect
Ebstein Anomaly
Hypoplastic Right Ventricle
Hypoplastic Left Heart Syndrome
Univentricular Heart
Tetralogy of Fallot
Truncus Arteriosus
Double-Outlet Right Ventricle
Transposition of Great Arteries
Anomalous Pulmonary Venous Return
Coarctation of Aorta
Aortic Stenosis
Pulmonic Stenosis
Cardiosplenic Syndromes
Cardiac Tumors
Cardiomyopathy
Ectopia Cordis
ARRHYTHMIAS
Premature Atrial and Ventricular
Contractions
Tachycardia
Bradycardia
Congenital Heart Block
Sonographic evaluation of the fetal heart can identify cardiac
abnormalities that afect obstetric care in a variety of ways,
including mode of delivery, location of delivery, intrauterine
therapy, parental reassurance, and opportunity for termination.
Congenital heart disease (CHD) is a signiicant problem, with
an incidence of moderate and severe CHD of approximately 6
per 1000 live births. If trivial lesions such as tiny muscular
ventricular septal defects (VSDs) are included, the incidence
is as high as 75 per 1000 live births. 1 It is more diicult to
determine the exact incidence of CHD in the fetal population.
One large study suggested that CHD occurs in at least 15 per
1000 fetuses. 2 More than 20% of perinatal deaths caused by
congenital malformations are the result of a congenital heart
defect. 3 In 85% of CHD cases, both environmental and genetic
factors are involved (Table 37.1). 4-7 he remaining 15% of cardiac
anomalies are associated with a single gene or chromosomal
abnormality. 5 he risk of CHD increases to 2% to 3% with an
afected sibling and to approximately 10% with two afected
siblings or an afected mother—although the incidence is variable
depending on the type of CHD in the afected relative. 5,8 he
risk to ofspring of afected mothers is substantially higher than
for those with afected fathers, suggesting that cytoplasmic
inheritance may play a role in the genetics of CHD (Tables 37.2
and 37.3). Only 50% of recurrent heart lesions are of the same
type as the previously diagnosed defect. 9
Extracardiac malformations occur in 25%, 10 and chromosomal
anomalies occur in 13% of live-born neonates with
CHD. 11-13 About 50% of fetuses with nonimmune hydrops and
cardiac anomalies have a chromosomal anomaly, and 10% will
have extracardiac anomalies. 14 Hydrops in the setting of CHD
is predictive of a very poor prognosis.
Although the most common indications for formal fetal
echocardiography are family history of CHD and fetal arrhythmia,
the majority of these fetuses will have normal hearts. he
highest incidence of CHD occurs in patients referred because
of an abnormal four-chamber view, fetal hydrops, or signiicant
polyhydramnios on a routine obstetric ultrasound. 15,16 A routine
ultrasound examination with a suspected fetal cardiac anomaly
is associated with a 50% to 69% risk of CHD in live-born
infants. 17,18 Monochorionic twins are at a higher risk for CHD,
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