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The origins of fetal cardiology were in the novel and still relevant fetal lamb investigations of Rudolph and Heymann. From these early studies, we began to understand normal fetal cardiovascular physiology and developed hypotheses regarding the evolution of congenital heart disease (CHD) in utero and its influence on fetal circulation. With advances in ultrasound technology in the late 1970s and 1980s, it became possible to demonstrate normal fetal cardiac anatomy and document growth of the cardiac chambers and great arteries. Doppler investigations in the 1980s and 1990s added insight into developmental changes in normal human fetal circulation and cardiovascular function. Initial reports describing prenatal detection of fetal CHD documented a more severe spectrum of disease than that encountered after birth. This was at least in part a consequence of the ease with which the more severe pathology, including fetal hydrops, was recognized at routine ultrasound assessment.
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Advances in ultrasound technology over the past 30 years have led to monumental improvements in our ability to define fetal cardiovascular anatomy and to evaluate normal and altered myocardial function in greater detail. To date, most forms of CHD can be detected prenatally. It has even become possible to define fetal cardiovascular anatomy, function, and rhythm in detail. Fetal cardiac imaging can be performed as early as 10 to 14 weeks of gestation, only a short time after completion of cardiac morphogenesis. With rapid advances in technology, fetal cardiology has evolved as its own subspecialty that merges maternal-fetal medicine and pediatric cardiology. This chapter reviews unique aspects of this field and its role in the management of neonates with significant structural and functional CHD.
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FETAL ECHOCARDIOGRAPHY
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Pregnancies at increased risk for fetal CHD, whether structural, functional, or rhythm related, are evaluated by the fetal echocardiogram. Indications for fetal echocardiography include maternal indications (eg, maternal diabetes, autoimmune disease, infection, or exposure to teratogens), fetal indications (eg, suspected cardiac abnormality at routine ultrasound; suspected extracardiac abnormality including a chromosomal abnormality known to be associated with CHD; and conditions associated with altered fetal heart function such as twin-twin transfusion syndrome, acardiac twins, and anemia), and family history (eg, CHD in mother, father, or sibling). Although many pregnancies are referred as a consequence of maternal disease or a family history of CHD, the majority of positive referrals (pregnancies with fetal CHD) come from the low-risk patients who are referred because of a suspicion of CHD during routine ultrasound assessment. Recognition of this has prompted educational initiatives to train obstetrical ultrasound personnel for better screening of the heart at the time of routine obstetrical scanning.
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Pregnancies at risk for fetal CHD as a consequence of a known family history and maternal disease are often referred electively for fetal echocardiography at 17 to 23 weeks of gestation, prior to the gestational age limit for elective pregnancy termination in most North American practices. Many pregnancies with fetal CHD ...