Structural cardiac anomalies

Despite the increasing use of prenatal ultrasonography, it is estimated that only 15% of major congenital heart defects are detected before birth.(10) With a prevalence of 8 per 1000 live births, an effort to improve the prenatal diagnosis of congenital heart disease is warranted.(17) The four-chamber view of the fetal heart can identify 40% to 50% of congenital heart disease and the addition of views of the ventricular outflow tracts can increase detection to 60% to 80% (Fig. 1).(35) Universal screening for cardiac malformations at the time of routine prenatal ultrasound provides the best opportunity to identify structural heart defects because up to 90% occur in low risk patients. In fact, an abnormal cardiac screen has become the most common reason for referral for fetal echocardiography and is more predictive for congenital heart disease than all other risk factors combined.(5, 10) The most common cardiac defects observed in live-born infants tend to be the most difficult to diagnose prenatally. These include ventricular septal defects, patent ductus arteriosus, atrial septal defects, stenosis of the semilunar valves, and coarctation of the aorta.(17) Fortunately, many of these defects are not immediately life threatening and the long-term prognoses are favorable. In contrast, many serious structural cardiac anomalies can be identified at the time of routine prenatal ultrasound in the midtrimester. Although these patients benefit from consultation with pediatric cardiology, genetics, pediatric cardiac surgery, and neonatology, some basic information about frequency, prenatal diagnosis, associated findings, and prognosis is useful for initial counseling when such major heart defects are found.