Prenatal Diagnosis of Aortopulmonary Window by Fetal Echocardiography
A 35-year-old G2P1 was referred for fetal echocardiography at 32 weeks’ gestation. The indication was an abnormal vessel at the level of the atria on a routine ultrasound examination. Fetal echocardiography demonstrated situs solitus with levocardia and normal atrioventricular and ventriculoarterial connections. Apart from a prominent Eustachian valve, no abnormality was detected at the level of the atria. On initial inspection, the outflow tracts appeared dilated with an aortic root diameter of 8 mm. Further evaluation of the outflow tracts demonstrated a large aortopulmonary window measuring 6×9 mm with a right-to-left shunt. No additional cardiac malformation was evident, and both the aortic arch and the pulmonary outflow tract appeared to be normal.
In a longitudinal view of the outflow tracts, the aortic and pulmonary roots had the appearance of a “spring onion” with dilatation at the proximal aspect with distal tapering (Figure 1). In a short-axis view of the aorta and pulmonary artery, the window was imaged clearly in its short-axis dimension (Figure 2). The fetus subsequently was delivered at term and the findings confirmed by a postnatal echocardiogram (Figures 1 and 2⇓). The only additional finding not apparent on the prenatal ultrasound was a right aortic arch.
Early recognition of an aortopulmonary window is important, because if not corrected, the patient tends to develop severe pulmonary vascular disease. The demonstration of a missing aortopulmonary septum is essential for definitive diagnosis. Therefore, even if dilatation of the cardiac outlets is a clue for the fetal ultrasonographer, the aortopulmonary septum should be visualized in both a longitudinal and a short-axis view of the fetal mediastinum.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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