The distinct feature of the pulmonary atresia with ventricular septal defect that differentiates it from Tetralogy of Fallot is the absence of a right ventricular outflow and severe abnormalities of the pulmonary circulation. Since this is an anomaly that develops very early in embronic life, the vascularization to the lungs is not from a progressively stenosing pulmonary artery, but entirely from the systemic arterial circulation via the "major aortopulmonary collateral arteries" . The presence of major aorto-pulmonary collateral arteries from the descending aorta directly to the lungs worsens the neonatal course, and they are typical in this anomaly .
Images 1, 2
: Four chamber view of the heart showing deviation of the cardiac axis to the left (87°), ventricular septal defect with overriding aorta taking the blood from both ventricles (red flow). Image 2 represents a fusion of the image 1 with drawings explaining position of the fetus and placement of the heart within the chest.
Images 3, 4
: Aortic arch with reversed flow within the ductus arteriosus (white arrow on the image 4).
Images 5, 6, 7, 8
: Aortic arch (Images 5, 6) and descending aorta (Images 7, 8). Reversed flow at the level of ductus arteriosus (white arrow on the image 6) and origin of the major collateral arteries (yellow arrow on the image 6 and white arrow on the image 8) can be seen.
Images 9, 10
: Aortic arch.
Images 11, 12
: Aortic arch and descending aorta with the origin of the major collateral arteries (yellow arrow on the image 12).
Images 13, 14
: Aortic arch and descending aorta (displayed by color Doppler STIC mode) with the origin of the major collateral arteries (yellow arrow on the image 14).
Images 15, 16
: Color Doppler - three-vessel trachea view of the heart showing dilated aorta with reversed flow at the level of the ductus arteriosus (white arrow on the image 16).
: Gray scale - three-vessel trachea view of the heart showing dilated aorta and absent pulmonary artery.
Images 18, 19
: Gray scale images showing abnormal shape of the lumbar spine due to multiple hemivertebrae.
Images 20, 21
: 3D scans of the fetal spine showing hemivertebrae at the level of the lumbar spine.
1. Alfred Abuhamad, Rabih Chaoui. A practical guide to fetal echocardiography: normal and abnormal hearts. 2nd ed. Philadelphia, PA : Wolters Kluwer Health/Lippincott Williams & Wilkins, ©2010.
2. P. Jeanty, R. Chaoui, J.Pilu, R. Romero. Fetal echocardiography part II: the anomalies. DVD. 2006.