Cyanotic Congenital Heart Disease
Tetralogy of Fallot The cardiac silhouette has a characteristic boot shape (coeur-en-sabot), with elevation of the cardiac apex due to right ventricular hypertrophy and concavity of the left upper cardiac border (pulmonary bay) due to a small pulmonary trunk. The pulmonary vascular markings may be normal or reduced, depending on the severity of right ventricular outflow obstruction.
Pulmonary atresia with ventricular septal defect The characteristic boot-shaped heart (coeur-en-sabot) is more common in pulmonary atresia with ventricular septal defect than in tetralogy of Fallot. When pulmonary blood flow is limited as a result of constriction of the arterial duct or stenosed aortopulmonary collaterals, the vascular markings are diminished (pulmonary oligaemia). In the presence of multiple large aortopulmonary collaterals, the pulmonary vascular markings appear uneven.
Transposition of the great arteries The characteristic radiographic features include an oval cardiac silhouette (‘egg-on-side' appearance), a narrow mediastinal shadow, and increased pulmonary vascular markings. The abnormal antero-posterior relationship of the aorta and pulmonary artery and stress-related thymic involution account for narrowing of the superior mediastinum.
Ebstein's anomaly of the tricuspid valve Massive cardiomegaly is characteristic in severe Ebstein's malformation due to significant dilation of the right atrium and the atrialized portion of the right ventricle. The pulmonary vascular markings are diminished. In children with milder forms of Ebstein's malformation, the cardiac size may only be mildly enlarged or even normal.