Which congenital heart defect is associated with a "boot-shaped" heart on x-ray?

A "boot-shaped" heart on chest X-ray is a classic radiographic finding associated with Tetralogy of Fallot. This congenital heart defect comprises four components: ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and an overriding aorta. The right ventricular hypertrophy leads to a characteristic appearance of the heart silhouette on X-ray, resembling a boot due to the upward lift of the cardiac apex and the narrowing at the base.

In contrast, other congenital heart defects have differing X-ray findings. For instance, ventricular septal defect may present with cardiomegaly due to volume overload but does not have a specific shape. Atrial septal defect typically results in right heart enlargement but lacks the defining boot shape seen in Tetralogy of Fallot. Coarctation of the aorta is often associated with indirect signs such as rib notching or a "figure 3" sign due to collateral circulation, rather than a boot-shaped heart.

Thus, the association of Tetralogy of Fallot with a "boot-shaped" heart is due to the right ventricular hypertrophy and the overall heart configuration that results from the combination of its anatomical features.