What cardiac condition is associated with a "boot-shaped" heart on x-ray?

The term "boot-shaped" heart on an x-ray is classically associated with Tetralogy of Fallot. This appearance is primarily due to the right ventricular hypertrophy that occurs as a result of the right ventricular outflow obstruction, which is one of the key features of the condition. In Tetralogy of Fallot, the heart has an abnormal shape due to four defining defects: ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and an aorta that overrides the ventricular septum. The right ventricular hypertrophy contributes to the distinctive boot shape, often characterized by a narrow base and a pointed apex.

In contrast, while pericardial effusion can cause an enlarged cardiac silhouette, it does not create a specific boot shape. Coarctation of the aorta primarily presents with other changes depending on the severity and location of the constriction, including rib notching or differential blood pressures in the upper and lower extremities, but does not result in a boot-shaped heart. Lastly, primary pulmonary artery hypertension may appear with right ventricular enlargement or other findings, but it does not produce a typical boot shape on an x-ray. Therefore, the characteristic "boot-shaped" heart is a hallmark of Tetralogy of Fall