What is a distinct feature of the heart on X-ray in a patient with tetralogy of Fallot?

In patients with tetralogy of Fallot, the characteristic finding on an X-ray is a boot-shaped heart. This distinct appearance is primarily due to the right ventricular hypertrophy and the position of the heart in the chest. The ventricle's muscular walls become thickened, contributing to the unique contour that resembles a boot.

Tetralogy of Fallot consists of four cardiac anomalies: ventricular septal defect (VSD), pulmonary stenosis, overriding aorta, and right ventricular hypertrophy. As pressure in the right ventricle increases because of the outflow obstruction, the adaptation leads to the boot-like appearance on imaging. This finding can help clinicians visually identify the condition even before conducting more invasive diagnostic tests such as echocardiography or cardiac catheterization.

In contrast, other features like cardiomegaly generally suggest volume overload or other types of heart disease rather than specifically highlighting the unique morphology associated with tetralogy of Fallot. Similarly, an enlarged right atrium or straightening of the cardiac silhouette may not be particularly informative in this context and do not convey the classic image associated with this congenital heart defect.