**Core Concept**
The 'coeur en sabot' or boot-shaped heart is a characteristic radiographic appearance of the heart in patients with right ventricular hypertrophy, often due to pulmonary hypertension or other conditions that lead to increased pressure and workload on the right ventricle.

**Why the Correct Answer is Right**
In right ventricular hypertrophy, the right ventricle becomes thickened and enlarged, causing the heart to take on a characteristic boot-shaped appearance on chest radiographs. This occurs because the right ventricle is unable to accommodate the increased volume and pressure, leading to a distinctive silhouette on the cardiac silhouette. The boot-shaped appearance is due to the prominence of the right ventricle, which is best visualized on a left anterior oblique view.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not describe a characteristic radiographic appearance of the heart. A 'coeur en sabot' or boot-shaped heart is a specific finding associated with right ventricular hypertrophy.
**Option B:** This option is incorrect because it does not accurately describe the boot-shaped heart. Tetralogy of Fallot is a cyanotic congenital heart disease characterized by four components, but it does not typically result in a boot-shaped heart.
**Option C:** This option is incorrect because it does not accurately describe the boot-shaped heart. A 'coeur en sabot' or boot-shaped heart is a radiographic finding, not an electrocardiographic finding.

**Clinical Pearl / High-Yield Fact**
A boot-shaped heart is a classic radiographic sign of right ventricular hypertrophy and should be remembered in the context of evaluating patients with suspected pulmonary hypertension or other conditions that may lead to increased pressure and workload on the right ventricle.

**Correct Answer: D.**