S4 can rarely be associated with right ventricular hypertrophy in which condition?

• A. Mitral stenosis
• B. Atrial septal defect
• C. Tricuspid regurgitation
• D. Pulmonary embolism

Answer: (A)

S4 arises from atrial contraction into a noncompliant ventricle. In this scenario, mitral stenosis raises left atrial pressure and, over time, leads to pulmonary hypertension. The resulting increased afterload on the right ventricle causes right ventricular hypertrophy and stiffening. When the atria contract against this stiffer RV, a right-sided S4 can be heard, though it’s a rare finding. The other conditions listed don’t typically create a stiff, hypertrophied right ventricle in the same way: ASD and pulmonary embolism more often produce signs of volume overload or acute strain, while tricuspid regurgitation mainly presents with a regurgitant murmur rather than a left-to-right S4.