Question

A systolic murmur that becomes more prominent on standing is a feature of

• A. Valvular aortic stenosis
• B. Rheumatic mitral regurgitation
• C. Idiopathic hypertrophic subaortic stenosis (HOCM)
• D. Pulmonary stenosis

Hint:

Ask whether the obstruction in each condition is a fixed narrow valve or something that changes shape with the size of the ventricle.

Answer 1

The Correct Option is C

This question tests the key bedside trick for separating dynamic outflow obstruction from fixed valvular stenosis: how the murmur responds to a fall in preload.

1. Valvular aortic stenosis: a fixed obstruction - less flow across it on standing means a softer murmur, the opposite of what is described.
2. Rheumatic mitral regurgitation: its murmur is not characteristically preload-dependent in this way.
3. Idiopathic hypertrophic subaortic stenosis: obstruction is dynamic and worsens as the left ventricle empties into a smaller cavity with reduced preload, so the murmur gets louder on standing - the correct match.
4. Pulmonary stenosis: another fixed valvular lesion that does not intensify with standing the way a dynamic obstruction does.

Correct answer: Idiopathic hypertrophic subaortic stenosis (HOCM).