A 28-year-old man with hypertrophic obstructive cardiomyopathy has a systolic murmur at the left sternal border. Which manoeuvre will predictably increase the intensity of his murmur?

• A Squatting from standing
• B Standing abruptly after squatting ✓
• C Sustained handgrip
• D Passive leg raising

Explanation

Abrupt standing reduces venous return and preload, shrinking left ventricular cavity size and bringing the hypertrophied septum closer to the mitral leaflet, which worsens the dynamic outflow obstruction and intensifies the murmur. Squatting, handgrip, and leg raising all increase preload or afterload, enlarging the ventricular cavity and softening the murmur. This preload dependence distinguishes it from fixed lesions such as aortic stenosis.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.