Hypertrophic obstructive cardiomyopathy (HOCM) with dynamic left ventricular outflow tract obstruction (LVOTO) worsens with which maneuver during physical examination?

• A Standing up from squatting (decreases venous return, increases obstruction) ✓
• B Passive leg elevation (increases venous return)
• C Handgrip exercise (increases afterload)
• D Squatting position (increases preload and afterload)

Explanation

HOCM murmur (harsh systolic ejection murmur at LLSB) increases with maneuvers that decrease preload or afterload (Valsalva, sudden standing, dehydration, nitrates, tachycardia) — all reduce LV size, increasing dynamic LVOTO. Squatting increases both preload and afterload, which increases LV volume and reduces obstruction (murmur decreases). Standing from squatting suddenly reduces venous return, increasing obstruction. Handgrip increases afterload, which decreases the Venturi effect and reduces the murmur. This is opposite to fixed obstruction (AS) where murmur increases with increased cardiac output.

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

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Written and medically reviewed by the StethoPrep medical team.