Aortic stenosis vs Hypertrophic cardiomyopathy
How to tell Aortic stenosis and Hypertrophic cardiomyopathy apart when a board question makes them look alike.
AS is fixed obstruction with pulsus parvus et tardus; HCM is dynamic obstruction with brisk/bifid pulse and louder murmur when preload falls.
Side by side
Crescendo-decrescendo systolic murmur at the right upper sternal border radiating to the carotids.
Dynamic systolic murmur that increases with Valsalva or standing and decreases with squatting.
Fixed calcific or congenital obstruction limits outflow across the aortic valve.
Asymmetric septal hypertrophy causes dynamic left ventricular outflow obstruction.
Delayed carotid upstroke and valve calcification support aortic stenosis.
Family history, syncope in a young athlete, septal hypertrophy, and brisk/bifid carotid pulse support HCM.
The trap
Both are crescendo-decrescendo systolic ejection murmurs and both cause exertional syncope, so murmur shape does not decide. The fastest discriminator is the response to preload. Valsalva or standing makes HCM LOUDER (less LV volume worsens outflow obstruction) and AS SOFTER (less stroke volume across the valve). Squatting or handgrip makes HCM SOFTER and AS LOUDER. The carotid seals it: pulsus parvus et tardus is AS; a brisk bifid pulse is HCM.
Watch it explained
The repair move
Use maneuvers and pulse: Valsalva/standing makes HCM louder, squatting/handgrip makes HCM quieter, and AS has a delayed weak carotid upstroke.
Try a free question
CoreAn older patient has exertional syncope, a crescendo-decrescendo systolic murmur at the right upper sternal border, radiation to the carotids, and delayed carotid upstroke. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Aortic stenosis. Fixed outflow obstruction with carotid radiation and delayed upstroke points to aortic stenosis.
Why the other choices are tempting
- B. HCM is dynamic and gets louder with reduced preload.
- C. Mitral regurgitation is holosystolic at the apex radiating to the axilla.
- D. Aortic regurgitation is early diastolic.
- E. Pulmonic stenosis is heard at the left upper sternal border.
Flashcards
Tap a card to flip it.
What is the fastest separator for Aortic stenosis vs Hypertrophic cardiomyopathy?
AS is fixed obstruction with pulsus parvus et tardus; HCM is dynamic obstruction with brisk/bifid pulse and louder murmur when preload falls.
What clue should make you choose Aortic stenosis?
Crescendo-decrescendo systolic murmur at the right upper sternal border radiating to the carotids.
Quick answers
What is the fastest way to tell Aortic stenosis from Hypertrophic cardiomyopathy?
AS is fixed obstruction with pulsus parvus et tardus; HCM is dynamic obstruction with brisk/bifid pulse and louder murmur when preload falls.
What is the key clue for Aortic stenosis?
Crescendo-decrescendo systolic murmur at the right upper sternal border radiating to the carotids.
What is the key clue for Hypertrophic cardiomyopathy?
Dynamic systolic murmur that increases with Valsalva or standing and decreases with squatting.
What is the common trap with Aortic stenosis vs Hypertrophic cardiomyopathy?
Both are crescendo-decrescendo systolic ejection murmurs and both cause exertional syncope, so murmur shape does not decide. The fastest discriminator is the response to preload. Valsalva or standing makes HCM LOUDER (less LV volume worsens outflow obstruction) and AS SOFTER (less stroke volume across the valve). Squatting or handgrip makes HCM SOFTER and AS LOUDER. The carotid seals it: pulsus parvus et tardus is AS; a brisk bifid pulse is HCM.