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Hypertrophic cardiomyopathy on echo: asymmetric septal hypertrophy and SAM

Asymmetric septal hypertrophy (septum ≥15 mm, much thicker than the inferolateral wall), small hyperdynamic cavity, often SAM of the anterior mitral leaflet in mid-systole.

Watch it in the simulator →Practise random cases

Where to look

PLAX and PSAX for asymmetric septal thickness, apical 3-chamber and PLAX for SAM of the anterior mitral leaflet.

Typical wall-motion pattern

Example: Asymmetric septal HCM

All 17 segments thicken normally.

EF in this example: 70% (Normal (≥55%)).

1 Normal2 Hypokinetic3 Akinetic4 Dyskinetic5 Aneurysmal

Ejection fraction

Across 24 simulated cases of this pattern the true EF ranged from 68% to 74% (median 71%, Normal (≥55%)). Every case in the simulator is different, so practise until your visual estimate lands in the right 5% range.

Teaching points

HCM: asymmetric septal thickening (≥15 mm), small hyperdynamic cavity, with systolic anterior motion (SAM) of the mitral leaflet. Hypertrophied segments may thicken less than expected but here are graded normal.
HCM: asymmetric septal thickening (≥15 mm), small hyperdynamic cavity. Hypertrophied segments may thicken less than expected but here are graded normal.
Ventricular ectopics: the premature beat is weak and dyssynchronous and the beat after the pause is stronger. Judge EF and wall motion on normal sinus beats only.
Atrial fibrillation: filling and EF vary from beat to beat. Average at least five beats, or use an index beat (one that follows two similar RR intervals), and avoid beats after a very short RR interval.

Common pitfalls

Thick segments can thicken less; do not confuse a thick, poorly thickening septum with a septal infarct.

Try it now: open the Hypertrophic cardiomyopathy (asymmetric septal) example with the segment overlay, then test yourself in Practice where cases are random and graded against the exact answer.