Mitral valve training › Guides › SAM-related MR in HCM
Systolic anterior motion (SAM) of the mitral valve on echo
What to look for: A basal septal knob; the anterior leaflet swings into the outflow tract.
Watch it in the simulator →Practise random casesSAM is outside Carpentier’s classification: the anterior leaflet is pulled into the outflow tract. Jet: posterior, mid-to-late systolic.
Key findings
- Hypertrophic cardiomyopathy: a wall ≥15 mm in any segment, not explained by loading conditions.
- Systolic anterior motion (SAM): the anterior leaflet (or its chords) is drawn into the LV outflow tract in mid systole, obstructing it and pulling the leaflets apart, with a posteriorly directed, mid-to-late systolic MR jet.
- On CW, the outflow signal is late-peaking (dagger-shaped); the MR signal is faster and starts earlier: keep the two apart.
- An anterior or central MR jet suggests an intrinsic mitral valve problem as well.
Grading
- LV outflow tract obstruction: a peak gradient ≥30 mmHg; ≥50 mmHg is haemodynamically important. If the resting gradient is <50 mmHg, provoke it (Valsalva, standing, exercise).
- Grade the MR with the usual signs; it falls when the obstruction is relieved.
Pitfalls
- SAM also occurs without HCM: after mitral repair, with a small, hyperdynamic LV, or on inotropes.
In the simulator every case varies the anatomy, the jets and the measurements: watch the lesion in Learn, then grade new cases in Practice and compare your answer with the exact one.
See also: Hypertrophic cardiomyopathy and SAM in the LV trainer.
Related
Single-scallop prolapse · Surgical repair (annuloplasty ring)
Educational simulation to use under the supervision of a clinical tutor — not for clinical use.