This document discusses grading of systolic anterior motion (SAM) of the mitral valve based on the amount of contact between the mitral valve and ventricular septum during systole. It defines 4 grades of SAM based on the minimum distance between the structures and duration of contact, with Grade I having no contact and a distance over 10mm and Grade IV having prolonged contact over 30% of systole. It notes SAM is an underrecognized cause of cardiovascular collapse that can be triggered by reductions in preload or increased catecholamines, and is best diagnosed by echocardiography with acute treatment involving volume, vasopressors or adrenergic blockers.

1. Systolic Anterior Motion of the Mitral Valve with
Left Ventricular Outflow Tract Obstruction
Sine qua non of obstructive cardiomyopathy

2. Echocardiographic Grading of Systolic
Anterior Motion of the Mitral Valve
I
No mitral leaflet-septal contact, minimum distance between the
mitral valve and the ventricular septum during systole 10 mm
II
No mitral leaflet-septal contact, minimum distance between the
mitral valve and the ventricular septum during systole <10 mm
III
Brief mitral leaflet-septal contact (<30% of systole time)
IV
Prolonged mitral leaflet-septal contact (>30% of systole time)

3. SAM Grade I
No mitral leaflet-septal contact, minimum distance between the mitral
valve and the ventricular septum during systole 10 mm

4. SAM Grade II
No mitral leaflet-septal contact, minimum distance between the mitral
valve and the ventricular septum during systole <10 mm

5. SAM Grade III
Brief mitral leaflet-septal contact (<30% of systole time)

6. SAM Grade IV
Prolonged mitral leaflet-septal contact (>30% of systole time)

7. Perspective
Under-recognized cause of acute perioperative and stress induced
cardiovascular collapse
Triggers: Relative or absolute reductions in left ventricular preload, such as
hypovolemia, anesthetic drug-mediated venodilation, increased
catecholamine concentrations and exercise
Diagnosis: Echocardiography & transesophagial most suitable
Acute treatment : infusion of volume/vasopressors/adrenergic blockers

8. Enjoy this Grade IV SAM
https://youtu.be/VXI2r0qujs0