SAM
Also written as: SAM — Systolic Anterior Motion
Systolic anterior motion of the mitral valve, causing dynamic left ventricular outflow tract obstruction.
Full Definition
Systolic anterior motion refers to the abnormal forward movement of the mitral valve leaflets during systole, particularly the anterior leaflet or chordal structures. SAM creates dynamic obstruction of the left ventricular outflow tract and is a hallmark finding in hypertrophic cardiomyopathy. The degree of SAM correlates with the severity of outflow obstruction and associated mitral regurgitation. Echocardiographic assessment involves measuring the distance between the mitral valve and interventricular septum during systole. SAM can be provoked or worsened by factors that reduce preload or afterload, such as Valsalva maneuver or certain medications.
Usage
Usage note: Always clarify as 'SAM of the mitral valve' to distinguish from other uses of the acronym.
In Context
- "Severe SAM was observed with mitral-septal contact distance of 2mm during peak systole." — Hypertrophic cardiomyopathy evaluation
- "The degree of SAM increased significantly with Valsalva maneuver, consistent with dynamic obstruction." — Echocardiography stress study