Echocardiographic and Flow Visualization Studies of the Mechanism for Systolic Anterior Motion of the Mitral Valve In Hypertrophic Cardiomyopathy
Obstructive hypertrophic cardiomyopathy is characterized by a thickened interventricular septum and systolic anterior motion (SAM) of the mitral valve. This study tested a new hypothesis for SAM which stresses primary structural abnormalities of the papillary muscles using an in vitro model of the left ventricle. Echocardiographic observations revealed creation of SAM by anterior and inward displacement of the papillary muscles. Septal thickening alone, the basis of the currently accepted Venturi theory, did not produce SAM. Flow visualization studies confirmed the importance of drag forces in the maintenance of SAM as streamlines were observed to impact on the residual anterior leaflet which was interposed into ventricular outflow.
KeywordsMitral Valve Outflow Tract Papillary Muscle Hypertrophic Cardiomyopathy Axis View
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