XXXX causes systolic anterior motion of the mitral valve. Experimental validation and insights into the mechanism of subaortic obstruction.

@entity1 @entity339 @entity1184 @entity235 @entity9467 @entity299 @entity1121 @entity121
BACKGROUND: @entity299 ( @entity299 ) of the mitral valve in @entity1121 ( @entity1121 ) has generally been explained by a Venturi effect related to @entity1184 , causing outflow tract narrowing and high velocities. @entity1 with @entity1121 , however, also have primary @entity9467 , including anterior and inward or central displacement of the papillary muscles, and leaflet elongation. These findings have led to the hypothesis that changes in the mitral apparatus can be a primary cause of @entity299 by altering the forces acting on the mitral valve and its ability to move in response to them. Despite suggestive observations, however, it has never been prospectively demonstrated that such changes can actually cause @entity299 . METHODS AND RESULTS: To test this hypothesis in vivo, anterior @entity121 was created in 7 @entity235 studied by echocardiography, with controlled cardiac output and heart rate. In all 7 @entity235 , @entity121 caused @entity299 , with an outflow tract gradient (33 +/- 19 mm Hg) and @entity339 in 6. As in @entity1 with @entity1121 , the mitral valve was displaced anteriorly and the coaptation point shifted toward the insertion of the leaflets, creating longer distal residual leaflets that moved anteriorly. CONCLUSIONS: Primary changes in the mitral apparatus can cause @entity299 without @entity1184 . In this model, @entity299 appears to be determined by the ability of the leaflets to move anteriorly ( @entity121 causing slack and increased residual leaflet length) and their interposition into the outflow stream by anterior displacement, determining the direction of this motion. Geometric factors observed in @entity1121 and in @entity1 with @entity299 without @entity1121 can therefore play a primary role in causing @entity299 .
