MITRAL ANNULAR FLEXIBILITY

An analysis of three-dimensional movement of the mitral valve annulus (MVA) may address the question of geometrical change after mitral valv e repair to preserve mitral annular function. Conventionally, annular contraction has been studied for this purpose. We investigated this ge ometrical change occurring in the anterior half of the MVA and discuss its clinical significance. Three-dimensional images of the MVA during systole were reconstructed from magnetic resonance images of eight no rmal subjects. The posterior half of the MVA exhibited translational m otion. We assume that this portion, exhibiting translational motion as well as contraction, purely follows the motion of the left ventricula r contraction. Compensating for the discrepancy between the motion of the aortic root and that of the posterior half of the MVA, the anterio r half exhibited a flexible change in shape during systole, thus maint aining a sufficient left ventricular outflow tract (LVOT). The increas e in the extent of displacement of the anterior MVA from the posterior half of the MVA during systole, which was 3.6 +/- 1.0 mm (mean +/- SD ), indicates the annular flexibility. The preservation of annular flex ibility may prevent LVOT obstruction. Further geometrical analysis of patients after mitral repair will clarify annular function as presente d in this article.