An unusual form of mitral insufficiency accompanying atrial septal defect.

An unusual case of atrial septal defect secundum type, associated with intermittent severe mitral insufficiency due to billowing anterior mitral leaflet, in a 56-year old female is described. The degree of mitral insufficiency ranged from severe to none. This phenomenon manifested itself by an intermittent systolic apical thrill and intermittent mitral regurgitation on angiocardiography. Pulling the anterior mitral leaflet at operation through the atrial septal defect demonstrated that this leaflet could be caught in the left atrium, thus causing intermittent mitral insufficiency. Closure of the atrial septal defect and replacement of the mitral valve was performed.