Abnormal motion of the mitral valve with pericardial effusion: Pseudo-prolapse of the mitral valve.

The echocardiograms of seven patients with large pericardial effusions were found to show posterior motion of the mitral leaflets in systole as seen in prolapse of the mitral valve. Repeat echocardiograms after resolution of the effusion revealed normal mitral valve motion. None of the patients had clinical evidence of prolapsed mitral valve. We postulate that a posterior swing of the heart within the pericardial fluid occurring in late systole causes posterior displacement of the mitral valve simulating a prolapsed valve.