Early diastolic sound associated with mitral valve prolapse.

A patient with the prolapsing mitral valve syndrome demonstrated a most striking early diastolic sound. Noninvasive study with phonocardiograms, external pulse recordings, and echocardiograms lead us to believe that the sound may be related to the initial opening movement of the mitral valve. To our knowledge, such a mechanism for the production of a diastolic sound has not been previously reported.