Dysfunction of a bileaflet mechanical valve in mitral position: absence of symptoms despite a completely fixed leaflet.

We report the case of 62 year-old asymptomatic woman with a bileaflet mechanical prosthesis implanted 1 year ago. Routine transthoracic echocardiography (TTE) showed that one leaflet was fixed in semi-closed position, which was confirmed by transesophageal echocardiography (TEE) and cinefluoroscopy. The paradoxical absence of symptoms despite a complete restriction of one leaflet may be due to the fact that this patient had a very small body surface area and received a prosthesis with an excellent hemodynamic performance. The presence of a large compliant left atrial chamber may have also contributed to limit the effects of valve dysfunction on the pulmonary circulation.