Escape of a leaflet from a St. Jude Medical prosthesis in the mitral position.

Twenty-three months after mitral valve replacement for mitral stenosis with a St. Jude Medical heart valve prosthesis size 31, a 29-year-old man suddenly went into a profound cardiogenic shock and pulmonary edema due to escape of one of the leaflets from the prosthesis. At emergency operation the valve was replaced with another type of prosthesis. The escaped leaflet was retrieved from the abdominal aorta and was found to be intact. The cause of the escape was found to be a fracture in the pivot area. Further examination with optic and scanning electron microscopy revealed an old fracture at the base of the pivot covered with organic material and another fracture at the top of the pivot area not covered with organic material and therefore probably very recent and responsible for the break-off of part of the area and subsequent escape of the leaflet. The cause of the primary fracture is unknown.