Mitral Valve Prosthesis

All three struts of this large prosthetic valve in the mitral position can be seen. One strut is obstructing the left ventricular outflow tract.

Mechanical prostheses are composed of non-physiological biomaterials with caged balls, tilting discs, or hinged semicircular flaps. Tissue valves consist of chemically treated animal tissue mounted on a frame. Over the long haul there are frequent complications. Thrombus formation with local obstruction or embolism can be largely prevented by long-term anticoagulation but at a price of the risk of bleeding. Infective endocarditis may develop at the prosthesis-tissue interface causing an abscess. Structural deterioration may occur. Balls have been known to fly from the cage. Balls and discs have stuck in a fixed position. The animal tissue used can undergo degeneration and calcification. Overgrowth of fibrous tissue can cause dysfunction. Hemolysis sometimes occurs as a result of shearing forces. The prosthesis may be improperly placed or be of disproportionate size, e.g. a large mitral valve prosthesis partially obstructing the left ventricular outflow tract, as in this case.