Complications of supra-annular mitral valve placement in infants.

Two infants underwent supra-annular placement of prosthetic mitral valves. The objective of this strategy was to insert a larger valve and delay replacement. This approach was initially successful but by two and three years later the patients developed impairment of cardiac function. The prosthesis decreased the volume and compliance of the left atrium causing high left atrial and pulmonary venous pressures. The "ventricularised" atrium below the prosthesis dilated. In neither case was it possible to delay second valve replacement.