Three case histories of patients with malfunctions of Smeloff-Cutter mitral ball valve prostheses are presented here - one underwent successful replacement. The clinical diagnosis was made by observing a marked variation in the A2OC interval and intermittent absence of the opening click. Phonocardiograms were diagnostic in all three cases. while echocardiograms and even angiograms did not uniformly diagnose prosthetic valve dysfunction. Periodic phonocardiographic evaluations may be helpful in early detection of the prosthetic valve dysfunction. Once the diagnosis is established, immediate surgical treatment is imperative to prevent sudden death
