A rapid structural degeneration of a porcine mitral valve.

A 73-year-old woman underwent both mitral and aortic valve replacements with porcine heart valve prostheses because of severe mitral regurgitation and severe aortic regurgitation. Ten months after surgery, maximal flow velocity of the aortic valve reached 4.6 m/sec and moderate mitral regurgitation was detected. Repeated mitral and aortic valve replacements with mechanical heart valves were performed. The excised mitral valve showed thinning of the 3 cusps, and 2 of them were perforated. There was pannus overgrowth on the flow surface of the porcine aortic valve. Histologic examination of the excised mitral valve revealed marked inflammatory changes with macrophages.