Invited commentary.
D006350:Heart Valve Prosthesis / Q000706:statistics & numerical data*; D006801:Humans; D008944:Mitral Valve Insufficiency / Q000175:diagnosis / Q000208:ethnology* / Q000601:surgery; D008946:Mitral Valve Stenosis / Q000175:diagnosis / Q000208:ethnology* / Q000601:surgery