Thrombosed Björk-Shiley mitral prostheses.

During a 4.5-year period ending in January 1978, 224 patients were discharged from the hospital after Bjork-Shiley mitral valve replacement. Follow-up records for all patients were available until the last date of inquiry on March 31, 1978. Twelve patients presented to us 3-43 months (mean 17 months) after surgery with thrombosis of their mitral prostheses. A clinical syndrome consisting of acute onset of ischemic or pleuritic chest pain, dyspnea and right- sided cardiac failure is described. The prosthetic sounds, especially the opening click, are invariably absent or markedly muffled, but definitely abnormal mitral murmurs are infrequently detected. The echocardiogram is a useful adjunct in confirming the diagnosis. Total thrombotic encapsulation of the prosthesis may supervene within hours or days and is invariably fatal unless there is surgical intervention. Our first patient died because we failed to make an immediate correct diagnosis. Thereafter, the early recognition of the clinical features resulted in successful valve replacement.