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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 rightsided 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.In addition to the first patient, there were 18 deaths among the 224 patients. Although none of these 18 patients was examined by us, hospital records, telephone inquiries or necropsy reports revealed that six of them died because of thrombotic occlusion of their mitral prostheses.We conclude that poor anticoagulant control was the principal factor predisposing to prothetic thrombosis in our experience. Eighteen patients (8%) sustained this complication during the study. Neither the original mitral valve lesion nor the size of the Bj6rk-Shiley prosthesis was relevant. We have discontinued using the Bj8rk-Shiley prosthesis for mitral valve replacement when we cannot be certain of ideal control of anticoagulant therapy.