Acute thrombotic obstruction with Björk-Shiley valves: diagnostic and surgical considerations.

Eight patients have had thrombotic obstruction of a prosthetic valve since 1971, six mitral valves and two aortic. All eight patients had a Björk-Shiley valve. During the same period 159 Björk-Shiley valves were placed, 85 in the mitral and 74 in the aortic area. This represents a valve thrombotic occlusive incidence of 4.4 percent in our series, 5.9 percent of mitral and 2.7 percent of aortic prostheses. Among the six patients with mitral prostheses only one survived. The two patients with occluded aortic valves survived. The onset of symptoms was very abrupt in most patients and progressed very rapidly. Acute pulmonary edema was observed in five patients. Anticoagulation was considered inadequate in all patients. Aspirin or dipyridamole was being used in seven patients at the time of thrombosis. The data indicate a high frequency of thrombotic occlusion of Björk-Shiley valves in the absence of full anticoagulation with warfarin derivatives and emphasizes the urgent need for surgery once valve thrombosis is suspected.