Aortic mural thrombus: an occult source of arterial thromboembolism.

During a 28-year period from 1955 to 1983, two cases of massive repetitive arterial thromboembolism from nonaneurysmal aortic mural thrombus were diagnosed antemortem and successfully corrected at the University of California, Los Angeles Medical Center. Within the same time period, 48 cases of nonaneurysmal aortic mural thrombus were identified in 10,671 consecutive autopsies (0.45% incidence). Eight of these patients had evidence of distal embolization (17%), and three had major thromboembolic occlusions, which were considered the proximate cause of death (6%). The latter three patients represented 9% of autopsy-confirmed deaths from peripheral arterial thromboembolism. The diagnosis was established in a 49-year-old man and a 51-year-old woman after a long course marked by recurrent arterial embolization. Despite multiple evaluations, which included angiography, the diagnosis remained elusive until clinical suspicion resulted in complete biplane aortographic survey. Although the morphologic characteristics of this lesion are quite striking, subtle angiographic changes and lack of familiarity with the clinical presentation contribute to the difficulty and infrequency of diagnosis. This unique lesion comprises an important segment of the so-called cryptogenic sources of arterial embolization and can be corrected by a definitive surgical procedure.