Primary aortic non-occlusive thrombus is a rare entity and not commonly encountered in routine practice. These thrombi may be associated with atherosclerotic plaques or may evolve de novo in the aorta. In patients with established atherosclerotic disease upon which the thrombus is superimposed, this disease may pursue a more aggressive course. In patients where thrombus is the only finding, an underlying hypercoaguable state has been postulated predisposing to thrombus formation. There are also reports of de novo aortic thrombosis in patients with protein C and protein S deficiency and in neonates too.
Earlier, it was believed that a primary thrombus developed due to the paradoxical effects of heparin therapy. However, a study by Williams, et al in 1981 identified certain risk factors that predispose a patient to aortic thrombosis and these included heart disease, recent thrombophlebitis, heparin therapy, abdominal atherosclerosis and postoperative status. Most of these patients had serious medical problems and at least two of the ‘risk factors’. The patient demonstrated here also had multiple medical problems and two of the risk factors mentioned above.
Aortic thrombus can be a potential source for peripheral emboli and hence needs to be recognized and treated in such a clinical setting. A morphologically normal aorta with echogenic material in its lumen and varying degrees of aortic occlusion is identified. The entire length of aorta must be scanned in order to completely evaluate the extent of disease. Ultrasound with color Doppler is diagnostic and is also useful for monitoring these patients in cases where the aorta is well visualized. Surgical thrombectomy, thrombolysis and systemic anticoagulation are the therapeutic options. In many patients treatment with anticoagulants has resulted in complete resolution of the thrombus.
Thus if a patient presents with symptoms of embolic disease and a non cardiac source is suspected, a thorough evaluation of the aorta is indicated.