[Arterial embolism of venous origin: a clinical entity to keep always in mind]

In patients with unexplained arterial embolism or unexplained cerebral vascular accidents, a diagnosis of paradoxical embolism should be taken into consideration. It consists in the passage of an embolus, originating in the venous system or the right side of the heart, via an abnormal right to left channel, into the systemic circulation. In the majority of cases the abnormal communication is a patent foramen ovale; its incidence varies from 6% to 29% in unselected autopsies. The diagnosis of paradoxical embolism requires the presence of four Johnson's criteria. Nowadays the diagnostic procedures have been simplified by introducing non-invasive techniques based on ultrasound evaluation. The treatment of paradoxical embolism must be individualized and consists above all in the use of anticoagulants. Here we report a case of right leg paradoxical embolism in a young woman who had been operated on three months earlier for breast cancer. After ilio-femoro-popliteal thromboembolectomy, Doppler of the lower limb veins was performed. The presence of iliac venous thrombosis led to a suspicion of paradoxical embolism, which was then confirmed by the demonstration of a patent foramen ovale. The diagnosis of paradoxical embolism is important because the condition is associated with significant morbidity and mortality rates.