Paradoxical Embolism

Paradoxical embolism describes an event in which embolic material originates in the venous system or right heart, passes through any right-to-left shunt, and ends in the arterial system. Although this sequence of events usually is thought to occur with venous thrombus migrating through a patent foramen ovale (PFO), any material (e.g., air, tumor, fat, foreign body) migrating through any right-to-left shunt (e.g., ventricular septal defect, pulmonary arteriovenous fistula, patent ductus arteriosus) is also correctly referred to as paradoxical embolism.

Paradoxical embolization should be considered as part of the differential diagnosis in any patient who comes to the hospital with simultaneous pulmonary embolism or deep vein thrombosis (DVT) and acute ischemia in any arterial bed. Since the turn of the century, considerable attention has been placed on the role of PFO closure in treating and preventing cerebrovascular events. The widespread use of echocardiography, the relatively high incidence of PFO in the normal population, and financial interest has created a milieu in which enthusiasm in treating this entity continues. Case reports and case-control studies make up the bulk of published literature, although larger, well-designed studies have not shown any benefit to closing a PFO. Still, the mainstay of treatment is the same as for any embolic event and consists of evaluating the source, treating arterial bed ischemia, and instituting anticoagulation.