PARADOXICAL EMBOLISM AND CRYPTOGENIC STROKE

Paradoxical embolism is defined as venous thrombosis causing systemic embolization through a right-to-left shunt. It can involve multiple organs simultaneously. Despite reports of the clinical presentation and devastating consequences for more than a century, this diagnosis continues to be frequently missed. It should be considered whenever there is an arterial embolism from an unidentified source in the presence of a concomitant venous thromboembolic phenomenon. While contrast echocardiography facilitates clinical recognition of paradoxical embolism, the optimum approach to diagnosis requires clarification. Recommendations for treatment vary with the certainty of diagnosis and should be individualized. Primary therapy is anticoagulation, with thrombolytics considered in carefully selected individuals, but there is little published information regarding long-term treatment and outcomes. Events that give rise to transient right atrial hypertension may result in a right-to-left shunt through a patent foramen ovale, possibly allowing a venous thrombus access to the arterial circulation; this should be considered when the source of emboli is unknown, particularly in young patients. It is not yet defined whether prophylactic closure of the foramen ovale is beneficial.

Keywords: paradoxical embolism, pulmonary embolism, cryptogenic stroke, venous thromboembolism, right-to-left shunt, foramen ovale.