Approximately 1 million people suffer a symptomatic stroke each year in the United States with 160,000 of these considered cryptogenic strokes. A stroke is classified as cryptogenic when no cause is identified after extensive evaluation. This occurs in 25-40% of strokes in young adults.

Relatively recently, paradoxical embolism through an atrial communication such as a patent foramen ovale (PFO) or atrial septal defect (ASD) has been recognized as a cause cerebral ischemic events previously considered cryptogenic. Approximately 40-70% of patients suffering cryptogenic strokes have PFOs whereas the incidence of PFOs in the general population is 10-23%. Stroke patients with PFOs are also at risk for recurrent cerebral thromboembolic events at a rate of 3.4-3.8% per year.

Mechanistic theories of paradoxical embolism include right to left shunting of venous thromboemboli and the PFO acting as a tunnel within which thrombus can develop secondary to stasis with embolization occurring during periods of valsalva.

Diagnosis of a PFO or ASD can be made with transthoracic or transesophageal echocardiography using agitated saline with bubbles for a contrast agent.

Current management includes medical therapy with antiplatelet or anticoagulant medication, surgical closure and the more recent development of transcatheter closure with a variety of closure devices. Studies investigating transcatheter device closure of PFOs have been encouraging.

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