Eustachian valve, interatrial shunt, and paradoxical embolism.

Randomized clinical trials demonstrate that percutaneous closure of the patent oval foramen is a safe and effective treatment for secondary prevention of cryptogenic stroke in selected patients. The Eustachian valve is generally considered an incidental finding without any significant pathophysiological consequences in adults. However, a persistent Eustachian valve, particularly a prominent one, is significantly more prevalent in patients with patent oval foramen and cryptogenic stroke, and is associated with adverse outcomes following percutaneous closure. Therefore, the Eustachian valve may not be an incidental finding or an innocent bystander. By directing the blood flow from the inferior caval vein to the interatrial septum, the persistence of a Eustachian valve may prevent spontaneous closure of the oval foramen, and predispose to paradoxical embolism during adulthood. The Eustachian valve should be considered an adjunctive risk factor for paradoxical embolism in patients with patent oval foramen. Furthermore, the Eustachian valve has been included in several risk prediction models to identify patients at the highest risk of paradoxical embolism and such patients may benefit the most from an intervention.