TEE of PFO

Systolic and diastolic views from a transesophageal echocardiogram (TEE) showing a "flap" of atrial septal tissue covering the patent foramen ovale (PFO). In early systole, the flap opens and the foramen ovale becomes patent, allowing right-to-left shunting of blood. In diastole, the flap closes, preventing left-to-right shunting.