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.
LA: left atrium; RA: right atrium.
Courtesy of Thomas Binder, MD. University of Vienna.
