A 61 year-old man presented to the Emergency Department for one day of nonspecific chest pain. Bedside echocardiogram performed by the emergency physician revealed normal systolic cardiac function but also showed a large ( > 10mm) bicornuate interatrial septal aneurysm (IASA) projecting into the right atrium (Figure 1, Video 1). There was no evidence of intraatrial thrombus. A formal echocardiogram performed later that day confirmed the diagnosis and also detected a patent foramen ovale (PFO) with a left-to-right shunt that reversed with Valsalva maneuver.