Detecting a patent foramen ovale (PFO) with TEE

Midesophageal bicaval view in a patient with a PFO. The PFO was detected with Doppler color-flow imaging (panel A) showing blood flow from the LA into the RA at the fossa ovalis, where the septum secundum and septum primum have failed to fuse completely (arrow). The PFO was additionally verified by agitated saline contrast injection into the RA (panel B) that demonstrated transit of echo contrast from the RA into the LA (double arrow) through the PFO. Maintaining positive airway pressure for a short period of time and acutely releasing the airway pressure during the injection of echocontrast into the RA transiently increases the RA pressure in relation to the LA pressure to improve the likelihood of detecting a PFO using TEE.