Clear demonstration of platypneaorthodeoxia syndrome during transesophageal echocardiography

An 86-year-old male patient visited a cardiology outpatient clinic with dyspnea, which was prominent on standing. His blood pressure was 138/76 mm Hg and heart rate was 96/bpm. Pulse-oximeter revealed an oxygen saturation (SpO2 ) level of 98% in supine position; however, it decreased to 82% in the sitting position (Fig. 1a). The patient was examined for the differential diagnosis of the platypnea-orthodeoxia syndrome (POS). We performed transthoracic echocardiography (TTE), and contrast transition from the right atrium (RA) to the left atrium (LA) was observed in the sitting position (Video 1). Transesophageal echocardiography (TEE) was performed to obtain a detailed visualization of interatrial septum (IAS). Patent foramen ovale (PFO) tunnel was observed in TEE and a color Doppler imaging performed revealed a transition from LA to RA in the supine position (Fig. 2a, 2b). Contrast injection from right upper extremity vein was performed, and no transition was observed in the supine position (Fig. 2c, Video 2). Thereafter, the patient was instructed to be in the sitting position while performing TEE, and an opening of PFO tunnel was detected (Fig. 2d, Video 3). Contrast transition from RA to LA was observed in the sitting position (Fig. 2e, Video 4).