Platypnea-Orthodeoxia Syndrome After the Bentall Procedure.

Platypnea-orthodoxia syndrome (POS) is a clinical condition that causes dyspnea and hypoxia in the sitting and standing positions. In this case, a 67-year-old man showed hypoxemia after undergoing the Bentall procedure that worsened in the standing position during rehabilitation. Contrast-enhanced computed tomography of the thorax and abdomen revealed no cause of respiratory failure. POS was suspected as the cause of the positional exacerbation of oxygen saturation. A bubble study showed a positive grade IV within three heartbeats on transthoracic echocardiography, which also confirmed an intracardiac shunt caused by a patent foramen ovale (PFO). Percutaneous PFO closure was performed, and hypoxemia was immediately resolved. Various factors were considered to cause the POS, including right heart failure, constrictive pericarditis, and postoperative adhesions, and each of these factors was discussed. POS after open-heart surgery is very rare. This is the first reported case of POS treated with a closure device following the Bentall procedure.