Detection of Right to Left Shunt by Transesophageal Echocardiography in a Patient with Postoperative Hypoxemia

Intracardiac right to left shunt through a patent foramen ovale (PFO) may result in the development of hypoxemia after cardiac surgery. Cardiac tamponade and mechanical ventilation with high positive end-expiratory pressure are the most common factors responsible for enhancing intracardiac right to left shunt through a PFO. We report an 83-year-old woman with Stanford type A dissecting aneurysm who developed hypoxemia and paradoxical air embolism after reconstruction of ascending aorta and Bental's procedure. Transesophageal echocardiography (TEE) revealed right to left shunting via a PFO. Surgical closure of the PFO was done without delay. This case illustrates the role of TEE in prompt diagnosis of intracardiac right to left shunting through a PFO causing postoperative hypoxemia after cardiac surgery.