Acute right to left shunt-Combination of tricuspid valve endocarditis, Chiari network, and ostium secundum atrial septal defect.

A 72-year-old Tongan female was admitted to our facility with dyspnea and refractory hypoxia. She became febrile and blood cultures were positive for Enterococcus faecalis. Transesophageal echocardiography was performed showing two large vegetations on the tricuspid valve causing severe regurgitation. The tricuspid regurgitant jet with the assistance of a large Chiari network was being directed across an ostium secundum atrial septal defect. This clinical scenario represented an unusual cause of acute right to left shunt explaining the patient's refractory hypoxia. <Learning objective: Acute right to left intra-cardiac shunts occur rarely however should be considered in any patient with acute onset refractory hypoxia.>.