Tricuspid regurgitation causing a right to left interatrial shunt with normal pulmonary pressures

We describe a patient who presented with asymptomatic hypoxia refractory to supplemental oxygen. Transthoracic echocardiography and angiography demonstrated a tricuspid valve with a large regurgitant jet oriented directly at a patent foramen ovale, producing a right to left shunt with systemic hypoxia. The patient was found to have normal right-sided cardiac pressures as well as normal pulmonary arterial pressures, demonstrating the shunt was secondary to the tricuspid regurgitant jet and not a result of a pressure gradient between atria. Surgical correction of the tricuspid valve and closure of the patent foramen ovale resulted in resolution of the patient's hypoxemia.