Right atrial myxoma: an unusual cause of intracardiac right-to-left shunt

A case of a right-to-left intracardiac shunt caused by a right atrial myxoma is reported. Sudden hypoxaemia was the unique symptom. Measurement of Pao2 while the patient breathed pure oxygen demonstrated the presence of a shunt. Right heart catheterization showed a patent foramen ovale and a pressure gradient between the right atrium and the right ventricle, and between the right and the left atria, explaining the shunt. Cineangiography demonstrated a right atrial myxoma, which was surgically removed. This case report illustrates how a step-by-step diagnostic procedure, based on pathophysiology, may lead to such unexpected findings.