Biatrial Drainage of a Right-Sided Superior Vena Cava.

We report a case of chronic hypoxemia in a 62-year-old woman as a result of biatrial drainage of a right-sided superior vena cava. Radionuclide ventilation and perfusion imaging revealed significant increased radiotracer activity in the kidneys, bowel, and thyroid gland suggesting a right-to-left shunt which was confirmed by contrast enhanced CT of the chest. An anatomically correct right-sided SVC drained through two channels, the larger of which emptied into the roof of the left atrium and a smaller atretic portion feeding the right atrium.