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. We were able to find only nine case reports of this rare anomaly in the English literature. All prior cases demonstrated partial anomalous pulmonary venous return which was also demonstrated to be present in this case with the use of cardiac MRI. According to our literature search, this is one of the few cases to be diagnosed with cardiac MRI.