Absent right superior vena cava with hypoplastic proximal inferior vena cava.

We describe the precise preoperative diagnosis of a very rare anomaly that comprises absence of the right superior vena cava, persistence of the left superior vena cava, and proximal hypoplasia of the inferior vena cava draining into the left superior vena cava via the hemiazygos vein associated with a large atrial septal defect and tricuspid regurgitation.