An interesting case: bilateral superior vena cava in a patient with end stage renal disease

A left superior vena cava, which is present in 0.5% of the population, is the result of persistence of the embryonic left anterior cardinal vein and is usually considered a normal variant. We present our experience of an incidental discovery of bilateral superior vena cava during routine evaluation of suspected intra-fistula stenosis in a dialysis-dependent patient with end stage renal disease. Our images were consistent with a left-sided venous structure draining into the heart with an independent right side superior vena cava as evidenced by fluoroscopy. There was also evidence of a 60% intra-fistula stenosis. To conclude, twin superior vena cava may be present as draining vessels independent of each other or as part of a duplicate caval drainage. While cases of persistent left superior vena cava have been associated with disturbances of cardiac impulse formation and conduction no such significant associations have been found in patients with bilateral superior vena cava. However, the variant anatomy may confound efforts during central venous catheterization as well as alter flow characteristics, such that one could postulate that the anatomy may also affect the maturation of an arteriovenous fistula.