Double superior vena cava

Case contributed by Kavitha Nair
Diagnosis certain


Incidental finding on a chest CT scan done as a metastatic work-up in a newly diagnosed patient of prostate cancer.

Patient Data

Age: 70 years
Gender: Male

There is an anomalous vessel coursing inferiorly to the left of the aortic arch and anterior to the left hilum. It is in direct continuation with the confluence of the left subclavian vein and the left internal jugular vein. Superiorly, it is communicating with a normal right sided SVC via a hypoplastic left brachiocephalic vein. Inferiorly, it drains into the coronary sinus, and thus into the right atrium. Findings are consistent with double SVC due to the presence of a persistent left SVC (anatomical variant) along with a normal right SVC.

Case Discussion

Double SVC is a rare anatomical variant that results from a persistent left superior vena cava, which is due to the embryological failure of regression of the anterior cardinal vein.

The left sided SVC drains into the right atrium in 90% of cases via a dilated coronary sinus, alternative sites include the inferior vena cava, a hepatic vein and the left atrium. Atypical left SVC drainage into the left atrium results in a right to left shunt, which can cause cyanosis and has been linked in cases of septic embolism. 

A right sided SVC is seen in 82-90% of cases of double SVC. Absence of right SVC or a left SVC draining into the left atrium has been associated with increased incidence of congenital heart diseases such as ASD,VSD and TOF.

It is important to be aware of this normal variant especially during upper limb central venous catheterization on the left side.

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