Left SVC draining to the left atrium

Case contributed by James Harvey
Diagnosis certain


Presented to the emergency department with shortness of breath. Background of multiple paragangliomas and malignant paraganglioma metastases. Referred for CTPA.

Patient Data

Age: 60 years
Gender: Female

The cardiothoracic ratio is increased without other features of pulmonary congestion/fluid overload.

Prominence of the right heart border.

Non-diagnostic CTPA due to contrast passing from the IV cannula within the left arm through the left subclavian vein to the left superior vena cava. The left SVC drains into the left atrium.

There is communication between the left and right SVCs via a small vein anterior to the aorta (left brachiocephalic vein). The pulmonary trunk is non-opacified.

Arterial enhancing lesions adjacent to the left common carotid artery and within the body of the left adrenal gland represent known paragangliomas. There are also arterially-enhancing liver metastases.


Repeat CTPA


Diagnostic study following right-sided contrast injection. No PE.

Contrast within the left renal pelvis and gallbladder relates to the prior study.

Case Discussion

SVC duplication is a relatively common congenital variant diagnosed incidentally. A left-sided SVC is rarely seen in isolation, usually it is accompanied by the right sided SVC - as in this case.

The left IVC more commonly drains to the coronary sinus. Drainage to the left atrium results in a right-to-left shunt which is unlikely to be symptomatic.

It is helpful for clinicians to be aware of the variant prior to pacing lead or central venous line insertion.

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