Presentation
Patient with suspected pulmonary embolism.
Patient Data
It's possible to identify an obstructed superior vena cava with chronic thrombosis. There is an exuberant collateral venous circulation on thorax characterized by: Dilated azygos vein, dilated pericardial veins, dilated anterior thoracic vein and other smaller mediastinal veins that drain to left renal vein and inferior vena cava.
There is also left pleural effusion.
No signs of pulmonary embolism.
Case Discussion
The brachiocephalic veins, superior vena cava and azygos-hemiazygos system drain the upper extremities and the head and neck. They are connected by a rich network of smaller venous plexuses that are normally not or only barely opacified on chest CT. On superior vena cava thrombosis the blood flow diverts into this network of collateral channels.
The development of rich collaterals protect this patient against developing the most severe symptoms of superior vena cava syndrome.