Superior vena cava syndrome

This is obstruction to the superior vena cava ( SVC ) blood flow by external compression , thrombosis or direct invasion of SVC ( Scottish Palliative Care Guidelines )SVC syndrome ( SVCS ) is the term used to describe the collection of clinical signs and symptoms that result due to a partial or complete obstruction of blood flow through the SVC

SVC is a thin walled compliant vessel formed by the junction of the left and right innominate ( brachiocephalic veins ) SVC transports blood from the head and neck , upper extremities and parts of chest wall towards the heart SVC accounts for about 1/3rd of the total venous return to the heart When SVC is obstructed - blood starts to flow via multiple small collaterals to the azygous vein or the inferior vena cava ( the largest one is via the azygous -hemizygous vein which consists of azygous vein , hemizygous , intercostal , lumbar veins ) As SVC has thin wall and low venous pressure - it is amongst the first of the mediastinal structures to be obstructed Intracranial venous pressure which is normally maintained between 2 to 8 mm Hg may rise up to 40 mm...