The superior vena cava (SVC) is the large vein that returns deoxygenated blood from the head, neck, arms, and upper chest to the right atrium of the heart. It is formed by the junction of the two brachiocephalic veins and descends into the right atrium. Together with the inferior vena cava (which collects blood from the lower body), it forms the main venous inflow to the right side of the heart.
In critical care and interventional cardiology, the SVC has important practical significance. The tip of a central venous catheter (CVC) inserted via the internal jugular or subclavian vein is ideally positioned at the SVC-right atrium junction, allowing measurement of central venous pressure and safe delivery of potent vasoactive medications. Following cardiac arrest, central venous access is typically placed rapidly as part of intensive care admission to support vasopressor delivery and monitoring.
SVC syndrome is a condition in which the SVC is obstructed, causing facial and upper limb swelling, headache, and engorgement of veins on the neck and chest. The most common cause is compression by a lung cancer or lymphoma. Thrombosis of the SVC can also occur as a complication of central venous catheters or pacemaker/ICD leads.
In ICD and pacemaker implantation, device leads are passed through the subclavian or cephalic vein into the SVC and then into the right atrium and right ventricle. The SVC is therefore directly involved in the implant pathway for all transvenous cardiac devices.
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