Superior vena cava syndrome after cardiac surgery

Abstract

Superior vena cava (SVC) syndrome is a group of symptoms caused by obstruction of the SVC at the junction of the right atrium. This obstruction was found to be caused by either external compression or internal occlusion. It leads then to impaired venous drainage into the heart, which will in turn reduce the preload and consequently the cardiac output that might be fatal at some stage. On the flip side, it causes blood engorgement of the upper half of the body resulting in swelling and increased pressures. SVC syndrome may happen acutely in relation to cardiac surgery as a less frequent complication. It might be then caused by mechanical obstruction by a retractor, improper placement of venous cannula, thrombus formation on top of indwelling catheters or pacemaker wires, or overflow following ‘Glenn’ surgery in pediatrics. Diagnosis of the SVC syndrome should involve a high index of suspicion in the context of cardiac surgery especially that the manifestations are not classic in all cases. So, once the manifestations of the syndrome start to appear, prompt actions should be taken to confirm the diagnosis and to start treatment to avoid hemodynamic instability resulting from the dramatic decrease in preload, taking into consideration the limited time available for the collateral drainage (e.g. from azygos, hemiazygos, or internal mammary veins) to develop and bypass the obstruction. Exploring different causes of developing SVC syndrome after cardiac surgery would help early diagnosis and management, which could be lifesaving in many scenarios.