Superior Vena Cava Syndrome During Femoro-Femoral Veno-Venous Extracorporeal Membrane Oxygenation: A Case Report.

Superior vena cava (SVC) syndrome is a clinical condition caused by an obstruction of blood flow through the SVC, which may complicate veno-venous extracorporeal membrane oxygenation (V-V ECMO). We report a case occurring early after initiation of femoro-femoral V-V ECMO in a 69 year old patient with severe acute respiratory distress syndrome (ARDS). Clinical presentation included facial and upper body edema, markedly elevated central venous pressure, and high-pressure alarms on all infusion pumps. Computed tomography demonstrated retrograde flow from a reinfusion cannula positioned in the right atrium toward the SVC, causing functional obstruction of venous return without anatomical stenosis. Cannula repositioning led to rapid resolution of symptoms and hemodynamic improvement. This case highlights key technical considerations in femoro-femoral V-V ECMO: reinfusion cannula tip position must avoid directed flow toward the SVC, particularly when distal segments are non-radiopaque; cannula length and diameter significantly influence reinfusion pressure; and indirect signs such as elevated central venous pressure and infusion pump alarms may facilitate early diagnosis. Optimization of cannula selection and positioning is essential to prevent this rare but severe complication.