An Uncommon Case of Superior Vena Cava Syndrome Following Cardiac Surgery

Abstract Superior vena cava (SVC) syndrome (SVCS) is due to the obstruction of the SVC leading to swelling of the upper body and to low cardiac output. Non tumoral causes, mainly thrombosis of endovascular devices, account for 30% of cases. We report a case of acute iatrogenic SVCS. A 7 years old 16 kg boy underwent mitral valve surgery in severe rheumatic mitral regurgitation. After induction a 15 cm 5.5 Fr 3 lumens central venous catheter (CVC) was inserted in the right internal jugular vein (IJV) under ultrasound guidance without issues. After achieving proper anticoagulation ascending aorta (18 Fr) and bicaval cannulation were performed (20 Fr single stage cannula with right–angled metal tip in the SVC and 26 Fr single stage cannula in the inferior vena cava). Cardiopulmonary bypass (CPB) was performed with pediatric circuit and the mitral valve was repaired. Despite apparently good result of the repair and uneventful weaning from CPB a more accurate transesophageal echo (TEE) showed moderate iatrogenic mitral stenosis. Cannulation was re–performed with same size cannulas and mitral valve replacement (St.Jude 25 mm) was provided. After weaning from CPB with mild cardiovascular support (adrenaline 0.03 mcg/kg/min and noradrenaline 0.05 mcg/kg/min) the TEE showed no abnormalities and the patient was transferred to the ICU in stable conditions. The central venous pressure (CVP) never raised over 10 mmHg. In the ICU the patient developed sinus tachicardia and hypotension, unresponsive to fluids and vasopressors, and swelling of the face with no increase in CVP. The chest Xray showed enlargement of the right upper mediastinum with TEE evidence of accellerated flow in the SVC around the CVC (fig.1). The patient was taken to the operating room and a too tigh pursue string suture was found on the SVC. After optimization of the suture the flow through the SVC was restored with immediate clinical improvement and de–escalation of the cardiovascular support. The face oedema quickly decreased allowing extubation on the day after surgery. The following course was uneventful. SVCS is a life threatening complication of cardiac surgery. A too tight pledgetted pursue–string suture is an uncommon cause compared to clot compression. The CVP measured by a IJV CVC is generally elevated in SVCS, but in our case the tip of the CVC was downstream to the stenosis so showing normal values. Multimodal monitoring is mandatory to lead to emergency surgical treatment in case of need.