Superior vena cava stents: Doppler US of the internal mammary veins to detect collateral flow--preliminary observations.

In 12 patients with superior vena cava syndrome secondary to malignant disease, duplex Doppler ultrasound (US) was performed in the internal mammary veins. In all patients, flow was retrograde. After stent placement, flow direction was again antegrade on one side (17%) or both sides (83%). During follow-up in the internal mammary veins, blood flow remained unchanged in 10 patients and retrograde flow recurred in two patients at 2 and 5 months, respectively. In these two patients, helical computed tomography showed stent failure. Successful treatment in one patient normalized the direction of flow in the internal mammary vein. Doppler US in the internal mammary veins allowed accurate evaluation of function of superior vena cava stents.