Abstract: Two patients are presented with right atrial tumors, who were considered to be at risk for tumor thrombus migration down the venous line into the cardiopulmonary bypass (CPB) circuit during surgical excision, which may lead to compromised or interrupted venous drainage. An arterial line filter was placed in the venous line to capture any material that might become dislodged and embolize into the circuit. Vacuum-assisted venous drainage, at approximately -50 mmHg, was used to overcome any resistance caused by the filter in the venous line. In one case, tumor thrombus obstructed the filter, requiring the use of the bypass line around the filter, so venous return could be maintained. In both cases, thrombus was found in the filter. The first case was a 44-year-old female (81 kg, 137 cm, body surface area (BSA) 1.66 m2) who presented with a metastatic pheochromocytoma with associated thrombus arising from the left adrenal gland and extending into the inferior vena cava (IVC) and right atrium. The second case was a 37-year-old male (95 kg, 178 cm, BSA 2.17 m2), who presented with a very large angiosarcoma tumor involving almost the entire right atrium. We have shown that venous line filtration with vacuum-assisted venous drainage can be performed safely, and should be considered in cases where there is tumor thrombus in the vena cava or right atrium, which may threaten venous return.