Obstructions of the upper venous system may be due to spontaneous thrombosis or the presence of hemodialysis or chemotherapy catheters, or even the presence of extrinsic compression due to intra-thoracic tumors. The use of endoprosthesis for the treatment of these obstructions has become common practice, and its indications include situations of risk for pulmonary embolism, superior vena cava syndrome, and loss of vascular access. Within this context, the use of intracardiac ultrasound may be useful in evaluating the extension and severity of the obstructive lesion, besides providing important information about the mural and intraluminal morphology of the venous system. The authors report the case of a patient with superior vena cava syndrome caused by thrombosis at the entry pathway of the right atrium, besides discussing the subject by means of literature review.