A 67-year-old man was scheduled for video-assited thoracoscopic resection of a mediastinal tumor under epidural and general anesthesia. During removal of the tumor about an hour 30 minutes after the start of the operation, pulseless electrical activity developed due to uncontrollable massive hemorrhage caused by laceration of the left brachiocephalic vein. After intravenous administration of epinephrine and fluid resuscitation, compatible red cell transfusion with a different ABO group and intraoperative autotransfusion were started. Hemodynamics was unstable although bleeding was stanched. Therefore, cardiopulmonary bypass (CPB) was initiated about 2.5 hours after blanching had started. As a result, bleeding from the laceration was reduced, and the laceration was repaired. The patient recovered uneventfully and had no complications. CPB should be considered for cases of uncontrollable bleeding from a central vein and should be initiated as soon as possible.