BACKGROUND The entanglement of multiple central venous catheters is a rare and seriouscomplication. The Swan-Ganz catheter is a responsible for various cases. METHODS A 66-year-old male patient was under general anesthesia for a coronary artery bypassgraft surgery. As he had a pre-existing Perm catheter in the right subclavian vein, a SwanGanz catheter was inserted into the left internal jugular vein. Chest radiograph after catheterplacement revealed that the Perm catheter had migrated to the left brachiocephalic vein.The surgeon attempted to reposition it manually, but postoperative radiograph showed thatit had rolled into a loop. On postoperative day 1, radiological intervention was performed tountangle the loop, which was successful. CONCLUSIONS After placing a Swan-Ganz catheter in patients with a pre-existing central venous catheter, the presence of entanglement should be assessed. In such cases, radiology-guided correction is recommended, as a blind attempt to disentangle can aggravate thecondition.