A 48-year-old female with a symptomatic giant carotid cavernous aneurysm underwent endovascular treatment with multiple Pipeline Flex embolic devices (PED). The delivery catheter had to take a complicated course of multiple turns to cross the aneurysm, and its loop was tied in the aneurysm. When the catheter was to be withdrawn, it was apparent that the tied catheter had made a tight knot that bound the tail of the previous PED together. We successfully retrieved all of the system including the tied PED, and we used telescoping stents with five PEDs in the next operation. Although this is a rare complication, it is worth noting and checking to make sure that there is no knot before deploying the stent.
Keywords: aneurysm; complication; flow diverter.