Air vent of vein graft in extracranial-intracranial bypass surgery.

Revascularization with a vein graft is a mandatory method for treatment of dissecting or pseudoaneurysms of the internal carotid artery. We report the necessity for an air vent from the vein graft and explain its use in our two cases. In Case 1, we searched for a great saphenous vein around its junction with a femoral vein during the harvest of vein graft. An accessory branch of that great saphenous vein was also found around the junctional region with a femoral vein, and was temporarily ligated. At first, anastomosis was completed on both the distal and proximal sides. After the proximal side of a vein graft was opened and the ligation of the branch was loosened, an air vent could be made through the branch of the vein graft. Multiple air bubbles and a large quantity of white microemboli were discharged through this branch. The postoperative course was uneventful. In Case 2, the air vent was omitted to shorten ischemia. During the opening of the vein graft, the migrated air was observed to move to the middle cerebral artery. A computed tomography scan demonstrated that brain infarction and dysarthria occurred postoperatively. The air vent of the vein graft is essential in extracranial-intracranial bypass surgery, because the air bubbles or microthrombi are easily trapped around the valve and cause cerebral infarction. An air vent can be easily made if the branch of a vein graft exists in the outflow pathway, because intraluminal air or thrombus can be washed out through the branch at the final stage of surgery.