Introduction: Indocyanine green (ICG) videoangiography has been previously established as a non-invasive technique to gauge patency of a bypass graft. However, altered flow through the bypass graft may directly cause delayed graft occlusion. Here we report on 3 types of flow that were observed through cerebrovascular revascularization procedures.

Methods: Thirty-two patients who received EC-IC or IC-IC bypass for ischemic stroke (13 patients), moya-moya disease (9 patients), complex aneurysms (10 patients, 6 giant aneurysms, 2 carotid blister-like and 2 dissecting PICA), were retrospectively analyzed. A total of 35 bypasses were performed including 25 STA-MCA (3 bilateral), 6 EC-IC vein grafts, 1 EC-IC radial artery graft, 1 PICA-PICA, 1 MCA-PCA, and 1 OA-PICA grafts. All patients were evaluated with intraoperative ICG, and all had postoperative CTA or angiograms within 24-72 hours of surgery.

Results: Robust anterograde flow (Type I) was noted in 30 grafts (86%). Delayed but patent graft enhancement and anterograde flow (type II) was observed in 4 cases (11%). There was one Type III graft in which flow was not continuous to the bypass site. Postoperative imaging revealed 5 occluded grafts (17%); all of them were Type II or III on videoangiography. All Type I grafts were patent on postoperative imaging. The 5 patients with Type II or III grafts were evaluated by flow probe and re-exploration of the bypass site; in all cases the reason was felt to be the recipient vessel competitive flow. In no case there was stenosis or technical issue at site of anastomosis.

Conclusions: ICG videoangiography is reliable for evaluating the flow through the EC-IC or IC-IC bypass. The type of flow observed through the graft has a direct relationship with postoperative imaging findings. Despite the possibility of competitive flow, Type III and some Type II flow through the graft indicate the need for graft evaluation and anastomosis exploration.

Patient Care: Use of ICG-videoangiography is a non-invasive, safe method to characterize EC-IC bypass flow, and can be implemented to establish correlation between a bypass graft flow and patient outcomes

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of characterization of bypass graft flow using ICG videoangiography , 2) Discuss, in small groups, relationship between type II and III graft flow and postoperative patency of the bypass graft, 3) Identify an effective treatment protocol where ICG videoangiography can be helpful in predicting patency of postoperative bypass graft.

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