Intraoperative EC-IC Bypass Blood Flow Assessment With Indocyanine Green Angiography in Moyamoya and Non-Moyamoya Ischemic Stroke

OBJECTIVE: Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis has been used in moyamoya disease (MD) and non-moyamoya ischemic stroke (non-MD). It is important to monitor hemodynamic changes caused by bypass surgery for postoperative management. We evaluated the bypass blood flow during STA-MCA anastomosis by using indocyanine green (ICG) fluorescence angiography. METHODS: We evaluated the bypass blood flow in 13 MD and 21 non-MD patients during STA-MCA anastomosis by means of ICG angiography with injection of ICG into the anastomosed STA. The ICG perfusion area was calculated when the ICG fluorescence intensity reached maximum. We measured cortical oxygen saturation before anastomosis by means of visual light spectroscopy. RESULTS: ICG angiography demonstrated bypass blood flow from the anastomosed STA to the cortical vessels in all patients. The ICG perfusion area in MD (20.7 +/- 6.6 cm(2)) was significantly larger than that in non-MD (8.4 +/- 9.1 cm(2), P < 0.05). The cortical oxygen saturation (58.9% +/- 8.3%) in MD was significantly lower than that in non-MD (73.4% +/- 9.5%, P < 0.05). CONCLUSIONS: ICG angiography with injection of ICG into the bypass artery allowed quantitative assessment of bypass blood flow. The bypass supplies blood flow to a greater extent in MD than in non-MD during surgery. This might be caused by a larger pressure gradient between the anastomosed STA and recipient vessels in MD. These observations indicate that MD requires careful control of systemic blood pressure after surgery to avoid cerebral hyperperfusion syndrome. ICG angiography is considered useful for facilitating safe and accurate bypass surgery and providing information for postoperative management.