Introduction: Intra-operative blood flow assessments during cerebral bypass would ideally assess vessel patency, downstream cerebral perfusion, and post-operative risk of complications such as hyperperfusion syndrome (HPS). Previous studies using Indocyanine Green (ICG)-based flow analyses (Flow 800, Carl Zeiss, Oberkochen, Germany) have identified multiple parameters that can track post-bypass changes in cerebral perfusion and potentially predict HPS risk, although the optimal Flow 800 parameter and anatomic location for these analyses remains unknown.
Methods: To determine the most robust parameter and anatomic location for Flow 800 assessment of post-bypass perfusion changes and HPS risk, a retrospective analysis of an IRB-approved prospective database was performed to identify patients undergoing superficial temporal artery (STA) to middle cerebral artery (MCA) bypass. Demographic and clinical information, as well as manually calculated and automated pre- and post-bypass Flow 800 data from cortical, arterial, and venous regions of interest (ROIs) was recorded and analyzed.
Results: Seven patients underwent STA-MCA bypass (4 moyamoya, 3 carotid occlusions). Average age was 48.2 ± 13.9 years (3 females, 4 males). While all parameters measured showed trends toward improvement post-bypass, only changes in arterial and venous automated Flow 800 slope (also known as blood flow index [BFI: maximum intensity/rise time]) reached significance. 0 out of 7 patients experienced symptomatic HPS despite 5 of 7 (71.4%) having an increased HPS risk based on previously published data.
Conclusions: Flow 800 can reliably identify post-bypass changes in cerebral perfusion, with automated BFI being the most robustly affected parameter. Further studies are needed to better correlate Flow 800-based changes with post-operative HPS risk.
Patient Care: Will improve the intra-operative assessment of post-bypass risk for patients with carotid ischemia.
Learning Objectives: Learn the most robust parameter and anatomic location for Flow 800 assessment of post-bypass perfusion changes and HPS risk.