Impact of catheter configuration and proximal blood flow control on intra-arterial cooling for ischemic stroke: an experimental and modeling study

BACKGROUND: As endovascular thrombectomy has become the standard of care for patients with large-vessel occlusion stroke, interest in intra-arterial (IA) selective brain cooling as a method of delivering therapeutic hypothermia has emerged. However, the impact of catheter configuration and competing warm blood flow on IA cooling efficiency is not well understood. METHODS: We constructed a closed-loop circulatory system to perform in vitro experiments of IA cooling and tested the impact of seven catheter configurations on cooling efficiency, including single and co-axial catheter setups, non-insulated and insulated catheters, and proximal blood flow control (using balloon guide catheter (BGC) inflation) versus no flow control. Thermal modeling was performed to assess the relationship between catheter and internal carotid artery (ICA) flow rates and predicted brain temperature. RESULTS: After 10 min of delivering chilled infusate, the least effective cooling configuration was administering coolant directly through a non-inflated BGC, achieving a 1.2°C reduction in predicted brain temperature. The most effective cooling configuration was the co-axial combination of an insulated catheter and a fully inflated BGC, achieving a 7.8°C reduction in predicted brain temperature. Without proximal blood flow control (BGC inflation), high catheter flow rates were required to overcome rewarming from native ICA flow. CONCLUSIONS: These findings emphasize the impacts of catheter flow rate, catheter insulation, and competing warm blood flow on cooling efficiency.