1. Therapeutic hypothermia is a powerful neuroprotective method for the treatment and prevention of cerebral ischemia. With the challenges of current systemic cooling concepts, however, it would be desirable to have a system that is practical, is easily integrated into the work-flow and allows to cool the organ or tissue of interest quickly, selectively and safely with accurate maintenance of selective cooling. Using a novel intra-arterial catheter system we investigated the speed, feasibility and safety of selective brain cooling in swine cerebrovascular models. Secondly, the ability of the controller to accurately maintain the infusate temperature at target temperature was determined in a bench model. In 13 Yorkshire pigs (37-55kg), under general anesthesia, with mechanical ventilation, monitoring of vitals, vascular access, and bilateral intracranial (frontal lobes) temperature probes (Raumedic, GmbH, Germany), we performed unilateral coil embolization of the external carotid artery (ECA) in order to create a carotid artery system more similar to that in humans (Figure 1). Improved brain perfusion (“internalized” as in humans) was confirmed with ipsilateral intra-carotid bolus injections of equal amounts of cold saline before and after embolization under monitoring of transient drops in brain temperature (before vs. after: 0.22±0.12°C vs. 0.66±0.50°C)[1]. Data from 9 pigs were analyzed. The median time to reach target brain temperature of 33⁰C was 5 minutes (IQR 3.7–10.6min), brain temperature (baseline 37.3±0.9⁰C) dropped by 3.6⁰C (95%-confidence interval 2.3-4.9⁰C) in 10 minutes and by 3.8⁰C (95%-CI 2.9-4.8⁰C) in 15 minutes (Figure 2). Selective and accurate maintenance of cooling at target temperature was achieved over 2 hours (average 32.5±1.6⁰C). The decrease in temperature of the infused brain hemisphere was significantly lower than the temperatures of the contralateral hemisphere or the body (esophageal/rectal) which continued over the duration of the study. Total volume input and output were 3.3±1.3L and 1.1±0.7L, respectively. Hematocrit decreased slightly from 26.1±2.5% at baseline to 24.2±2.8% (p=0.045). Gross- and histopathological evaluation of the organ specimens revealed no signs for ischemic or traumatic injury due to the cooling procedure. The results of the vascular bench model experiment demonstrate that, despite the wide variation of simulated ICA blood flow (nvFR: 80 - 250ml/min) at 37°C, the control algorithm quickly achieves target arterial input temperature of 33°C and maintains it accurately at an average 32.95±0.36°C (Figure 3). Selective brain cooling and maintenance of selective cooling is feasible and safe with intra-arterial infusion of cold fluids in pigs. Brain cooling is achieved rapidly and can be maintained accurately with the Hybernia Catheter System. This selective cooling technology may provide safe and rapid organ protection in acute clinical settings (coronary disease, ischemic stroke) as an adjunct during endovascular recanalization procedures, as well as in elective procedures of the carotid (CAS) or coronary vessels (PCI). Synergy with existing systemic hypothermia devices may be achieved with a bridging protocol to long-term hypothermia Brain Cooling with a Novel Endovascular Catheter J.H. Choi 1,2, S. Mangla 3, F.C. Barone 1, C. Novotney 4, J. Pile-Spellman 2,5 State University of New York Downstate Medical Center, Department of Neurology 1, Interventional Neuroradiology 3, Comparative Medicine 4, Brooklyn, NY, USA, Neurological Surgery P.C., Lake Success, NY, USA 5 ; Hybernia Medical, LLC, NY, USA 2 Introduction & Objectives Methods The endovascular catheter is a 4.5 French thermally insulated infusion-type catheter with embedded temperature sensors (Hybernia Medical, LLC). The external pump-cooling system infuses cold physiological fluid through the catheter in an algorithm-controlled fashion with continuous data input from the embedded sensors. The catheter was navigated to the ipsilateral common carotid artery (CCA) under fluoroscopic guidance. Cold normal saline (0-4°C) was then infused at flow-rates between 0.1-70.0ml/min for up to 2 hours with a target brain temperature of 33°C. Blood samples were taken in regular intervals. The swine experiment was performed under manual control of cold infusion flow rates. The vascular bench experiment, performed after completion of the hardware controller, was done in an automated feedback-controlled environment. After completion of the selective brain cooling procedure and a brief rewarming period, the pig was euthanized and the carotid artery, brain and several other organs were extracted for pathological examination (trauma and ischemic injury). Figure 1. Cerebral angiogram in a representative animal after injection of contrast into the right CCA before (A) and after (B) embolization of ECA branches. This study was supported by a grant, NIH-NINDS STTR R41-NS067964. Hybernia Medical, LLC Results Figure 2. Brain temperature over 120 minutes of selective endovascular brain cooling with the Hybernia Catheter. Mean values and 95% confidence intervals (vertical lines). Figure 3. Controller test on vascular bench model with simulated blood circulation. T1 enlarged nvFR= native vessel flow rate of the ICA at 37°C T1= infusate temp [ml/min] left Y- axis Conclusion References 1. Mangla S, Choi JH, Barone FC, et al. Endovascular external carotid artery occlusion for brain selective targeting: A cerebrovascular swine model. BMC Research Notes 2015; doi: 10.1186/s13104-015-1714-7.