The effect of a microcatheter-based selective intra-arterial hypothermia on hemodynamic changes following transient cerebral ischemia

OBJECTIVES: We investigated the effect of a microcatheter-based selectively induced intra-arterial hypothermia on hemodynamic changes following transient cerebral ischemia in rats. METHODS: Stroke was induced in male Sprague-Dawley rats by a two-hour middle cerebral artery occlusion (MCAO) using a microcatheter. After the two-hour MCAO, 0·9% cold saline (0°C) was selectively infused through a microcatheter. Cerebral blood flow (CBF) in the ischemic brain region was continuously monitored by Laser-Doppler flowmetry (LDF) during the procedure. Following ischemia/reperfusion, serial functional neurologic testing was performed, and cerebral infarct volume was evaluated after 48 hours. RESULTS: The local cold saline infusion, via a microcatheter, achieved a rapid induction of brain hypothermia (cerebral cortex from 37·1 ± 0·3 to 30·7 ± 0·4°C; striatum from 37·5 ± 0·3 to 30·9 ± 0·5°C). When compared to the non-treatment group, the local cold saline infusion treatment reduced both post-ischemic hyperperfusion (about 40%, P < 0·01) and delayed post-ischemic hypoperfusion (P < 0·01), improved functional neurological testing (P < 0·01), and reduced both cerebral infarction volume (40·6 ± 5·3 vs. 61·7 ± 8·6%, P < 0·01) and cerebral edema (7·8 ± 2·6 vs.15·4 ± 3·2%, P < 0·01). CONCLUSION: Cold saline, when infused directly into the ischemic brain region, can confer robust neuroprotection by reducing immediate post-ischemic hyperperfusion and delayed post-ischemic hypoperfusion.