Therapeutic time window for YAG laser-induced reperfusion of thrombotic stroke in hypertensive rats.

We examined the novel YAG laser-induced reperfusion method in the photothrombotic middle cerebral artery (MCA) occlusion model in spontaneously hypertensive rats. In the 1 h ischemia group, infarct volume was significantly reduced to 41.1 +/- 15.6 mm3 compared with 81.6 +/- 18.3 mm3 in the no-reperfusion group. There were no significant differences in infarct volume among 2 h or 3 h ischemia and no-reperfusion groups. Three of six rats in the 3 h ischemia group showed hemorrhagic infarction. Our present results showed that recirculation must be instituted within 2 h of MCA occlusion to get beneficial effects in our model, supporting the concept of a narrow therapeutic time window for intervention in ischemic stroke.