Figure 4.

Infarct evolution after promptly reversed transient ischemia. Schematic representation of increasing durations of middle cerebral artery (MCA) intraluminal filament insertion. The instantaneous reversal of blood circulation after withdrawal of the filament results in prompt reoxygenation of the ischemic tissue and, depending on the duration of ischemia, promotes partial or even complete recovery of energy metabolism in the infarct core. After a free interval of up to 6 to 12 hours secondary delayed cell death evolves in the area of primary energy failure. Secondary delayed cell death can be alleviated by a multitude of molecular interventions throughout the interval between primary and secondary damage. The therapeutic window is, therefore, much longer than after permanent or gradually reversed vascular occlusion. However, this extension is of limited clinical relevance because promptly reversed focal ischemia is not a model of naturally occurring stroke.