Introduction to Reperfusion
Reperfusion is the key therapeutic strategy for successful treatment of acute ischemic stroke as it is for acute myocardial infarction. Intravenous recombinant tissue plasminogen activator was approved for the treatment of acute ischemic stroke by the US Food and Drug Administration in 1996 and represented the first scientifically proven reperfusion therapy. The success of reperfusion therapy depends not only on the achievement of recanalization, but also the degree and timing of reperfusion relative to ongoing brain ischemia. Reperfusion in response to intravenous recombinant tissue plasminogen activator may be incomplete, delayed, or unsuccessful, particularly in patients with large artery occlusions such as the internal carotid artery. Like in acute myocardial infarction, the use of devices and therapeutic approaches combining multiple drugs and/or drugs and devices are the next steps currently under study to see if reperfusion can be accomplished more often and more quickly and safely. In addition, brain imaging is being tested in ongoing trials to examine whether imaging can identify those patients who stand to benefit from reperfusion, even beyond the currently approved time window of 3 hours. The goal of these various imaging approaches is to identify a physiological rather than a chronological time window. Further delineation of an effective time window for reperfusion is critical no matter what therapeutic approaches prove to be most effective.