Intravenous thrombolysis for acute stroke

Intravenous t-PA is effective if given to appropriate patients within 3 hours of stroke onset, and its effectiveness increases even within the first 3 hours when given as soon as possible. t-PA is reasonably safe if used in a carefully defined manner that ensures close attention to blood pressure, careful patient monitoring, no use of heparin and aspirin during first 24 hours, and appropriate patient selection. It is still unclear whether a lower dose of t-PA given with 3 hours could be as effective as but safer than the currently approved intravenous dose of 0.9 mg/kg over 1 hour. The effectiveness and safety of intravenous t-PA when given beyond 3 hours after stroke onset has yet to be conclusively demonstrated. One attractive development is the potential use of imaging, such as diffusion/perfusion MRI to determine if salvageable brain remains and if t-PA should be given in patients who are beyond the 3-hour time window. The drawback to MRI is the additional time required before the start of recanalization therapy.