Thrombolysis is a medication-based treatment that dissolves the clot blocking a brain artery in acute ischemic stroke. The intravenous "tissue plasminogen activator" (tPA / alteplase) breaks down fibrin and restores blood flow. Once deprived of oxygen, brain cells begin to die within minutes; thrombolysis halts or reverses this loss.
The therapeutic window is critical. Classically given within the first 4.5 hours, in selected patients it can be extended up to 9 hours, guided by advanced imaging (perfusion–diffusion mismatch). Before starting, CT or MRI is performed to rule out hemorrhage.
Thrombolysis is life- and function-saving but is not for every patient. Recent major surgery, active bleeding, severe uncontrolled hypertension, head trauma in the past three months, and elevated INR are among the principal exclusion criteria. Patient selection is made within minutes at experienced stroke centers.