Fibrinolytic therapy dissolves blood clots that obstruct blood vessels. Its primary purpose is to restore blood flow, especially when a clot blocks supply to a vital organ. This treatment is highly time-sensitive, with effectiveness depending on rapid administration after symptom onset.
Understanding Ischemic Stroke
An ischemic stroke occurs when a blood clot blocks an artery supplying blood to the brain, depriving brain cells of oxygen and nutrients. This blockage can be a thrombotic stroke (clot forms in brain artery) or an embolic stroke (clot travels from elsewhere). Brain tissue dies quickly, making rapid treatment essential to minimize permanent neurological deficits, disability, or death.
How Fibrinolytic Therapy Works
Fibrinolytic therapy, also known as thrombolytic therapy, uses plasminogen activators to dissolve blood clots. Agents like tissue plasminogen activator (tPA), or alteplase, and tenecteplase, convert plasminogen into plasmin. Plasmin is an enzyme that breaks down fibrin, the main protein of blood clots.
Alteplase is a standard treatment for acute ischemic stroke. Tenecteplase is a modified version of alteplase with improved pharmacological properties, including a longer half-life and higher specificity for fibrin. These characteristics may allow for better clot dissolution and reduced systemic effects on the body’s clotting system.
Both alteplase and tenecteplase are administered intravenously. Once in the body, they target the fibrin within the clot, initiating its breakdown to re-establish blood flow through the blocked artery. This aims to restore blood flow to brain tissue at risk of damage.
Administering Fibrinolytic Therapy
Fibrinolytic therapy for acute ischemic stroke is highly time-dependent, with significant benefits when treatment begins as soon as possible after symptom onset. It is administered within 3 to 4.5 hours of symptom onset. This narrow window highlights the need for immediate stroke symptom recognition and rapid transport to a specialized stroke center.
Before administration, medical professionals confirm ischemic stroke via brain imaging, like a CT scan, to rule out bleeding. Intracranial hemorrhage is an absolute contraindication due to increased bleeding risk. Other contraindications include recent head trauma or stroke (within three months), recent major surgery or trauma (within 14 days), or uncontrolled high blood pressure (systolic >185 mmHg or diastolic >110 mmHg).
Patient eligibility also considers active internal bleeding, low platelet count, or current anticoagulant use that could increase bleeding risk. Administering fibrinolytic therapy involves carefully weighing potential benefits against risks. Strict selection criteria ensure the therapy is given to patients most likely to benefit and least likely to experience severe complications.
Expected Outcomes and Safety
The primary aim of fibrinolytic therapy in acute ischemic stroke is to restore blood flow to the affected brain region, limiting brain damage. Successful reperfusion improves functional outcomes, reducing long-term disability. This therapy can improve a patient’s likelihood of achieving independence after a stroke.
Despite its benefits, fibrinolytic therapy carries risks, with bleeding being the most significant concern. The most serious complication is intracerebral hemorrhage, bleeding within the brain. The risk of symptomatic intracerebral hemorrhage ranges from 2% to 8%.
Due to serious bleeding complications, patients receiving fibrinolytic therapy require careful, continuous monitoring during and after administration. This includes frequent neurological assessments and close observation of blood pressure and cardiovascular status. Prompt recognition and management of complications are important to ensure patient safety and a positive outcome.