Thrombolysis is the process of dissolving a blood clot (thrombus) using pharmacological agents that activate the body’s natural clot-dissolving mechanism. The term is most commonly used for drug treatment (thrombolytic therapy), in which clot-dissolving medicines are administered intravenously to dissolve life-threatening blood clots and restore blood flow.
The main thrombolytic drugs (also called fibrinolytics or ‘clot-busters’) include alteplase (tPA), tenecteplase, and reteplase. They work by activating plasminogen, a naturally occurring protein in the blood, which converts to plasmin and breaks down the fibrin mesh holding blood clots together.
Principal clinical uses include: acute ischaemic stroke (alteplase given within 4.5 hours of symptom onset to dissolve a clot blocking a cerebral artery); STEMI (heart attack), where thrombolytics are used when primary PCI cannot be performed within the recommended timeframe; and massive pulmonary embolism causing haemodynamic instability or cardiac arrest.
The major risk of thrombolysis is serious bleeding, including potentially fatal intracranial haemorrhage (approximately 1% in stroke treatment). There are strict contraindications including recent surgery, trauma, or previous intracranial bleeding. In STEMI management, primary PCI has largely replaced thrombolysis in the UK due to superior outcomes; thrombolysis remains important where timely PCI is not accessible.
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