Thrombolytic Therapy

The door-to-needle window for thrombolytics is 30 minutes — but giving them to the wrong patient can turn a clot-busting save into a fatal bleed. Knowing the contraindications is the real test.

Thrombolytics (fibrinolytics) like alteplase (tPA), reteplase, and tenecteplase dissolve existing clots by converting plasminogen to plasmin, which breaks down fibrin. They are indicated for STEMI when PCI is unavailable or will take longer than 120 minutes from first medical contact. The target is door-to-needle time of 30 minutes or less. Benefit is greatest within the first 3 hours and diminishes progressively, with little benefit beyond 12 hours from symptom onset. Absolute contraindications you must know: active internal bleeding, history of hemorrhagic stroke (any time), ischemic stroke within 3 months, intracranial neoplasm, suspected aortic dissection, and significant head or facial trauma within 3 months. The greatest risk is hemorrhage — especially intracranial. Before administration, establish two large-bore IVs, obtain baseline coagulation studies (PT/INR, aPTT, platelets, fibrinogen), and type and crossmatch. During and after infusion, monitor for overt and occult bleeding: neurological checks every 15 minutes for 2 hours, then every 30 minutes for 6 hours. Avoid invasive procedures — no arterial sticks, no IM injections, no Foley insertion during infusion. Apply pressure to all puncture sites for at least 20 minutes. Signs the thrombolytic worked include resolution of ST elevation, relief of chest pain, and the appearance of reperfusion dysrhythmias (especially accelerated idioventricular rhythm).

Key Distinctions

Don't confuse thrombolytics (dissolve existing clots) with anticoagulants like heparin (prevent new clot formation) — they serve different roles, though heparin often follows thrombolysis. Students mix up door-to-needle (30 minutes for thrombolytics) with door-to-balloon (90 minutes for PCI). A sudden severe headache during thrombolytic infusion is intracranial hemorrhage until proven otherwise — stop the infusion immediately and notify the provider.

Clinical Pearl

If the patient can't get to a cath lab in 120 minutes, the clot-buster comes to the patient. But always screen for bleeding risk first — you can't unlyse a brain bleed.