Acute Ischaemic Stroke Thrombolysis and Thrombectomy
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Direct answer
Acute ischaemic stroke is treated within defined time windows, with intravenous alteplase or tenecteplase given within 4.5 hours of the last known well time. Mechanical thrombectomy is offered for large vessel occlusion within 6 hours, and up to 24 hours in selected patients chosen by imaging. Non-contrast CT of the head is done first to exclude haemorrhage, and eligibility then depends on blood pressure, coagulation status and bleeding risk.
What you must remember
- Last known well: the clock starts when the patient was last seen normal, not when the deficit was discovered.
- Alteplase dose: 0.9 mg per kg, maximum 90 mg, with 10 per cent as an initial bolus and the rest infused over 60 minutes.
- Tenecteplase dose: 0.25 mg per kg as a single bolus, maximum 25 mg, is an accepted alternative.
- Key contraindications: intracranial haemorrhage, major trauma or surgery, gastrointestinal bleeding within 21 days, platelets below 100,000 per microlitre and INR above 1.7.
- Anticoagulants: a direct oral anticoagulant within 48 hours excludes thrombolysis unless the coagulation tests are normal.
- Blood pressure: it must be below 185/110 mmHg before thrombolysis, achieved with labetalol or nicardipine if needed.
- Thrombectomy target: occlusion of the internal carotid or proximal middle cerebral artery, usually with an early CT score of about 6 or more.
- Adverse effects: symptomatic intracranial haemorrhage, and angioedema, which is more likely in patients taking an ACE inhibitor.
The first hour of treatment, step by step
The decision is a sequence of gates, and each gate must be cleared before the next. The steps below assume a patient with a confirmed focal deficit at the door.
- Record the time: note the last known well time, because it sets the treatment window and the door-to-needle target of 60 minutes.
- Check glucose: hypoglycaemia is an important mimic, and it is corrected before the stroke pathway continues.
- Image immediately: non-contrast CT excludes haemorrhage, since thrombolysing a bleed is the catastrophic error.
- Run the contraindications: check platelets, INR, recent surgery or trauma, gastrointestinal bleeding and anticoagulant use before any drug is given.
- Control blood pressure and give the drug: lower pressure below 185/110 mmHg, then give alteplase or tenecteplase within the window.
- Decide on thrombectomy: CT angiography showing proximal occlusion brings the patient to thrombectomy, given after thrombolysis when eligible.
- Start stroke-unit care: swallow assessment, euglycaemia, DVT prophylaxis and early rehabilitation, with aspirin deferred for 24 hours after thrombolysis.
Where the exam tries to catch you
The stem gives times and numbers, and the trap is a single swapped figure that changes the decision.
- Trap: starting the 4.5 hour clock from the time symptoms were discovered Correct: the clock starts at the last known well time, so a patient found on waking is judged from when they were last normal.
- Trap: giving alteplase to a patient on a DOAC within 48 hours Correct: this is a contraindication unless coagulation tests are normal.
- Trap: delaying thrombectomy because thrombolysis was given Correct: thrombectomy follows thrombolysis when eligible, and it should not be delayed for it.
- Trap: leaving blood pressure at 200/110 before alteplase Correct: lower it below 185/110 first with labetalol or nicardipine, then thrombolyse.
Frequently asked questions
What is the time window for intravenous alteplase in acute ischaemic stroke?
Intravenous alteplase is given within 4.5 hours of the last known well time in acute ischaemic stroke. Tenecteplase is an accepted alternative within the same window, and the time is measured from when the patient was last normal.
Which blood pressure threshold must be met before thrombolysis?
Blood pressure must be below 185/110 mmHg before thrombolysis, and it is maintained below 180/105 mmHg for the first 24 hours after treatment. Labetalol or nicardipine is used to lower it when it is above the threshold.
When is mechanical thrombectomy considered beyond 6 hours?
Thrombectomy is considered beyond 6 hours, up to 24 hours, in selected patients with large vessel occlusion and salvageable brain tissue on imaging. Clinical-core mismatch (DAWN) or perfusion imaging mismatch (DEFUSE-3) on CT or MRI is used to choose these patients.
Which brain imaging is needed before thrombolysis?
Non-contrast CT of the head is needed before thrombolysis to exclude intracranial haemorrhage. It is the first investigation in every acute stroke, and CT angiography is added to find a large vessel occlusion.