What are the guidelines for intravenous thrombolysis for acute ischemic stroke?

Intravenous thrombolysis (IVT) with fibrinolytic drugs can significantly improve functional outcomes for patients with acute ischemic stroke. A definitive understanding of what are the guidelines for intravenous thrombolysis for acute ischemic stroke? is essential for timely, life-saving treatment in medical practice.

Quick Summary

A summary of the current guidelines for IV thrombolysis for acute ischemic stroke, including patient selection criteria, therapeutic time windows, drug administration protocols for alteplase and tenecteplase, and post-procedure monitoring. The process emphasizes rapid evaluation, strict adherence to protocols, and aggressive blood pressure management to minimize risks.

Key Points

• Time is Brain: IVT effectiveness is highly time-dependent, with earlier treatment offering a greater chance of a favorable outcome.

• Standard Time Window: IVT is typically recommended within 4.5 hours of symptom onset for eligible, unselected patients.

• Extended Time Window: In specific cases, advanced imaging can extend the treatment window up to 9 hours or longer, including for 'wake-up strokes'.

• Drug Options: Both alteplase and tenecteplase are recommended, with tenecteplase often preferred for its single-bolus convenience, particularly when endovascular therapy is planned.

• Strict Screening: Rigorous patient evaluation, including blood pressure and brain imaging, is necessary to rule out contraindications like hemorrhage before treatment.

• Continuous Monitoring: Close neurological assessment and blood pressure control are required for at least 24 hours after treatment to manage the risk of complications, especially intracranial hemorrhage.

• Multidisciplinary Approach: Effective IVT requires rapid coordination among emergency medical services, neurology, and radiology teams.

Intravenous Thrombolysis for Acute Ischemic Stroke

Intravenous thrombolysis (IVT) uses clot-dissolving drugs to restore blood flow to the brain after an acute ischemic stroke. Because its effectiveness depends heavily on prompt administration, understanding what are the guidelines for intravenous thrombolysis for acute ischemic stroke? is essential. Major guidelines from organizations such as the American Heart Association (AHA), American Stroke Association (ASA), and European Stroke Organisation (ESO) provide a framework for treatment, emphasizing rapid evaluation, strict adherence to protocols, and monitoring to maximize benefits and minimize risks.

Patient Selection: Inclusion and Exclusion Criteria

Careful selection is vital to balance the benefits of reperfusion with the risk of complications, particularly intracranial hemorrhage. Assessment must be quick and thorough.

Key Inclusion Criteria

• Diagnosis of acute ischemic stroke with a measurable neurological deficit.
• Age 18 years or older (with some exceptions).
• Symptom onset within 4.5 hours for most patients. Later windows may be possible with advanced imaging.
• No hemorrhage or significant early ischemic changes on head CT (e.g., ASPECTS ≥7).
• Controllable blood pressure below 185/110 mmHg before treatment and below 180/105 mmHg during and for 24 hours after.

Key Exclusion Criteria

• Intracranial hemorrhage seen on CT.
• History of intracranial hemorrhage, stroke, or severe head trauma in the past 3 months.
• Major surgery within the last 14 days.
• Active internal bleeding or symptoms of subarachnoid hemorrhage.
• Known intracranial abnormalities like neoplasms or aneurysms.
• Platelet count below 100,000/mm³.
• Use of oral anticoagulants or elevated INR/aPTT.
• Blood glucose below 50 mg/dL.
• Minor or rapidly improving symptoms considered non-disabling.

Medications and Administration Protocols

Alteplase and tenecteplase are the primary thrombolytic agents. Guidelines determine the choice and administration.

Feature	Alteplase (Activase)	Tenecteplase (TNK-tPA)
Mechanism	Recombinant tPA, activates plasminogen at the clot site.	Modified tPA, higher fibrin specificity, longer half-life.
Administration	Bolus followed by infusion over 60 minutes.	Single IV bolus over 5-10 seconds.
Standard Use	Was the standard within the 4.5-hour window.	Increasingly preferred within the <4.5 hour window, especially if mechanical thrombectomy is considered.
Convenience	Less convenient due to infusion time, can complicate transfers.	Single bolus simplifies administration and transfers.

Post-Thrombolysis Care and Monitoring

Patients require close monitoring for at least 24 hours after IVT to detect and manage complications.

• Monitoring: Patients should be in a stroke unit or ICU.
• Blood Pressure: Maintain BP below 180/105 mmHg for 24 hours, with frequent checks. Avoid excessive drops.
• Neurological Assessment: Regular checks using NIHSS.
• Emergency Response: If neurological status worsens, stop the infusion and get an emergency CT.
• Procedures: Avoid non-essential invasive procedures for 24 hours.
• Medications: Delay antiplatelets/anticoagulants for 24 hours; use mechanical DVT prophylaxis.

Common Complications and Considerations

The main risk is symptomatic intracranial hemorrhage (sICH), occurring in a small percentage of patients. Other risks include angioedema and systemic bleeding. Factors increasing sICH risk include older age, higher stroke severity, high blood glucose, and uncontrolled hypertension.

Conclusion

Following guidelines for intravenous thrombolysis in acute ischemic stroke is crucial for positive outcomes. The decision to treat involves balancing risks and benefits with rapid assessment. As practices evolve, tenecteplase is gaining favor, especially when endovascular therapy is considered. Rapid, guideline-based intervention within the therapeutic window remains key.

For more details, healthcare professionals can refer to resources like the American Heart Association/American Stroke Association.

Step-by-Step IVT Process

1. Identify Patient: Quickly screen for suspected stroke in the emergency department.
2. Assess: Confirm symptom onset time, perform neurological exam, and rule out mimics.
3. Image Brain: Get a non-contrast CT to check for hemorrhage. Advanced imaging is used for later presentations.
4. Control BP: Lower blood pressure if it exceeds treatment limits before giving IVT.
5. Confirm Eligibility: Review all criteria.
6. Administer Thrombolytic: Give alteplase or tenecteplase per protocol.
7. Monitor: Transfer to a monitored bed for at least 24 hours.
8. Follow-up Scan: Repeat CT at 24 hours or sooner if needed, before starting antiplatelets/anticoagulants.

Comparative Analysis of Thrombolytic Agents

Consideration	Alteplase	Tenecteplase
Mechanism	Standard recombinant tPA	Modified tPA, higher fibrin specificity, longer half-life
Delivery	Bolus + 60-min infusion	Single 5-10 second bolus
Convenience	Less convenient	Highly convenient, ideal for rapid administration/transfers
Standard Use	Established, widely used	Growing evidence, favored with planned thrombectomy
Cost-effectiveness	Established, widely available	Often lower cost
Recanalization Rates	Effective, potentially less rapid	Non-inferior or potentially superior, especially for large vessel occlusions

Conclusion

The guidelines for intravenous thrombolysis in acute ischemic stroke are vital for decision-making. Adherence to patient selection, time windows, and monitoring protocols is key to optimizing outcomes and minimizing complications. The field evolves with newer agents and imaging, but rapid, guideline-based intervention remains paramount.

Frequently Asked Questions

What is the primary medication used for intravenous thrombolysis?

The primary medications used are alteplase and tenecteplase. Alteplase (tPA) has long been the standard, while tenecteplase is increasingly favored for its convenience, especially in patients who may also need mechanical thrombectomy.

What is the time limit for administering IV thrombolysis?

For most patients, IV thrombolysis must be started within 4.5 hours of the onset of stroke symptoms. In select cases guided by advanced imaging, this window can be extended.

What are the key contraindications for IV thrombolysis?

Key contraindications include evidence of intracranial hemorrhage on imaging, recent severe head trauma or surgery, active internal bleeding, and a history of intracranial hemorrhage.

How is blood pressure managed during and after IV thrombolysis?

Blood pressure must be controlled to below 185/110 mmHg before treatment. During and for 24 hours after the infusion, it must be maintained below 180/105 mmHg with frequent monitoring.

Can a patient who received IV thrombolysis also receive mechanical thrombectomy?

Yes. Patients with a large vessel occlusion should be evaluated for mechanical thrombectomy, and IV thrombolysis should not be delayed if they are eligible for both treatments.

What happens if a patient's neurological condition worsens after thrombolysis?

Immediate action is required. If the patient's neurological status declines, the thrombolytic infusion should be stopped, and an emergency CT scan of the brain must be performed to check for intracranial hemorrhage.

Is IV thrombolysis possible for 'wake-up strokes' or strokes of unknown onset?

Yes, for carefully selected patients. Using advanced imaging techniques like MRI DWI-FLAIR or CT perfusion, treatment may be initiated up to 9 hours or more after the estimated onset.