What are the steps for mechanical thrombectomy in a patient with acute ischemic stroke?

Mechanical Thrombectomy Procedure Steps

Mechanical thrombectomy for acute ischemic stroke follows a systematic approach from patient selection through post-procedure reperfusion assessment, with the technical goal of achieving mTICI 2b/3 reperfusion as rapidly as possible. 1

Pre-Procedure Patient Selection and Imaging

Initial Assessment (0-6 Hour Window)

• Obtain non-contrast CT head immediately to exclude hemorrhage and calculate ASPECTS score (must be ≥6) 2
• Perform CT angiography simultaneously to confirm large vessel occlusion of the internal carotid artery or MCA M1 segment 1, 2
• Verify eligibility criteria: age ≥18 years, pre-stroke mRS 0-1, NIHSS ≥6, and ability to achieve groin puncture within 6 hours of symptom onset 1, 3
• Do not delay procedure for laboratory results except blood glucose measurement; obtain aPTT and INR but proceed without waiting for results 2

Extended Window Assessment (6-24 Hours)

• Require advanced imaging with CTP or DW-MRI to demonstrate sizable mismatch between ischemic core and hypoperfusion area 1, 2
• Strictly adhere to DAWN or DEFUSE-3 eligibility criteria for patient selection in this time window 1, 3
• Use clinical-imaging mismatch (combination of NIHSS score and perfusion imaging findings) as demonstrated in the DAWN trial 1

Concurrent IV Thrombolysis Management

• Administer IV alteplase (0.9 mg/kg, maximum 90 mg) if eligible, even when mechanical thrombectomy is planned 1, 3
• Do not evaluate response to IV thrombolysis before proceeding with catheter angiography—proceed directly to thrombectomy without delay 1, 3
• Lower blood pressure below 185/110 mmHg before initiating IV thrombolysis in hypertensive patients 1

Procedural Technique

Vascular Access and Navigation

• Achieve femoral artery access and advance guide catheter to the cervical internal carotid artery or vertebral artery 4
• Perform diagnostic angiography to confirm occlusion location and assess collateral circulation 4
• Navigate microcatheter and microwire beyond the thrombus under fluoroscopic guidance 4

Thrombectomy Execution

• Use stent retrievers or direct aspiration as primary thrombectomy techniques 1, 4
• Deploy stent retriever across the thrombus (if using this technique), wait 3-5 minutes for clot integration, then retrieve under continuous aspiration 4
• Alternatively, perform direct aspiration by advancing large-bore aspiration catheter to thrombus face and applying suction 4
• Consider combination techniques (stent retriever with proximal balloon guide catheter or distal aspiration) to optimize first-pass effect 4

Cervical ICA Management

• Address cervical ICA occlusion or stenosis in addition to intracranial LVO when present, as mechanical thrombectomy can be considered in these cases 1, 3

Reperfusion Assessment and Goals

• Achieve mTICI 2b/3 reperfusion as the technical endpoint to maximize probability of good functional outcome 1, 3
• Perform angiographic runs after each thrombectomy pass to assess reperfusion grade 1
• Continue attempts until mTICI 2b/3 achieved or until further attempts pose unacceptable risk 1

Time-Critical Considerations

• Minimize door-to-groin puncture time as each 1-hour delay to reperfusion reduces favorable outcomes (adjusted odds ratio 0.84 per hour delay) 1
• Maintain time urgency equivalent to IV alteplase, as reduced time from symptom onset to reperfusion is highly associated with better clinical outcomes 1
• Achieve reperfusion within the therapeutic window: benefit retains statistical significance through 7 hours 18 minutes in the early window 1

Common Pitfalls to Avoid

• Never delay thrombectomy to observe IV thrombolysis response—this practice is not recommended and wastes critical time 3
• Do not exclude patients based on high NIHSS scores (>25-30) as severe strokes may benefit most from intervention 3
• Do not exclude elderly patients (>80 years) based on age alone as they comprise the majority of stroke victims and may still benefit 3
• Avoid using eligibility criteria other than DAWN or DEFUSE-3 for the extended time window, as these are the only validated criteria from randomized trials 1