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How to do a mechanical thrombectomy

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mechanical thrombectomy stroke procedure stent retriever

A native fluoroscopic image (X-ray) in an anteroposterior (AP) view showing a mechanical thrombectomy procedure for an ischemic stroke. The image demonstrates a radio-opaque stent retriever deployed within the intracranial vasculature. An arrow points to the distal radio-opaque markers of the device, which is positioned at the level of the left carotid terminus (the bifurcation of the internal carotid artery into the middle cerebral artery and anterior cerebral artery). Below this, the proximal delivery catheter and markers are visible as they ascend through the cervical and petrous segments of the internal carotid artery. The surrounding cranial anatomy, including the calvarium, orbits, and petrous ridges, provides anatomical context for the endovascular positioning. This clinical image illustrates a key step in interventional neuroradiology where the device is used to engage and extract a thrombus to restore cerebral perfusion.

A native fluoroscopic image (X-ray) in an anteroposterior (AP) view showing a mechanical thrombectomy procedure for an ischemic stroke. The image demonstrates a radio-opaque stent retriever deployed within the intracranial vasculature. An arrow points to the distal radio-opaque markers of the device, which is positioned at the level of the left carotid terminus (the bifurcation of the internal carotid artery into the middle cerebral artery and anterior cerebral artery). Below this, the proximal delivery catheter and markers are visible as they ascend through the cervical and petrous segments of the internal carotid artery. The surrounding cranial anatomy, including the calvarium, orbits, and petrous ridges, provides anatomical context for the endovascular positioning. This clinical image illustrates a key step in interventional neuroradiology where the device is used to engage and extract a thrombus to restore cerebral perfusion.

Two lateral fluoroscopic/angiographic views of the skull demonstrating an endovascular mechanical thrombectomy procedure in the cerebral vasculature. The images illustrate the triaxial spatial arrangement of interventional devices. A Solitaire stent retriever (1) is deployed distally within a cerebral artery, likely the internal carotid or middle cerebral artery, to engage a thrombus. Proximally, the Advanced Neurovascular Access (ANA) device is positioned, featuring an expanded, radiopaque braided funnel (2) that apposes the vessel walls to provide local flow restriction and enhanced aspiration. The ANA delivery catheter (3) is seen coaxially aligned with the funnel system. A larger guide catheter (4) is visible in the more proximal vasculature, providing the primary access route. The clinical significance of this setup is to show the combined use of a stent retriever with a specialized aspiration funnel to optimize clot retrieval and minimize distal embolization during acute ischemic stroke intervention. This material is suitable for intermediate to advanced neurointerventional training.

Two lateral fluoroscopic/angiographic views of the skull demonstrating an endovascular mechanical thrombectomy procedure in the cerebral vasculature. The images illustrate the triaxial spatial arrangement of interventional devices. A Solitaire stent retriever (1) is deployed distally within a cerebral artery, likely the internal carotid or middle cerebral artery, to engage a thrombus. Proximally, the Advanced Neurovascular Access (ANA) device is positioned, featuring an expanded, radiopaque braided funnel (2) that apposes the vessel walls to provide local flow restriction and enhanced aspiration. The ANA delivery catheter (3) is seen coaxially aligned with the funnel system. A larger guide catheter (4) is visible in the more proximal vasculature, providing the primary access route. The clinical significance of this setup is to show the combined use of a stent retriever with a specialized aspiration funnel to optimize clot retrieval and minimize distal embolization during acute ischemic stroke intervention. This material is suitable for intermediate to advanced neurointerventional training.

This composite of six digital subtraction angiography (DSA) and fluoroscopic images illustrates a mechanical thrombectomy procedure for acute ischemic stroke. Panels A (anteroposterior) and B (lateral) show the pre-intervention state with proximal occlusions in the left A1 segment of the anterior cerebral artery (ACA), the superior M1 proximal branch, and the inferior Sylvian M2 branch of the middle cerebral artery (MCA), characterized by an abrupt cutoff of contrast flow. Panels C and D demonstrate the intra-procedural combined technique using a balloon guide catheter (BGC), a distal access catheter (DAC), and a stent retriever. The BGC balloon is visibly inflated in the internal carotid artery (ICA) to arrest antegrade flow, while the stent retriever is deployed across the occluded segments. Panels E and F provide the post-intervention angiographic results, showing successful recanalization of the ACA and MCA territories with restored distal perfusion. The series demonstrates the endovascular management of complex intracranial arterial occlusions using modern aspiration and stent-retriever techniques.

This composite of six digital subtraction angiography (DSA) and fluoroscopic images illustrates a mechanical thrombectomy procedure for acute ischemic stroke. Panels A (anteroposterior) and B (lateral) show the pre-intervention state with proximal occlusions in the left A1 segment of the anterior cerebral artery (ACA), the superior M1 proximal branch, and the inferior Sylvian M2 branch of the middle cerebral artery (MCA), characterized by an abrupt cutoff of contrast flow. Panels C and D demonstrate the intra-procedural combined technique using a balloon guide catheter (BGC), a distal access catheter (DAC), and a stent retriever. The BGC balloon is visibly inflated in the internal carotid artery (ICA) to arrest antegrade flow, while the stent retriever is deployed across the occluded segments. Panels E and F provide the post-intervention angiographic results, showing successful recanalization of the ACA and MCA territories with restored distal perfusion. The series demonstrates the endovascular management of complex intracranial arterial occlusions using modern aspiration and stent-retriever techniques.

This composite figure illustrates a mechanical thrombectomy procedure for acute ischemic stroke using digital subtraction angiography (DSA) and fluoroscopic guidance. Panel A shows a frontal radiograph of the skull and neck during the initial phase. A red arrow indicates the site of a direct left common carotid artery (CCA) puncture. Visible external monitoring equipment includes multiple EEG electrodes adhered to the scalp and an endotracheal tube. Panel B provides a high-magnification fluoroscopic view of the neurointerventional procedure. Red arrowheads track the deployment of a stent retriever (Solitaire X) extending from the M2 segment of the middle cerebral artery to the terminal internal carotid artery (ICA), alongside a REACT71 aspiration catheter. Panel C presents a post-procedural DSA image demonstrating successful TICI 2b recanalization of the previously occluded left internal carotid artery and its distal branches. The content highlights advanced neurovascular rescue techniques and the specific approach of direct carotid access for mechanical thrombectomy in complex aortic anatomy.

This composite figure illustrates a mechanical thrombectomy procedure for acute ischemic stroke using digital subtraction angiography (DSA) and fluoroscopic guidance. Panel A shows a frontal radiograph of the skull and neck during the initial phase. A red arrow indicates the site of a direct left common carotid artery (CCA) puncture. Visible external monitoring equipment includes multiple EEG electrodes adhered to the scalp and an endotracheal tube. Panel B provides a high-magnification fluoroscopic view of the neurointerventional procedure. Red arrowheads track the deployment of a stent retriever (Solitaire X) extending from the M2 segment of the middle cerebral artery to the terminal internal carotid artery (ICA), alongside a REACT71 aspiration catheter. Panel C presents a post-procedural DSA image demonstrating successful TICI 2b recanalization of the previously occluded left internal carotid artery and its distal branches. The content highlights advanced neurovascular rescue techniques and the specific approach of direct carotid access for mechanical thrombectomy in complex aortic anatomy.

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Now I have everything needed for a thorough answer. Here it is:

Mechanical Thrombectomy

Mechanical thrombectomy is an endovascular procedure used to physically remove a thrombus from an occluded vessel - most commonly applied in acute ischemic stroke due to large vessel occlusion (LVO), but also used for peripheral arterial occlusion. Both contexts are covered below.

Part 1 - Intracranial / Stroke Thrombectomy

Patient Selection & Timing

AHA/ASA guidelines recommend mechanical thrombectomy for adults who have all of the following (0-6 hour window):
  • No significant prestroke disability (mRS ≤ 1)
  • Causative occlusion of the ICA or M1 segment of MCA
  • NIHSS ≥ 6
  • ASPECTS ≥ 6 on imaging
Extended windows (6-24 hours): Patients meeting DAWN or DEFUSE 3 criteria (large vessel occlusion in anterior circulation with favourable perfusion imaging mismatch) may still benefit. The DAWN trial used clinical/imaging mismatch criteria; DEFUSE 3 used CT perfusion or DWI-MRI. Pre-treatment with IV alteplase (if within 4.5 hours) is NOT required before proceeding to thrombectomy.
  • Bradley and Daroff's Neurology in Clinical Practice, p. 1132
  • ROSEN's Emergency Medicine, p. 1439

Step-by-Step Procedure

1. Setup & Access

  • Performed in an angiography suite under fluoroscopic guidance
  • Femoral artery access is standard (radial or direct carotid access used in complex anatomy)
  • A guide catheter (often a balloon guide catheter, BGC) is placed in the cervical ICA or vertebral artery
  • The BGC allows balloon inflation to arrest antegrade flow during clot retrieval, reducing distal embolization

2. Diagnostic Angiography

  • Digital subtraction angiography (DSA) confirms the vessel occlusion site (ICA terminus, M1, M2, basilar artery)
  • Roadmap imaging is acquired to navigate distally

3. Microcatheter Navigation

  • A microwire (e.g. Synchro 14) is used to cross the occlusion, followed by a microcatheter
  • A distal access catheter (DAC) is advanced coaxially as close to the clot as possible

4. Device Deployment - Two Main Techniques

A. Stent Retriever (most widely used)
The stent retriever (e.g. Solitaire FR - Medtronic, Trevo - Stryker, EmboTrap - Cerenovus) is deployed through the microcatheter across the thrombus:
MERCI clot retrieval device and mechanism of action - spiral loops engage and remove thrombus
  • The stent is deployed and expands within the clot, incorporating it into the mesh
  • After 3-5 minutes of dwell time (to allow thrombus integration), the BGC balloon is inflated to stop flow
  • The stent retriever is slowly withdrawn with continuous aspiration applied through the DAC or guide catheter
  • The ASTER and COMPASS trials showed direct aspiration first-pass (ADAPT) was non-inferior to stent retriever as first-line therapy
B. Direct Aspiration (ADAPT technique)
  • A large-bore aspiration catheter (e.g. Penumbra/Sofia/React 71) is advanced directly to the clot face without a stent retriever
  • A vacuum is applied, engaging the thrombus at the catheter tip
  • The catheter is withdrawn with continuous suction, removing the clot en bloc
  • If the clot does not come free, a stent retriever can be added (combined technique)
Combined Technique (stent retriever + aspiration funnel):
Triaxial setup - Solitaire stent retriever with ANA aspiration funnel and guide catheter for combined thrombectomy

5. Post-Retrieval Angiography

  • Perform runs to confirm reperfusion grade using TICI scoring:
    • TICI 2b/3 = successful reperfusion (goal)
    • TICI 0/1 = failed reperfusion
  • If residual stenosis is identified (e.g. due to underlying intracranial atherosclerotic disease), angioplasty +/- stenting may be considered
Here is an example of pre- and post-thrombectomy DSA:
DSA images showing pre-thrombectomy LVO occlusion and post-procedure recanalization of ACA/MCA territory

6. Repeat Passes

  • Multiple passes may be needed (typically up to 3 attempts)
  • Each pass increases risk of vessel injury and hemorrhagic transformation

Part 2 - Peripheral Arterial Thrombectomy

Used for acute limb ischemia (ALI), especially Rutherford IIb (immediately threatened limb) when rapid revascularization is needed.

Preoperative Planning

  • Mechanical thrombectomy has reduced bleeding risk versus catheter-directed thrombolysis (CDT) when tPA is NOT used
  • Suitable for patients who have contraindications to tPA (recent surgery, intracranial hemorrhage)
  • Arterial access obtained, vascular sheath placed, diagnostic angiography performed
  • Current Surgical Therapy 14e, p. 1637

Devices

AngioJet (Boston Scientific) - Rheolytic Thrombectomy:
  • End-hole catheter with side holes that expel saline jets while simultaneously aspirating
  • The rheolytic action mechanically disrupts and extracts thrombus
  • Technique: wire traverses the occlusion → AngioJet catheter is advanced → device activated → catheter slowly advanced and retracted with intermittent rotation to cover all clot
  • "Power Pulse" mode infuses tPA with the expelled fluid for a pharmacomechanical hybrid approach, followed by a conventional pass after a dwell period
  • Complications: hemolysis, hemoglobinuria, hyperkalemia, acute kidney injury (limit device run time); microembolization (consider distal protection devices)
Indigo (Penumbra) - Aspiration Thrombectomy:
  • Flexible "CAT" catheter connected to a continuous vacuum engine
  • Catheter advanced to thrombus, wire removed, vacuum applied via flow switch
  • Catheter retracted until blood seen in canister, then suction rapidly disengaged
  • Monitor canister carefully - rapid exsanguination can occur
  • Newer models include automated blood-flow cessation systems

Post-Procedure Care

  • Serial neurovascular examinations of the limb
  • Monitor for reperfusion compartment syndrome - prophylactic 4-compartment fasciotomies recommended if ischemia >6 hours or if limb edema develops post-reperfusion
  • Watch for rhabdomyolysis: target urine output >100 cc/hour, urine alkalinization with bicarbonate if CPK is rising
  • After successful revascularization, patients require long-term anticoagulation to prevent re-thrombosis

Key Evidence Summary

TrialWindowFinding
MR CLEAN, ESCAPE, EXTEND-IA, SWIFT PRIME, REVASCAT0-6 hStent retriever thrombectomy superior to standard care for anterior LVO
DAWN6-24 hBenefit in selected patients with clinical-imaging mismatch
DEFUSE 36-16 hBenefit with perfusion mismatch imaging selection
ASTER / COMPASS0-6 hAspiration (ADAPT) non-inferior to stent retriever as first-line
ARISE II-EmboTrap: 80% TICI ≥2b, 67% mRS 0-2 at 90 days
Each 1-hour delay from symptom onset to reperfusion is independently associated with worse disability outcomes - "time is brain."
  • Bradley and Daroff's Neurology in Clinical Practice, p. 1132-1134
  • ROSEN's Emergency Medicine, pp. 1439-1441
  • Current Surgical Therapy 14e, pp. 1637-1638
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