General Description

Mechanical thrombectomy has become a standard of care for acute ischemic stroke (AIS) associated with large-vessel occlusion (LVO). Numerous randomized trials have demonstrated the procedure’s effectiveness and therapeutic benefit. The studies include multicenter randomized clinical trial of endovascular treatment for AIS in the Netherlands (MR CLEAN), Endovascular treatment for small core and anterior circulation proximal occlusion with emphasis on minimizing computed tomography to recanalization times (ESCAPE), extending the time for thrombolysis in emergency neurological deficits–intra-arterial (EXTEND-IA), randomized trial of revascularization with solitaire FR device versus best medical therapy in the treatment of acute stroke caused by anterior occlusion circulation large vessel occlusion presenting within 8 hours of symptomatic onset (REVASCAT), and solitaire with the intention for thrombectomy as primary endovascular treatment (SWIFT PRIME). The “2015 AHA/ASA Focused Update of the 2013 Guidelines for Early Management of Patients with AIS” recommends endovascular treatment for patients who meet the relevant criteria. The three mechanical thrombectomy techniques most widely used today include (1) aspiration with the Penumbra system (Penumbra), (2) stent retriever with local aspiration, and (3) a direct first pass aspiration technique (ADAPT).

The ADAPT was described in 2013 by Turk et al. ¹ Large-bore catheters were positioned over the thrombus, and aspiration was applied using a syringe or an aspiration pump. The initial publication reported a 75% success rate, with complete recanalization in 57% of cases. Most recent case series of the ADAPT have reported a success rate of 73.3% with complete recanalization in 90.2% of patients. Newer large-bore trackable aspiration catheters have been partially responsible for this technique’s success. The advantages of ADAPT over stent retrieval is a quicker time to recanalization than is reported in many studies and, with the ADAPT, the thrombus is not crossed prior to its removal, theoretically decreasing the risk of distal emboli.

Indications

Mechanical thrombectomy is indicated in AIS because of LVO (occlusion in the internal carotid artery [ICA], middle cerebral artery [MCA] M1 and M2 branches, anterior cerebral artery, or posterior circulation), resulting in a National Institutes of Health Stroke Scale (NIHSS) score > 6. Intervention should be carried out within 6 hours of symptoms, or if the patient has perfusion imaging revealing a large penumbra with little or no ischemic core. If intravenous thrombolysis is contraindicated (e.g., warfarin-treated with a therapeutic international normalized ratio), mechanical thrombectomy is recommended as first-line treatment in LVO.

General Anatomy

The ICA normally originates from the common carotid artery (CCA) at the C3-4 or C4-5 vertebral level; it may occur as low as T2 and as high as C1. The petrous portion of the ICA runs forward and medial to the area of the foramen lacerum where it moves superiorly into the cavernous sinus and creates a siphon upon itself before exiting at the distal dural ring. The first branch beyond the distal ring (subarachnoid) is typically the ophthalmic artery, followed by the communicating segment of the vessel. The ICA bifurcates into the first segment of the anterior cerebral artery (A1) and the M1 segment of the MCA. The M1 segment (4–5 mm diameter) can have accessory and duplicated branches. Perforators going to the basal ganglia (i.e., lenticulostriate arteries) arise from the superior surface of the M1, and care should be taken to avoid inadvertent selection of these with the microwire. The MCA bifurcates (sometimes trifurcates) again near the bottom of the sylvian fissure (this can be variable), and an inferior branch proceeds to the M3 and M4 MCA segments over the temporoparietal region. The superior M2 division moves frontally, supplying the M3 and M4 vessels to Broca’s area as well as the motor area. Vessels in patients with AIS can have severe intracranial atherosclerotic disease, and thrombi can form at these sites as well.

Periprocedural Medications

Mechanical thrombectomy procedures are usually performed while the patient is awake and under little or no sedation. Typically, the patient has received intravenous tissue plasminogen actuator (t-PA) 1–2 hours prior to the intervention. No other medication is required for ADAPT intervention.

Specific Technique and Key Steps

1. 
   

   Most centers require specific times to be recorded for groin access, initial digital subtraction angiography (DSA) runs, microcatheter and device deployment times, and final recanalization times.

   
   
2. 
   

   A 6 French (F) or 8F sheath is inserted in the femoral artery, and femoral angiography is performed.

   
   
3. 
   

   A guide catheter (e.g., Neuron MAX, Penumbra or Shuttle Select, Cook Medical, 80 or 90 cm) is connected to a copilot valve and a continuous heparinized saline flush. An intermediate catheter (e.g., VTK, Cook Medical, 125 cm) over a 0.035-inch or 0.038-inch Glidewire (Terumo) is inserted through the copilot valve into the guide catheter. This construct is navigated up to the aortic arch and into the CCA ( Fig. 17.1, 17.2, Video 17.1, 17.2 ).

   
   
4. 
   

   Cervical carotid artery DSA runs are obtained from the CCA before advancing the guide catheter under roadmap guidance into the ICA (if the ICA diameter is large enough to accommodate the guide catheter; otherwise, the guide catheter is kept at the CCA).

   
   
5. 
   

   Anteroposterior and lateral runs of the cranial portion of the carotid artery are performed, and the site of occlusion is identified ( Video 17.1, 17.2 ).

   
   
6. 
   

   The assembled intermediate large-bore aspiration catheter (e.g., Sofia Plus, MicroVention, Terumo; 64 ACE or 68 ACE, Penumbra) with microcatheter–microwire combination is then inserted into the guide catheter. Under fluoroscopic guidance, the microwire–microcatheter, followed by the intermediate catheter, are advanced to the proximal portion of the thrombus without crossing it ( Video 17.1, 17.2 ).

   
   
7. 
   

   The intermediate catheter is gently advanced to the proximal clot interface, and the microsystem is removed. Aspiration with a pump is performed with tubing connected to the intermediate large-bore aspiration catheter. Aspiration can also be performed using a large syringe. The suction canister is monitored to determine whether the occlusive clot is present ( Video 17.1, 17.2 ).

   
   
8. 
   

   After 4–5 minutes, the aspiration catheter is carefully withdrawn under suction into the guide catheter and out of the patient. Aspiration is accomplished through the guide catheter with two large (30 cc) syringes. The guide catheter is checked for clot after the aspiration catheter is removed ( Video 17.1, 17.2 ).

   
   
9. 
   

   The large-bore aspiration catheter is flushed on the back table and checked for clot. The microwire/microcatheter is reassembled within the aspiration catheter in the event another pass is needed.

   
   
10. 
    

    Post-thrombectomy DSA runs are performed. If the clot is removed and thrombolysis in cerebral infarction 2b or 3 achieved, the procedure is done and the patient’s neurologic status should be checked ( Fig. 17.1, 17.2, Video 17.1, 17.2 ). If the clot persists (indicated by the clinical examination findings or the presence of clot extravasation), another ADAPT pass is performed. At this point, consideration is given to switching to the stent retriever/aspiration technique.

    
    
11. 
    

    After successful intracranial revascularization and removal of the guide catheter, CCA runs are performed to ensure patency and integrity of the ICA.

    
    
12. 
    

    The guide catheter is removed, and the femoral arteriotomy is closed with an AngioSeal vascular closure device (Terumo).

    
    
13. 
    

    If the patient is stable and more information on collateral supply is needed, a full diagnostic angiogram can be completed.