General Description

Acute tandem occlusion involving the cervical internal carotid artery (ICA) with concomitant intracranial thromboembolism to the intracranial ICA terminus or middle cerebral artery (MCA) is estimated to occur in 15% of all cases of large-vessel occlusion (LVO) acute ischemic stroke (AIS). These lesions are challenging to manage endovascularly and respond poorly to intravenous tissue plasminogen activator (tPA). Tandem lesions typically have a worse prognosis than a lone intracranial lesion and are associated with higher rates of symptomatic intracranial hemorrhage (ICH), with one small series reporting a 22% rate of symptomatic ICH and a 39% rate of 90-day mortality.

Compared with intracranial occlusion alone, tandem occlusion presents a difficult pathology that is associated with increased risk of morbidity and mortality. Typically, the extracranial occlusion is a result of atherosclerotic plaque with or without thrombus; however, dissections are also a possible cause. Two techniques exist for tandem occlusions: (1) anterograde stenting with thrombectomy, and (2) intracranial thrombectomy followed by retrograde stenting. This chapter describes the use of either technique in the setting of extracranial tandem occlusion or common carotid artery (CCA)/ICA occlusion concurrent with acute intracranial occlusion. Vessel perforation and reperfusion hemorrhage are the two main concerns associated with the techniques. Patient selection can help to minimize risk.

Indications

Mechanical thrombectomy and carotid artery stenting (CAS) are indicated for AIS because of cervical ICA occlusion and LVO (ICA or MCA M1 and M2 branches) 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. Computed tomographic (CT) angiography of the head and neck vessels is necessary to make a diagnosis of tandem occlusion and plan treatment adequately. We prefer stenting to angioplasty alone to prevent restenosis and continued embolization; however, an antiplatelet regimen must be prescribed in conjunction with stenting procedures.

Neuroendovascular Anatomy

The ICA normally originates from the 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 ICA bifurcates into the first anterior cerebral artery segment (A1) and the first segment of the MCA (M1). 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 a microwire. The MCA bifurcates (trifurcates on occasion) again near the bottom of the sylvian fissure, and an inferior branch proceeds to the M3 and M4 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 (ICAD). Thrombi can form at these disease sites as well. Furthermore, some patients can become symptomatic from ICAD stenosis caused by hypoperfusion; and the symptoms can mirror AIS; however, typically, in this situation, thrombectomy is not needed. Surgical or endovascular revascularization with angioplasty or bypass is necessary in those types of cases.

Periprocedural Medications

Anterograde stenting with thrombectomy and intracranial thrombectomy followed by retrograde stenting procedures are usually performed with the patient awake and under little or no sedation. Typically, the patient has received tPA, and further anticoagulation or antiplatelets are contraindicated. A loading dose of aspirin (650 mg) and clopidogrel (600 mg) or ticagrelor (180 mg) is administered preprocedurally.

Specific Technique and Key Steps

1. 
   

   All necessary catheters are assembled on a table at the back of the angiography suite and connected to heparinized flushes. They are laid out on the angiogram table coaxially.

   
   
2. 
   

   Access is obtained via a femoral arteriotomy performed, if possible, with the use of a micropuncture set. A 6 or an 8 French (F) sheath is inserted. Under fluoroscopy, the microwire should be deemed appropriate in relation to the femoral head before dilating up to a larger size sheath. If an 8F sheath is placed, a transitional 6F dilator is utilized. A 9F sheath is necessary when a balloon-guide catheter is used (e.g., 9F MoMa dual balloon-guide catheter, Medtronic).

   
   
3. 
   

   The guide sheath (90 cm length) with Copilot Valve is placed over an intermediate catheter (e.g., VTK 125-cm diagnostic catheter, Cook Medical) and over a glidewire (e.g., Glidewire Advantage 180 cm, Terumo) and advanced into the CCA.

   
   
4. 
   

   Digital subtraction angiography (DSA) runs are taken from the CCA prior to advancing the guide catheter into the ICA under roadmap guidance ( Fig. 21.1, 21.2, Video 21.1, 21.2 ).

   
   
5. 
   

   The extracranial occlusion is identified, and working roadmap views are obtained.

   
   
6. 
   

   If the extracranial vessel is occluded and distal flow is absent, gentle suction through the guide or intermediate catheter can be utilized prior to crossing the occlusion with the microcatheter ( Video 21.1, 21.2 ).

   
   
7. 
   

   If the microcatheter cannot be advanced across the stenotic/occlusive extracranial lesion, balloon angioplasty may be necessary. This can be performed under flow arrest with a balloon-guide catheter. Once the microcatheter is beyond the lesion, microinjection can be performed to ensure that the length of the lesion is covered by the stent ( Video 21.1, 21.2 ).

   
   
8. 
   

   A stent is then navigated through the stenosis/occlusion and deployed under fluoroscopy. A post-balloon angioplasty is utilized if stenosis remains after stent placement ( Fig 21.1, 21.2, Video 21.1, 21.2 ).

   
   
9. 
   

   Intracranial anteroposterior and lateral DSA runs are performed, and the intracranial occlusion site is identified.

   
   
10. 
    

    An assembled triaxial system that includes an intermediate large-bore aspiration catheter (e.g., Sofia or Sofia Plus, MicroVention; 5 MAX or 64 aspiration catheter, Penumbra), a 0.0027-inch microcatheter (Headway, MicroVention; Velocity, Penumbra; Marksman, Medtronic), and a 0.0014-inch microwire is then inserted into the guide catheter. Under fluoroscopy, the microwire and microcatheter followed by the intermediate catheter are advanced to, but not beyond, the site of the intracranial occlusion with care taken to account for any built-up tension in the system while nearing the thrombus. A direct aspiration first pass technique (ADAPT) or stent-retriever technique can be utilized at this point ( Video 21.1, 21.2 ).

    
    
11. 
    

    When using stent retrievers, some interventionists cross the lesion with a microwire under suction from the intermediate catheter. In any case, the lesion must be crossed with the microwire and microcatheter if a stent retriever is used. The microwire can then be withdrawn and a microinjection performed to ensure that the vasculature distal to the occlusion is patent.

    
    
12. 
    

    The stent retriever is then appropriately sized for the vessel. A 4-mm device is usually sufficient for M1 and beyond. Longer devices can be selected for longer clots.

    
    
13. 
    

    The device is pushed into the rotating hemostatic valve and back flushed. Next, the device is loaded into the microcatheter. Fluoroscopy should be utilized to push the device beyond the fluoro save marker. The catheter is pinned, and the device is pushed to the end of the catheter and beyond the clot. The ideal landing zone for the retriever is to have the clot at the mid to proximal area of the retriever ( Fig 21.1, 21.2, Video 21.1, 21.2 ).

    
    
14. 
    

    After 3 minutes of deployment, some interventionists obtain microinjections to assess for recanalization. The microcatheter is removed, pinning the stent. The intermediate large-bore aspiration catheter is turned to suction after 3–5 minutes, and the stent retriever is slowly withdrawn into the intermediate catheter. In those cases in which a carotid stent has been placed to treat the extracranial lesion, stent-retriever removal must be accomplished under fluoroscopy. The stent retriever is observed to make sure that it is not caught with the cervical stent. This event is unlikely, but it can occur.

    
    
15. 
    

    The stent retriever is inspected for clot. Final runs are obtained to determine whether contrast extravasation is present and another pass is needed. The intermediate catheter is also withdrawn under suction and inspected for clot. The guide catheter should be aspirated with two large (30 mL) syringes.

    
    
16. 
    

    Post-thrombectomy DSA runs are performed. If the clot is removed and a thrombolysis in cerebral infarction grade of 2b or 3 is achieved, the procedure is done, and the patient’s neurologic status should be checked. If the clot persists, consideration is given to whether another pass is needed ( Video 21.1, 21.2 ).

    
    
17. 
    

    After removing the guide catheter, CCA runs are performed as well as a groin run (if not already performed) to determine eligibility for a closure device (e.g., AngioSeal, Terumo).

    
    
18. 
    

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