General Description

Atherosclerotic stenosis may be the underlying cause for an acute ischemic stroke. Approximately 8%–10% of ischemic strokes in the United States are attributed to intracranial atherosclerotic disease (ICAD). This accounts for nearly 80,000 new strokes per year. The pathophysiology behind these plaques is similar to plaques in the extracranial vasculature as well. Thrombosis at the site of stenosis secondary to plaque rupture or hemorrhage or progressive occlusive plaque growth can lead to acute ischemic large-vessel occlusions. ICAD tends to affect the middle cerebral artery (MCA) and internal cerebral artery (ICA), although nearly 40% of ICAD-related strokes are in the posterior circulation. Although medical management with antiplatelet therapy was shown to be a good first-line therapy, in the setting of acute large-vessel occlusion, intervention is prudent and management of the underlying stenosis may be warranted.

Evidence for Mechanical Thrombectomy with Intracranial Stenting/Angioplasty

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  The Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN) demonstrated an absolute difference of 13.5 percentage points (95% CI, 5.9 to 21.2) in the rate of functional independence (modified Rankin Scale [mRS] score, 0 to 2) at 90 days in favor of the intervention (32.6% vs. 19.1%).

  
  
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  Endovascular treatment for small core and anterior circulation proximal occlusion with emphasis on minimizing CT to recanalization times (ESCAPE) demonstrated that endovascular intervention had favorable 90-day outcomes (mRS score, 0–2) in 53% of patients, which was statistically better than the control group with only 29% favorable outcomes.

  
  
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  Solitaire with the intention for thrombectomy as primary endovascular treatment (SWIFT PRIME) was a 39-center international randomized trial demonstrating a significant benefit for endovascular therapy in 90-day favorable outcome (mRS score, 0–2) with a p < 0.001.

  
  
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  Stenting of symptomatic atherosclerotic lesions in the vertebral or intracranial arteries (SSYLVIA) demonstrated a 30-day stroke rate of 7.2% and delayed stroke rate of 10.9%, improving on outcomes from stenting and aggressive medical management for preventing recurrent stroke in intracranial stenosis (SAMMPRIS).

  
  
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  In 2017, Yi et al. ¹ evaluated 12 consecutive patients with large-vessel occlusions requiring balloon-assisted or stent-assisted angioplasty for ICAD demonstrating successful recanalization with an mRS score of <2 in 11 of 12 patients.

Indications

Preoperative imaging can guide treatment planning for patients with acute ischemic stroke. Indications for concomitant stenosis on imaging can suggest underlying ICAD and can alert the physician of a need to consider angioplasty or stenting for recalcitrant disease. Imaging with calcification in the wall of the affected vessel, long-segment occlusion, or clinical risk factors of atherosclerosis may point to a possible need for angioplasty or stenting after mechanical thrombectomy. The optimal intervention depends largely on the accessibility and caliber of the affected vessel. In the acute setting, angioplasty offers the advantage of not requiring antiplatelet therapy prior to intervention, although the risks associated with oversizing the balloon are compounded in this scenario. Angioplasty may also be preferred in tortuous anatomy, offering an easier solution to quickly reperfuse the affected cortex. Recalcitrant thrombus and persistent occlusion secondary to ICAD and dissection are best treated with stenting to maintain patency of the vessel, at least in the short term.

Neuroendovascular Anatomy

ICAD affects nearly all intracranial large vessels. The most common intracranial large vessels affected in decreasing order of frequency include the MCA (33.9% of cases), ICA (20.3%), basilar artery (20.3%), and vertebral artery (19.6%), followed by other intracranial vessels (5.9%). The MCA is conventionally divided into four segments: M1, from the origin to the bifurcation at the limen insulae; M2, the insular segment where it hairpin turns to lead into the operculum; M3, opercular branches within the Sylvian fissure; and M4, branches emerging from the Sylvian fissure on the convex surface of the hemisphere. The M1 segment and proximal M2 segment are frequently involved in the setting of ICAD and large-vessel occlusive lesions. Preoperative imaging can help to plan possible intervention relative to the caliber of the affected vessel.

In the posterior circulation, large-vessel occlusion of the vertebral artery may not warrant emergent intervention if the contralateral vertebral artery is sufficiently supplying the posterior circulation. Large-vessel occlusion of the basilar artery with underlying stenosis may warrant angioplasty over stenting given the rich perforator zones.

Periprocedural Medications

Dual antiplatelet therapy with aspirin (325 mg daily) and ticagrelor (90 mg daily) is prescribed for patients undergoing emergent stenting. An aspirin loading dose of 650 mg and a ticagrelor loading dose of 180 mg are typically given 30 minutes prior to deployment of the stent in an emergent setting. In the setting of tissue plasminogen activator (tPA) being given for acute ischemic stroke, understanding the elevated risk of symptomatic intracranial hemorrhage is important when deciding to administer a loading dose of dual antiplatelet agents. In this acute setting, angioplasty may be preferred.

If tPA is not administered, a weight-based intravenous bolus of heparin aimed at an activated clotting time (ACT) of 250–300 s may limit thromboembolic complications. Administering heparin before crossing the stenotic lesion may limit thrombus formation at the proximal end of the stenosis. For acute thrombus formation during the procedure, a glycoprotein (GP) IIb/IIIa inhibitor (e.g., eptifibatide) can be used intraprocedurally.

If angioplasty is performed for ICAD without stenting, the patient should be started on aspirin (325 mg daily) and clopidogrel (75 mg daily) in the post-procedure period.

Specific Technique and Key Steps

Submaximal angioplasty for IAD tends to use undersized noncompliant balloons to allow for appropriate pressure and management while inflating the balloon (Fig 20.1, 20.2, Video 20.1, 20.2):

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   A 6, 8, or 9 French (F) sheath is inserted in the femoral artery.

   
   
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   After the femoral angiogram has been performed to confirm the absence of any irregularity or dissection, a guide catheter is advanced over a 0.035-inch curved wire into the aorta. This maneuver is completed under fluoroscopic guidance.

   
   
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   The guide catheter is advanced into the distal internal carotid artery. The guide catheter can be brought over a select catheter and 0.035-inch glide wire.

   
   
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   Cerebral angiography is performed to obtain a baseline set of images of the intracranial vasculature (Video 20.1, 20.2).

   
   
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   The aspiration catheter over the microcatheter over a microwire is used to navigate the intracranial vasculature under roadmap guidance to the site of the occlusion.

   
   
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   The microwire is used to cross the lesion and the microcatheter is advanced past the lesion and microcatheter injections are performed.

   
   
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   A stent retriever is then deployed distal to the occlusion and covering the site of the occlusion.

   
   
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   Using the Solumbra technique, the aspiration catheter is advanced to the unsheathed stent retriever and both are removed from the guide concomitantly.

   
   
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   Thrombectomy attempts typically may be repeated three times. If persistent stenosis is noted, angioplasty may be warranted (Video 20.1, 20.2).

   
   
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    Under roadmap guidance, a microwire backloaded into a noncompliant balloon can be used to navigate past the stenotic lesion.

    
    
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    Selection of the balloon:

    
    
    
    
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       Noncompliant balloon (Gateway, Stryker; Sprinter, Medtronic; Maverick, Boston Scientific)—used for lesions measuring 1 mm in size, can be inflated to subnominal pressures of 4 atm in 2-3 mm MCA or basilar-sized vessels.

       
       
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       Compliant balloons (Scepter, MicroVention)—used for lesions near branch points if concern for soft plaque is present.

       
       
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       Minimally compliant coronary balloons—used in vessels of 1.25 mm and 1.5 mm with the ability to measure atmospheres of pressure to correlate with balloon diameter so as to perform submaximal angioplasty.

    
    
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    The patient is systemically heparinized with an ACT in the range of 250–300 s if tPA was not administered.

    
    
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    The balloon is connected to an insufflator and inflated under fluoroscopy to a nominal pressure at the rate of 1 atm/min and subsequently deflated at a rate of 1 atm/15 s.

    
    
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    If the stenosis is recalcitrant, the balloon may be exchanged out while leaving the microwire in place past the lesion.

    
    
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    A Wingspan stent (Stryker) can be backloaded onto the microwire and under roadmap guidance, is advanced up to the lesion (Fig 20.1, 20.2, Video 20.1, 20.2).

    
    
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    Under roadmap guidance and high-powered magnification, the Wingspan stent is deployed over the large-vessel occlusion. Maintaining distal microwire access, angiographic runs are performed to demonstrate recanalization (Fig 20.1, 20.2, Video 20.1, 20.2).

    
    
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    Final cerebral angiographic runs are performed, and the microwire and guide catheter are removed.