General Description

Intracranial angioplasty can be an effective modality of treatment for symptomatic intracranial atherosclerotic disease (ICAD). Asymptomatic patients tend to do best with aggressive medical management involving dual antiplatelet therapy with aspirin 325 mg daily and clopidogrel 75 mg daily. The Warfarin Aspirin Symptomatic Intracranial Disease (WASID) trial demonstrated a 2-year stroke risk of 19.7% in patients taking aspirin with symptomatic ICAD and 17.2% in those taking warfarin. Since WASID, other studies have concluded that lifestyle modification and anticoagulation do not address the pathophysiology of chronic plaque buildup, but that there is support for the use of dual antiplatelet therapy. The Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial demonstrated that nearly one in eight symptomatic patients had recurrent strokes within 12 months of observation after stent placement for ICAD despite aggressive medical management. The final results of the SAMMPRIS trial showed an increased rate of stroke for intervention patients versus medical management at 14.7% compared to 5.8%, respectively. In addition, the Stenting of Symptomatic Atherosclerotic Lesions in the Vertebral or Intracranial Arteries (SSYLVIA) study demonstrated a lower periprocedural complication 30-day stroke rate of 7.2% and a delayed stroke rate of 10.9% using a balloon-mounted stent. Evidence subsequent to these studies has supported intracranial submaximal angioplasty for ICAD with stenting in recalcitrant cases.

Evidence for Intracranial Angioplasty

• 
  

  SSYLVIA demonstrated a 30-day stroke rate of 7.2% and a delayed stroke rate of 10.9% after intracranial angioplasty in symptomatic patients, improving on outcomes from SAMMPRIS. The Wingspan stent system (Stryker) study demonstrated a 30-day stroke rate of 6%.

  
  
• 
  

  A French study in 2011 included 63 symptomatic patients treated with submaximal angioplasty based on sizing a noncompliant balloon to match 80% of parent vessel size when inflated to nominal pressures. This study used a noncompliant Gateway Balloon Catheter (Stryker) followed by immediate Wingspan stenting. This study introduced the discussion about angioplasty alone because of the 95% success rate of improvement of flow with a 20% periprocedural complication rate and a 4.8% periprocedural permanent mortality and morbidity.

  
  
• 
  

  A study in 2012 that focused on submaximal angioplasty without stenting involved 41 patients demonstrating a 91% rate of no ischemic or perioperative symptoms or complications at 19 months’ follow-up.

  
  
• 
  

  Based on the results of a phase 1 trial, submaximal angioplasty is the ideal first surgical intervention for symptomatic intracranial stenosis that has failed aggressive medical management. The trial investigators studied 24 patients who had an average preprocedural stenosis of 80% and postprocedural stenosis of 54% with no 30-day ischemic events and a 5% rate of ischemic events at 1 year.

Indications

In the WASID trial, patients with symptomatic intracranial stenosis were found to have an 11%–12% first-year risk of stroke in the same region of stenosis, with 73% of strokes happening in the region of intracranial stenosis. Similar to extracranial carotid artery stenosis, patients with lesions measuring 50%–69% stenosis had a 6% 1-year stroke risk, whereas patients with > 70% stenosis had a 1-year stroke risk of 19%. Indications for angioplasty centered on patients who had recurrent strokes or symptoms after aggressive medical management. A review of angiographic progression of untreated stenosis noted that 40% of lesions remain stable, 20% regress, and 40% progress, thus identifying and treating lesions that progress becomes crucial.

Neuroendovascular Anatomy

ICAD primarily affects the internal carotid artery (ICA) and the middle cerebral artery (MCA) vessels. The ICA is conventionally broken into seven segments, with the last three segments being intradural. The normal luminal diameter of the ICA tends to be 3–4 mm. 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 makes a hairpin turn and leads 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 normal luminal diameter of the M1 segment ranges from 2 to 3 mm. Lenticulostriate-rich regions such as the M1 segment need to be accounted for when planning angioplasty.

Posterior circulation ICAD tends to affect the intradural segment of the vertebral artery and the basilar artery. The vertebral artery diameter is roughly 3–5 mm; the basilar artery diameter is 2–3 mm. Determination of the anterior inferior cerebellar artery (AICA) origin is important when planning angioplasty for basilar artery stenosis as perforator-rich regions above the AICA origin can lead to periprocedural complications.

Periprocedural Medications

Dual antiplatelet therapy with aspirin (325 mg daily) and clopidogrel (75 mg daily) is prescribed for the prevention of platelet aggregation and progression of ICAD. Although the initial results of WASID demonstrated that Warfarin had a lower 2-year stroke rate than aspirin, a randomized controlled trial evaluating 100 patients found combination therapy with aspirin and clopidogrel to be more effective. Dual antiplatelet therapy is maintained 3 months with reevaluation of the patient’s symptoms or sooner if the patient continues to be symptomatic. Aspirin and clopidogrel serum responses should be monitored and therapeutic. Patients who are found to be nonresponsive or allergic to clopidogrel can be switched to an alternative antiplatelet agent, including ticagrelor.

Intraprocedural thrombus formation is always a risk and systemic heparinization is administered during the procedure because of the risk of intraprocedural thrombus formation. A weight-based intravenous bolus of heparin aimed at an activated clotting time (ACT) of 250–300 s may limit thromboembolic complications. Administration of the 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.

Specific Technique and Key Steps

Submaximal angioplasty for ICAD tends to use undersized noncompliant balloons to allow for appropriate pressure and management while inflating the balloon ( Fig. 22.1–22.3, Video 22.1–22.3 ).

1. 
   

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

   
   
2. 
   

   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.

   
   
3. 
   

   The guide catheter is brought up into the distal ICA. The guide catheter can be brought over a select catheter and 035-inch Glidewire (Terumo).

   
   
4. 
   

   Cerebral angiography is performed to obtain a baseline set of images of the intracranial vasculature ( Video 22.1–22.3 ).

   
   
5. 
   

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

   
   
6. 
   

   Selection of the balloon should be sized to be 80% of normal vessel diameter when inflated to nominal pressures:

   
   
   
   
   1. 
      

      Noncompliant balloon (Gateway, 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 (2–3 mm) ( Fig. 22.1–22.3, Video 22.1–22.3 ).

      
      
   2. 
      

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

      
      
   3. 
      

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

   
   
7. 
   

   The patient is systemically heparinized with an ACT in the range of 250–300 s.

   
   
8. 
   

   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 ( Video 22.1–22.3 ).

   
   
9. 
   

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

Device Selection

In the authors’ and editors’ practice, the following are common set-ups and devices used for intracranial angioplasty:

• 
  

  6 or 8F sheath.

  
  
• 
  

  6F guide catheter (i.e., Envoy DA XB catheter, Codman Neuro; Benchmark, Penumbra).

  
  
• 
  

  0.035-inch angled Glidewire.

  
  
• 
  

  Intermediate 5F-diagnostic catheter (Vitek, Cook).

  
  
• 
  

  Synchro 2 microwire (Stryker).

  
  
• 
  

  Noncompliant balloon (i.e., Gateway or Sprinter balloon).

  
  
• 
  

  Continuous heparinized flush.