General Description

The long-term (10-year) follow-up results of the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) were reported in 2013. Restenosis occurred or revascularization was performed in 12.2% of patients treated with carotid artery stenting (CAS) in the trial. Although restenosis is not a common occurrence, the need for revascularization in previously stent-treated patients does arise, especially if the patient becomes symptomatic. The in-stent stenosis can be the result of continued plaque rupture and rerupture versus neointimal hyperplasia over the carotid stent. Different treatment options for in-stent stenosis include balloon angioplasty with or without the placement of another stent and carotid endarterectomy. Cutting balloons can also be used for angioplasty in these cases. These balloons reportedly offer minimal plaque disruption while allowing expansion of the vessel diameter.

In the authors’ practice, a stepwise approach is preferred, starting with conventional balloon angioplasty performed under embolic protection, followed by cutting balloon or drug-eluting balloon angioplasty. The placement of a second stent is the last option because of the risk of narrowing the arterial lumen. If the stenosis is because of intimal hyperplasia, we may select an open-cell stent with a higher radial opening force (e.g., Protégé, Covidien) versus a closed-cell stent (e.g., Wallstent, Boston Scientific). The key to reducing the incidence of in-stent stenosis is achieving a good result at the time of the first CAS procedure. Balloon angioplasty for in-stent stenosis should be performed with either a proximal or distal protection device depending on whether the stenosis can be crossed.

Indications

The indications for revascularization of in-stent stenosis include a symptomatic patient with > 70% in-stent stenosis. Symptomatic patients with lower degrees of stenosis should be investigated for unstable plaques for which intervention may be required. Asymptomatic patients with > 80% stenosis should also be considered for intervention.

Neuroendovascular Anatomy

Please see Chapter 10 for carotid artery anatomy. Anatomical issues that should be addressed when evaluating in-stent stenosis include the location of the stenosis (mid, proximal, or distal stent). The location of the stenosis can give clues to the underlying pathology (continued plaque buildup vs. neointimal hyperplasia vs. endoleak). The stenosis should be examined for ulcerations or a smooth circumferential appearance (indicating hyperplasia). (If the plaque is ulcerated, consideration is given to the use of proximal protection instead of distal protection.) Kinking above or below the straight stented portion of the vessel can also create stenosis or turbulent areas of flow that are prone to pathology.

Periprocedural Medications

Patients should already be placed on dual antiplatelet therapy with aspirin (325 mg daily) and clopidogrel (75 mg daily) because of the previous stent treatment. Before the recurrent stenosis procedure, platelet function should be tested and within a therapeutic range in an effort prevent platelet aggregation on any exposed stent following angioplasty or possible intimal disruption that could result in the formation of an intraluminal thrombus during or after the procedure. An alternative to clopidogrel is ticagrelor (60 mg twice daily per chapter 10) in place of clopidogrel.

Systemic heparinization is administered during the procedure because of the risk of intraprocedural thrombus formation. A weight-based bolus of heparin aimed at an activated coagulation time of 250–300 seconds may limit thromboembolic complications. The administration of heparin prior to crossing the lesion may limit thrombus formation on devices positioned within the internal carotid artery (ICA). Glycoprotein IIb/IIIa inhibitors are utilized for acute thrombus formation during the procedure.

Hemodynamic instability may occur during CAS and balloon angioplasty performed for the treatment of in-stent stenosis. Bradycardia, asystole, and hypotension are the most common events. Asking the patient to perform a Valsalva maneuver (or cough) will usually reverse bradycardia. A good practice is to have a vasopressor (e.g., dopamine or phenylephrine) available, as well as atropine. We typically perform the angioplasty procedure with the patient in an awake state (i.e., conscious sedation) for accurate neurological assessment.

Specific Technique and Key Steps

1. 
   

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

   
   
2. 
   

   Depending on the arch anatomy, the guide catheter can be brought up directly over a 0.035-inch angled Glidewire or advanced over a 4–5F intermediate diagnostic catheter, such as a Vitek or Berenstein catheter (Cook). Utmost care should be taken to prevent the wire, catheter, or guide from crossing the stenotic in-stent lesion (Fig. 14.1, 14.2, Video 14.1, 14.2).

   
   
3. 
   

   Magnified working views of the carotid artery are obtained. Measurements of the degree of stenosis, length of stenosis, and diameters of the CCA and distal ICA are obtained for proper sizing of the stent.

   
   
4. 
   

   A proximal or distal protection device is selected based on operator choice. See Chapters 10 and 11 for a description of the types of protection devices. A distal protection device (a filter type of device, the Emboshield NAV6 (Abbott), was used here.

   
   
5. 
   

   The distal embolic protection device is navigated through the stenosis up to the upper cervical ICA and deployed under fluoroscopy.

   
   
6. 
   

   Under road-mapping guidance, the filter and the noncompliant balloon are advanced over the wire to the area of stenosis. Typically, a rapid exchange system is utilized.

   
   
7. 
   

   The balloon is undersized 1 mm less than the diameter of the ICA. The balloon is inflated up to the nominal pressure specified by the manufacturer (Fig. 14.1, 14.2, Video 14.1, 14.2).

   
   
8. 
   

   Angioplasty is performed. The balloon is kept inflated for 30 seconds if tolerated by the patient. If not tolerated, the balloon is inflated for only a few seconds (5–10 s) multiple times. The balloon is inflated gradually (Video 14.1, 14.2). The patient’s heart rate is monitored closely during this process.

   
   
9. 
   

   A post-angioplasty angiographic run is performed. If the dilation is adequate (excellent, < 30% residual stenosis; good, 30%–50% residual stenosis), no further treatment is needed and the balloon can be removed. If not, the balloon can be utilized for a second angioplasty or it can be removed and a stent can be deployed. We recommend covering both ends of the previous stent by at least 5 mm to prevent endoleaks (Video 14.1, 14.2).

   
   
10. 
    

    Intravascular ultrasound can be used to look for residual debris within the lumen or residual stenosis as well as stent-to-wall approximation.

    
    
11. 
    

    The distal protection device is captured and removed, typically via a separate sheath.