Overview
Definition:
Carotid Artery Stenting (CAS) is an endovascular procedure used to open narrowed or blocked carotid arteries, most commonly due to atherosclerotic plaque, thereby restoring blood flow to the brain and reducing the risk of ischemic stroke
It involves inserting a stent, a small expandable mesh tube, into the artery to keep it open.
Epidemiology:
Carotid artery stenosis (CAS) is a significant cause of ischemic stroke, accounting for approximately 10-20% of all strokes
The prevalence of symptomatic severe (≥50%) carotid stenosis is estimated to be around 1-5% in the general population and increases with age
Asymptomatic severe CAS is found in 5-10% of individuals over 70.
Clinical Significance:
Effectively managing carotid artery stenosis is crucial for stroke prevention, a major cause of long-term disability and mortality worldwide
CAS offers an alternative or adjunctive treatment to carotid endarterectomy (CEA), particularly for patients with specific anatomical challenges or high surgical risk
Proper patient selection and procedural setup are paramount for optimal outcomes.
Indications
Symptomatic Stenosis:
CAS is indicated in patients with symptomatic severe (≥70%) internal carotid artery (ICA) stenosis, especially those with recent transient ischemic attack (TIA) or non-disabling ischemic stroke attributable to the stenosis
Moderate (50-69%) symptomatic stenosis may be considered in select high-risk patients after multidisciplinary consensus.
Asymptomatic Stenosis:
CAS for asymptomatic severe (≥70%) ICA stenosis is controversial
Indications include patients with significant comorbidities making CEA high-risk, contraindications to CEA, or specific imaging findings suggestive of plaque vulnerability and increased stroke risk.
Alternative To Cea:
CAS is indicated as an alternative to CEA in patients who are poor surgical candidates due to advanced age, comorbidities (e.g., severe COPD, cardiac disease, previous neck surgery or radiation), or unfavorable anatomy (e.g., high carotid bifurcation, contralateral carotid occlusion).
Restenosis After Cea:
Recurrent stenosis after previous CEA (in-stent restenosis or pseudoaneurysm) can be an indication for CAS if symptoms recur or significant stenosis is present.
Contraindications:
Absolute contraindications include severe ipsilateral neurological deficits with poor prognosis, severe medical comorbidities precluding stroke from surgery, and life expectancy < 1 year
Relative contraindications include severe intracranial occlusive disease or severe cerebral atrophy.
Preoperative Preparation
Patient Assessment:
Comprehensive cardiovascular and neurological assessment is essential
Assess comorbidities like hypertension, diabetes, hyperlipidemia, and renal dysfunction
Evaluate previous stroke or TIA, its severity, and neurological deficits.
Imaging Studies:
High-resolution imaging of the carotid arteries is mandatory
This includes duplex ultrasonography (carotid US), computed tomography angiography (CTA), or magnetic resonance angiography (MRA) to confirm stenosis severity, plaque characteristics, and assess intracranial circulation
Invasive angiography may be performed if non-invasive imaging is inconclusive.
Antiplatelet Therapy:
Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel (or ticagrelor/prasugrel) is typically initiated at least 48-72 hours prior to the procedure, if not contraindicated, and continued post-procedure for a specified duration based on stroke risk and stenting approach.
Neurological Monitoring:
Establish baseline neurological status
Intraprocedural neurological monitoring, including patient alertness checks and potential use of electroencephalography (EEG) or transcranial Doppler (TCD), is crucial.
Anesthesia Plan:
The procedure can be performed under local anesthesia with sedation or general anesthesia, depending on patient comfort, procedural complexity, and institutional preference
Anesthesia selection should facilitate close neurological monitoring.
Procedural Setup And Technique
Access Site:
Vascular access is typically achieved via percutaneous femoral artery puncture using ultrasound and fluoroscopic guidance
Sheath placement in the common femoral artery is performed using standard Seldinger technique.
Guidewire And Catheter Selection:
A stiff guidewire is advanced through the sheath into the aorta
Angiographic catheters (e.g., pigtail, multipurpose) are used to visualize the aorta and origins of the great vessels
Specific catheters designed for carotid access (e.g., vertebral, MPA) or glide catheters may be used to navigate into the common carotid artery.
Distal Protection Devices:
Cerebral protection devices (CPDs) are a critical component of CAS setup to minimize embolization of plaque debris to the brain
These include distal embolic protection filters deployed distal to the stenosis or flow reversal systems
The choice depends on lesion characteristics and operator preference.
Balloon Angioplasty And Stent Deployment:
Once the lesion is crossed and CPD is in place, a balloon catheter is advanced across the stenosis for pre-dilation, if necessary
The stent is then deployed across the lesion, ensuring adequate coverage
Post-dilation with a balloon may be performed to ensure proper stent expansion.
Angiographic Confirmation:
Post-deployment angiography is performed to assess stent apposition, lumen patency, and absence of significant residual stenosis or dissections
The CPD is carefully retrieved once satisfactory results are confirmed.
Closure Device:
Vascular closure devices (e.g., collagen plug, suture-based devices) are used to achieve hemostasis at the femoral access site.
Complications
Neurological Complications:
Stroke (ischemic or hemorrhagic) is the most feared complication, occurring in 1-3% for symptomatic patients
TIA, amaurosis fugax, and cranial nerve palsies (e.g., hypoglossal, recurrent laryngeal) can also occur.
Vascular Access Site Complications:
Hematoma, pseudoaneurysm, arteriovenous fistula, bleeding, or infection at the femoral access site are common
Iliac artery dissection or occlusion can also occur.
Cardiac Complications:
Myocardial infarction, arrhythmias (especially bradycardia or hypotension during instrumentation), and contrast-induced nephropathy can occur.
Stent Related Complications:
Stent thrombosis, in-stent restenosis, and stent fracture are late complications
Dissection or perforation of the carotid artery can occur during stent deployment.
Key Points
Exam Focus:
Understand the NASCET and ECST trial findings for indications of CEA vs
CAS
Recognize the criteria for symptomatic vs
asymptomatic stenosis
Differentiate between indications for stenting and endarterectomy based on patient anatomy and comorbidities.
Clinical Pearls:
Pre-operative antiplatelet therapy is crucial
Meticulous technique with proper distal protection is vital to reduce embolic risk
Close neurological monitoring during and after the procedure is non-negotiable
Multidisciplinary team approach (neurology, cardiology, surgery, radiology) is essential for optimal patient selection and management.
Common Mistakes:
Failure to adequately assess contraindications
Inadequate pre-procedure antiplatelet regimen
Incorrect placement or ineffective use of cerebral protection devices
Incomplete angiographic assessment post-stenting
Delayed neurological assessment post-procedure.