Feb 27, 2024
Authors:
Sebouh Bazikian - MS4 at Keck School of Medicine of University of Southern California
Gowri Gowda - PGY1 at the University of California Davis Integrated Vascular Surgery Program
Steven Maximus- Vascular surgery attending at the University of California Davis, Director of the Aortic Center
Resources:
Rutherford’s 10th Edition Chapters: 88, 89, and 91
Houston Methodist CEA Dissection Video:
Part 1: https://www.youtube.com/watch?v=wZ8PzhwmSXQ
Part 2: https://www.youtube.com/watch?v=E_wWpRKBy4w
Outline:
1. Etiology of Carotid Artery Stenosis
Risk factors: advanced age, tobacco use, hypertension, diabetes.
Atherosclerosis as the primary cause.
Development of Atherosclerotic Disease and Plaque Formation
LDL accumulation in arterial walls initiating plaque formation.
Inflammatory response, macrophage transformation, smooth muscle cell proliferation.
Role of turbulent blood flow at carotid bifurcation in plaque development.
Clinical Features of Carotid Artery Stenosis
Asymptomatic nature in many patients.
Symptomatic presentation: Transient ischemic attacks, amaurosis fugax, contralateral weakness/sensory deficit.
Carotid bruit as a physical finding, limitations in diagnosis.
Importance of Evaluating CAS
Assessing stenosis severity and stroke risk.
Revascularization benefits dependent on stenosis severity.
Classification of Stenosis Levels
Clinically significant stenosis: ≥ 50% narrowing.
Moderate stenosis: 50%–69% narrowing.
Severe stenosis: 70%–99% narrowing.
Stroke Risk Associated with Carotid Stenosis
Annual stroke rate: ~1% for 50-69% stenosis, 2-3% for 70-99% stenosis.
Diagnosis and Screening
No population-level screening recommendation.
Screening for high-risk individuals as per SVS guidelines.
Carotid Duplex Ultrasound as primary diagnostic tool.
Additional tools: CT angiography, Magnetic Resonance Angiography.
Handling of <50% stenosis cases.
Imaging Modalities
Ultrasound: Noninvasive, cost-effective, potential overestimation of stenosis.
CTA: Fast, high resolution, contrast exposure risks.
MRA: Contrast-free plaque analysis, possible overestimation of stenosis.
Angiography: Gold standard, expensive, stroke risk.
Assessing Degree of Stenosis via CDUS
Parameters for 50-69% stenosis: Peak Systolic Velocity (PSV) 125-229 cm/sec, End Diastolic Velocity (EDV) 40-100 cm/sec, Internal/Common Carotid peak systolic velocity Ratio 2-4.
Parameters for 70-99% stenosis: PSV ≥ 230 cm/sec, EDV > 100 cm/sec, Internal/Common Carotid peak systolic velocity Ratio > 4.
Revascularization Criteria
Symptomatic Patients: 50-69% or 70-99% stenosis, life expectancy at least three or two years, respectively.
Asymptomatic Patients: <50% stenosis, no revascularization; 50-69% stenosis, follow-up and surveillance; >70% stenosis, considering life expectancy.
Surgical Indications and Contraindications
Indications: symptomatic patients, life expectancy considerations.
Contraindications: Stenosis <50%, severe comorbidities, 100% occlusion.
Medical Management for All CAS Patients
Lifestyle changes, high-intensity statin therapy, antiplatelet therapy.
Decision Factors for Surgical Approaches
TCAR, stenting, endarterectomy: situational preferences.
Carotid Endarterectomy: Surgical Procedure
Incision along anterior border of sternocleidomastoid muscle.
Electrocautery through platysma muscle and subcutaneous tissues.
Protecting the great auricular nerve, dividing the external jugular vein.
Retracting sternocleidomastoid muscle, exposing carotid sheath.
Dissecting internal jugular vein, ligating facial vein.
Avoiding injury to the vagus nerve, dissecting the common carotid artery.
Identifying and mobilizing the hypoglossal nerve, addressing the external carotid artery.
Extending dissection from common carotid artery to beyond the internal and external carotid bifurcation.
Longitudinal arteriotomy, plaque removal using a Freer elevator.
Ensuring a smooth transition between endarterectomized artery and normal distal extent.
Patch angioplasty for arteriotomy closure, sequential clamp release for de-airing.
Neuromonitoring and Plaque Removal
Neuromonitoring methods: EEG, SSEPs, TCD, cerebral oximetry, awake patient monitoring.
Shunting and Vessel Closure
Shunting indications: neurological status changes, EEG alterations.
Carotid stump pressure measurement.
Postoperative Complications and Management
Common complications: stroke, hyperperfusion syndrome, myocardial infarction, cervical hematoma, nerve injuries, infection.
Managing hyperperfusion syndrome: blood pressure control, antiepileptic drugs.
Cranial nerve injuries:
Hypoglossal Nerve (CN XII): Injury leads to tongue deviation towards the injured side.
Glossopharyngeal Nerve (CN IX): Injury results in swallowing difficulties and aspiration risk.
Vagus Nerve (CN X): Injury causes hoarseness due to laryngeal muscle involvement.
Marginal Mandibular Branch of Facial Nerve: Injury leads to ipsilateral lip droop.
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