Perioperative management - Left carotid bifurcation eversion endarterectomy (EEA) in symptomatic carotid bifurcation stenosis – Vascular Surgery

1. Asymptomatic carotid stenosis

Stenosis is classified as asymptomatic if there have been no stenosis-associated symptoms within the prior six months.

According to current guidelines, surgical desobliteration in asymptomatic carotid stenosis of least 60% may be recommended, provided that the perioperative risk of stroke is <3%. Moreover, patients should have a life expectancy of more than 5 years.

In asymptomatic carotid stenosis, patients with the following particular risk factors benefit from invasive treatment:

• Progressive stenosis under optimized medication including smoking cessation
• Occlusion of the contralateral internal carotid artery
• Contralateral symptomatic stenosis and ipsilateral high-grade asymptomatic stenosis
• Statin intolerance
• Adverse morphology of the carotid plaque, e.g., floating thrombi or ulcers
• Bleeding into plaque on MRI
• Microembolism in transcranial Doppler ultrasonography
• Silent infarction on CT or MR imaging
• Reduced cerebrovascular reserve

2.  Symptomatic carotid stenosis

Symptomatic carotid stenosis with luminal narrowing of 50% or more should undergo surgery, with a perioperative risk of stroke of <6%.

Timing

• In TIA or non-disabling stroke, if possible within the first 2 weeks (ruptured plaque with increased rate of re-embolization and increased risk of stroke)
• In crescendo TIA (recurrent carotid-associated TIAs in ever shorter intervals) as emergent surgery for secondary prevention
• In stable patients with regressive neurological symptoms of manifest stroke as early as possible; preoperative MRI detection of impaired intracranial barrier and progressive bleeding mandatory; interdisciplinary indication!

Carotid stenosis staging

• EEA is not suited for long stenosis of the internal carotid artery reaching far downstream; it is reserved for short stenosis close to the ICA origin
• Severe transmural calcification of the carotid bifurcation extending into the cranium
• History of neck dissection with radiotherapy
• Rarely morbid obesity with loss of neck contour
• Local florid infection, including ENT and dentistry
• Major cardiopulmonary comorbidity
• Severe neurological deficit requiring nursing care

Medical history

• Vascular risk factors Smoking, arterial hypertension, dyslipidemia, diabetes

Clinical neurological examination

• >90% of stenoses and occlusions of supraaortic vessels (ICA, vertebral artery, etc.) often remain clinically asymptomatic and are incidental findings during screening examinations or preoperative imaging studies
• Symptoms of a lesion in the vessels supplying the brain depend on the vessel involved, the course over time, and the prevailing collateral blood supply (e.g., via the cerebral arterial circle)
• Typical symptoms of impaired blood flow in the region supplied by the carotid artery (internal carotid artery) are:

         → Motor or sensory hemisyndrome (e.g. "hemiplegia")

         → Amaurosis fugax (transient unilateral blindness: opthalmic artery)

         → Cortical dysfunction (language, visuospatial perception)

         → Rather atypical: homonymous bilateral visual field impairment 

• Important: Carotid artery auscultation is inadequate for stenosis detection!

Cardiology examination

• 30% of patients present with CHD requiring treatment

Color flow Doppler imaging

Ultrasonography of the extracranial vessels supplying the brain should always study all vessels in both the transverse and axial plane:

• Common carotid artery from proximal to carotid bifurcation
• Carotid bifurcation with the posterolateral origin of the ICA
• External carotid artery
• Segments V1 to V3 of vertebral artery
• Subclavian artery and axillary artery

Search for hemodynamically relevant plaques and their morphological description ( B-mode):

• Hyperechoic versus hypoechoic
• Homogeneous versus inhomogeneous
• Smooth versus irregular contour

Plaque parameters with unfavorable prognosis:

• Hypoechoic internal plaque structure
• Extended plaque >1 cm
• Plaque diameter >4 mm
• Axial pulsation of the distal plaque

By international agreement, stenoses should be quantified according to the NASCET criteria.

Contrast-enhanced MR angiography or alternatively, CT angiography

• Validation of the findings or for treatment planning
• Assessment of intracranial vessels and possible parenchymal lesions (prior cerebral infarctions)

Digital subtraction angiography (DSA) of the arteries supplying the brain (rarely required)

• Only if the noninvasive procedures have proved inconclusive resulting in therapeutic consequences
• Example: stenotic kinking not evident on MRI or CT scan

CT or MRI of the brain

• In symptomatic patients, parenchymal imaging prior to elective revascularization
• In asymptomatic patients, such imaging can provide important additional insight, e.g., evidence of clinically silent cerebral infarction

Chest x-ray

Laboratory panels

• Blood count
• Electrolytes
• Coagulation
• Kidney function parameters
• Liver function parameters
• Blood lipids
• Blood group

In all patients with arteriosclerotic carotid stenosis, other sequelae of arteriosclerosis (coronary artery disease [CAD], peripheral arterial occlusive disease [PAOD]) should be assessed!

• Mark affected side
• Have patient fast 2–6 hours as per department protocol
• Continue platelet inhibitors; in combined anticoagulation, decide case-by-case based on cardiac risk profile

General surgical risks

• Major bleeding, blood transfusions, transmission of hepatitis/HIV through allogeneic blood transfusions
• Allergy/intolerance
• Wound infection
• Thrombosis/embolism
• Skin/vascular/nerve damage, e.g. due to patient positioning
• Keloid

Procedure-specific risks

• Cerebrovascular disorder/stroke
• Impaired blood supply to the eyes and even blindness
• Injury to cervical nerves: Hoarseness; loss of voice; dysphagia and dyspnea; angular palsy; shoulder elevation palsy
• Secondary bleeding, hematoma-induced tracheal compression, emergency surgical decompression
• Injury to carotid body (glomus caroticum): arrhythmia, blood pressure fluctuation
• Cardiopulmonary complications: myocardial infarction, pneumonia, pulmonary embolism
• Hyperperfusion syndrome:  seizures, neurological deficits, migraine-like headaches, cerebral edema/bleeding
• Suture aneurysm → re-operation
• Intraoperative angiography: contrast-induced renal failure

Risks specific to surgery with regional anesthesia (cervical plexus)

• Horner syndrome (drooping eyelid)
• Sensation of facial warmth, hoarseness, dyspnea
• Numbness of adjacent structures: brachial plexus, cervical spinal cord