Perioperative management - Open TEA of the left carotid bifurcation with eversion endarterectomy (EEA) of the internal carotid artery for symptomatic carotid bifurcation stenosis

1. Asymptomatic carotid stenosis

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

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

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

• progressive stenosis under optimal medical therapy including smoking cessation
• contralateral internal carotid artery occlusion
• contralateral symptomatic stenosis with ipsilateral high-grade asymptomatic stenosis
• statin intolerance
• adverse morphology of the carotid plaque, e.g. floating thrombi or ulcers
• intraplaque haemorrhage on MRI
• microembolism on transcranial Doppler ultrasonography
• silent infarction on CT or MRI
• reduced cerebrovascular reserve

2. Symptomatic carotid stenosis

Symptomatic carotid stenosis should undergo surgery from a degree of stenosis of 50%, 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-embolisation and increased risk of stroke)
• in crescendo TIA (recurrent carotid-associated TIAs at ever shorter intervals) as emergency surgery for secondary prevention
• in manifest stroke in stable patients with regressive neurological symptoms as early as possible; preoperative MRI detection of intracranial barrier disruption and progressive haemorrhage is mandatory; interdisciplinary indication!

Staging of carotid stenosis

• 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 dental regions
• Severe cardiopulmonary comorbidity
• Severe neurological deficit requiring nursing care

Medical history

• Vascular risk factors: smoking, arterial hypertension, dyslipidemia, diabetes mellitus

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 carotid territory (internal carotid artery) are:

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

→ Amaurosis fugax (transient unilateral blindness: ophthalmic 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 coronary heart disease requiring treatment

Colour flow Doppler imaging

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

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

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

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

Plaque parameters with unfavourable prognosis:

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

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

CT or MRI of the brain

• In symptomatic patients, parenchymal imaging prior to elective revascularisation
• 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 dual therapy, 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 and nerve damage, e.g. due to patient positioning
• Keloids

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 dyspnoea; angular palsy; shoulder elevation weakness
• Secondary bleeding, haematoma-induced tracheal compression, emergency surgical decompression
• Injury to the carotid body (glomus caroticum): arrhythmia, blood pressure fluctuation
• Cardiopulmonary complications: myocardial infarction, pneumonia, pulmonary embolism
• Hyperperfusion syndrome: seizures, neurological deficits, migraine-like headaches, cerebral oedema/haemorrhage
• Suture aneurysm → re-operation
• Intraoperative angiography: contrast-induced renal failure

Risks specific to surgery under regional anaesthesia (cervical plexus)

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