Perioperative management - Open TEA of the left carotid bifurcation with patch angioplasty and temporary intraluminal shunt

1. Asymptomatic Carotid Stenosis

A stenosis is classified as asymptomatic if no stenosis-associated symptoms have occurred in the past six months.

According to current guidelines, surgical desobliteration can be recommended for a 60% asymptomatic carotid stenosis, provided that the perioperative stroke risk < 3 %. Furthermore, patients should have a life expectancy of over 5 years.

In asymptomatic carotid stenosis, patients with the following risk factors particularly benefit from invasive therapy:

• progressive stenoses under optimal medical therapy including nicotine abstinence
• contralateral internal carotid occlusion
• contralateral symptomatic, ipsilateral high-grade asymptomatic stenosis
• statin intolerance
• unfavorable morphology of the carotid plaque, e.g., floating thrombi or ulcers
• hemorrhages in the plaque on MRI
• microembolism in transcranial Doppler ultrasound
• silent infarcts on CT or MRI
• reduced cerebrovascular reserve

2. Symptomatic Carotid Stenosis

Symptomatic carotid stenoses should be operated on from a stenosis degree of 50 %, the perioperative stroke risk should be < 6 %.

Timing:

• in TIA or non-disabling stroke as soon as possible within the first 2 weeks (ruptured plaque with increased re-embolization rate and increased stroke risk)
• in crescendo TIA (repeated carotid-associated TIAs in shortening time intervals) as emergency secondary preventive surgery
• in manifest stroke in stable patients with regressing neurological symptoms as early as possible; preoperative MRI detection of intracranial barrier disruptions and progressive hemorrhages required; interdisciplinary indication!

Staging of Carotid Stenosis

• severe, long-segment transmural calcifications of the carotid bifurcation extending to intracranial
• Status post neck dissection with radiation
• rarely morbid obesity with loss of the neck silhouette
• local florid infections, also in ENT and dental areas
• severe cardiopulmonary comorbidities
• severe neurological deficit with need for care

Medical History

• vascular risk factors: smoking, arterial hypertension, lipid metabolism disorders, diabetes mellitus

Clinical-Neurological Examination

• > 90 % of stenoses and occlusions of supra-aortic vessels (ICA, vertebral artery, etc.) often remain clinically asymptomatic and are discovered during screening examinations or preoperative imaging
• Symptoms of a lesion of the brain-supplying vessels depend on the affected vessel, the temporal course, and the predominant collateralization (e.g., via the Circle of Willis)
• typical symptoms of a disturbance in the carotid territory (internal carotid artery) are:

         → motor or sensory hemisymptoms (e.g., "hemiparesis")

         → Amaurosis fugax (transient unilateral blindness: ophthalmic artery)

         → cortical functional disorders (speech, visual-spatial perception)

         → rather atypical: homonymous bilateral visual field defects 

• Important: Auscultation of the carotid artery is not suitable for stenosis detection!

Cardiological Examination

• 30 % of patients have treatable CAD

Color-Coded Duplex Sonography

In the ultrasound examination of the extracranial brain-supplying vessels, all vessels should always be assessed in transverse and longitudinal sections:

• common carotid artery from proximal to the carotid bifurcation
• carotid bifurcation with dorsolateral branching internal carotid artery
• external carotid artery
• vertebral artery in segments V1 to V3
• subclavian artery and axillary artery

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

• echogenic versus hypoechoic
• homogeneous versus inhomogeneous
• smooth versus irregularly configured

Prognostically unfavorable plaque parameters:

• hypoechoic plaque internal structure
• long-segment plaque > 1 cm
• plaque diameter > 4 mm
• longitudinal pulsation of the plaque distally

According to international agreement, stenosis quantification should be performed according to the NASCET criteria.

Contrast-Enhanced MR Angiography or alternatively CT Angiography

• Validation of findings or for therapy planning
• Evaluation of intracranial vessels and possible parenchymal damage (previous cerebral infarcts)

Digital Subtraction Angiography (DSA) of the brain-supplying arteries (rarely required)

• only if no conclusive statement is possible with noninvasive methods and a therapeutic consequence results
• Example: kinking stenosis not visible on MRI or CT

CT or MRI of the Brain

• in symptomatic patients, parenchymal imaging before planned revascularization
• in asymptomatic patients, such imaging can provide important additional information, e.g., evidence of a clinically silent cerebral infarct

Chest X-ray Examination

Laboratory

• CBC
• Electrolytes
• Coagulation
• Retention values
• Liver enzymes
• Blood lipids
• Blood group

In all patients with atherosclerotic carotid stenoses, further sequelae of atherosclerosis (coronary artery disease [CAD], peripheral arterial occlusive disease [PAOD]) should be assessed!

• Mark the side
• Fasting 2 – 6 hours depending on clinic standard
• Continue antiplatelet agents; for dual therapy, individual decision based on cardiac risk profile

General Surgical Risks

• Severe bleeding, blood transfusions, transmission of Hepatitis/HIV through blood products
• Allergy/Intolerance
• Wound infection
• Thrombosis/Embolism
• Skin, vascular, nerve damage e.g. due to positioning
• Keloids

Specific Surgical Risks

• Cerebral perfusion disorders/Stroke
• Perfusion disorders of the eyes up to blindness
• Injury to neck nerves: Hoarseness, voice loss, swallowing and breathing disorders, corner of mouth paresis, shoulder elevation weakness
• Postoperative bleeding, hematoma-induced tracheal compression, emergency surgical relief
• Injury to carotid body: Arrhythmias, blood pressure fluctuations
• Cardiopulmonary complications: Myocardial infarction, pneumonia, pulmonary embolism
• Hyperperfusion syndrome: Seizures, neurological deficits, migraine-like headaches, cerebral edema, hemorrhage
• Suture aneurysm → Re-OP
• Intraoperative angiography: Contrast-induced renal insufficiency

Specific Risks in Surgery under Regional Anesthesia (Cervical Plexus)

• Horner's Syndrome (Drooping of the eyelid)
• Warm sensation in the face, hoarseness, breathing difficulties
• Co-anesthesia of adjacent structures: Brachial plexus, cervical spinal cord