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

• ITN
• Regional anesthesia (cervical plexus) in cooperative patients; not in extremely high carotid lesions

Supine position with moderate reclination of the head (position padding under the shoulder blades) and rotation to the contralateral side. Both arms are adducted.

The positioning must be carried out with particular care, as especially older patients exhibit variably pronounced osteochondrosis of the cervical spine, which can lead to vertebral damages in case of overly forced positioning. With stable blood pressure, positioning can be done in 10° anti-Trendelenburg position. This improves the exposure of the carotid bifurcation, venous pressure and venous bleeding are somewhat reduced.

The surgeon stands on the side to be operated on, opposite him the 1st assistant as well as towards the feet the OR specialist. Towards the head next to the surgeon stands the 2nd assistant. Instead of the 2nd assistant, the upper wound angle can be equipped with a retractor (Caution: pressure injuries to branches of the facial nerve!).

In addition to the usual vascular instrumentation:

• Shunt tubes of different diameters
• Retractors (e.g., Martin retractor)
• Wound retractors
• Special vascular clamps (e.g., Gregory soft carotid clamps)
• if necessary, equipment for intraoperative neuromonitoring 

Postoperative Analgesia

Follow the link here to PROSPECT (Procedure Specific Postoperative Pain Management) and to the current guideline Treatment of acute perioperative and posttraumatic pain.

Medical Follow-up Care

• Monitoring in Intermediate Care for 24 hours
• Inspection of the surgical site: neck circumference, wound area, and drainage
• Circulatory monitoring
• Laboratory checks
• Neurological checks: on the day of surgery postoperatively as well as on the 2nd-3rd postoperative day.
• Removal of Redon drainage on the following day if < 50 ml secretion; Pull without suction to avoid a lesion of the N. vagus
• Duplex check from the 3rd postoperative day.
• ASA 100 1x1, if necessary in combination with Clopidogrel
• Discharge usually possible from the 5th postoperative day

Thrombosis Prophylaxis

•  In general, low molecular weight heparin s.c. perioperatively every 24 h    

Mobilization

• Normal mobilization possible from the 1st postoperative day

Physiotherapy

•  Generally dispensable

Diet Build-up

• Drinking 6 hours and small meal  8 hours postoperatively

Bowel Regulation

•  Generally dispensable

Inability to Work

• 2 – 4 weeks

Follow-up: Duplex sonography after 4-6 weeks, after ½ year and then annually. Minimize risk factors!