Carotid Endarterectomy

Article Author:
Mary DaCosta
Article Author (Archived):
Prasanna Tadi
Article Editor:
Scott Surowiec
Updated:
3/22/2019 12:59:46 AM
PubMed Link:
Carotid Endarterectomy

Introduction

A build-up of plaque in the carotid artery can lead to atherosclerosis, narrowing of the artery, stenosis, and subsequent carotid artery disease. Carotid artery disease increases a person’s risk for cerebrovascular disease or stroke. This disease can be asymptomatic or symptomatic. Carotid endarterectomy (CEA) is a surgery performed to decrease the risk of stroke. The procedure entails removing plaque from the common carotid artery and internal carotid artery to improve blood flow and remove embolic material. Carotid artery reconstructions began in the early 1950s, and techniques for carotid endarterectomy procedures, as well as indications to perform them, have evolved.[1][2][3][4]

Anatomy

Within the superior mediastinum, the arch of the aorta can be found at the level of the sternal angle. Three large vessels originate from the aorta. This includes the brachiocephalic trunk, the left common carotid artery, and left subclavian artery.  On the right side, the common carotid artery stems off as the first branch the brachiocephalic trunk. Both the left and right common carotids will bifurcate into an internal and external carotid artery. This division occurs around the fourth cervical vertebrae (C4) along the superior border of the thyroid cartilage. There is a deep cervical fascia that forms the carotid sheath. This surrounds the carotid arteries, internal jugular vein, and vagus nerve. They are found medially to the sternocleidomastoid muscle. The internal carotid artery will continue into the skull to form part of the Circle of Willis and supply blood to the brain and eyes. Branches of the external carotid artery supply blood to the neck and face.

Indications

In 1987 the North American Symptomatic Carotid Endarterectomy Trials (NASCET) began. Patients with moderate carotid stenosis (less than 70%) and severe carotid stenosis (greater than 70%) were randomly assigned to treatment groups, which included antithrombotic medication for a majority of patients. The study found that the benefit of surgery was great for those who had severe carotid stenosis, and patients with less than 50% stenosis were found to have no benefit. Patients who have 50% or more narrowing of the carotid artery and history of ipsilateral stroke or TIA are recommended to have carotid endarterectomy surgery.  Symptoms of TIA can include amaurosis fugax, a painless temporary loss of vision in one or both eyes, hemiparesis, and speech loss episode.

Asymptomatic patients with 70% or more narrowing, also are encouraged to undertake the surgery. In the Asymptomatic Carotid Artery Stenosis (ACAS) trials for endarterectomy, it was shown that after the procedure there is a significant 5-year reduction in stroke risk in asymptomatic patients.  As medical therapy has improved since the 1980s, the CREST-2 trial is currently underway. The trial will provide data about best medical therapy versus surgery in patients with asymptomatic, high grade internal carotid stenosis.

It is possible to screen asymptomatic patients with the use of carotid duplex ultrasonography (CDU). It can assess the degree of carotid stenosis. The severity of the obstruction correlates to carotid velocity. Inaccuracies can be shown if there are blood vessel kinks and bends which may cause elevated velocities. Although it is a great tool for detecting hemodynamically significant stenosis, it has relatively low specificity for those patients with 50% to 60% stenosis. Other forms of screening include computed tomography angiography (CTA), and contrast-enhanced magnetic resonance angiography (CE-MRA). They help to assess other variables that can impact an individuals risk including plaque morphology, intracranial collateralization, and brain perfusion. CTA or CE-MRA information can be used alongside CDU to help put into perspective a patient's need for surgery. [5][6][7][8]

For patients with symptomatic carotid occlusion (50-99%), if carotid endarterectomy was done within 2 weeks of symptoms, the number needed to treat for preventing one stroke is 5. The number needed to treat increases to 125 if it has done more than 2 weeks of symptoms or stroke onset. CEA is beneficial if the symptoms are non-disabling, no tandem stenoses, high-grade stenosis. CEA can be deferred if the stroke is too big, contralateral carotid occlusion, hemodynamic instability, and contralateral laryngeal palsy is a relative contraindication. There is more myocardial infarction associated with CEA. 

Carotid artery stenting (CAS) is preferred in symptomatic carotid occlusion (50-99%) with multiple comorbidities, tracheostomy, patients with prior neck radiation or dissection. Usually, there is an increased risk of stroke after the CAS. Due to the advancement of the stents and technique, CAS is comparable to CEA in most instances. CREST-2 study is ongoing and will shed more light in this important area. 

Contraindications

Symptomatic patients who are very ill and unable to undergo surgery may be candidates for carotid angioplasty and stenting (CAS).  The stent, a small, flexible, mesh-like tube is inserted into the artery under local anesthesia. The tube is then expanded to move plaque deposit out of the way and allow for more blood flow through the area. It was found from the carotid revascularization endarterectomy versus stenting Trials (CREST) that CEA and CAS did not yield significant differences when considering postoperative complications like restenosis, myocardial infarction, periprocedural stroke, ipsilateral stroke, and/or death. However, differences in the risk of stroke or death were higher in patients that underwent CAS. Other considerations for stenting is if the patient is at high risk for general anesthesia complications.

Patients who have undergone neck radiotherapy, inducing stenosis, are at higher risk of developing temporary cranial nerve injury during endarterectomy, and late cerebrovascular events and restenosis following angioplasty and stenting. Endarterectomy is more challenging because these patients tend to have more diffuse plaques, as well as adhesions, scar tissue, and wound complications if prior radical neck dissection is done.

Women are at higher risk of developing complications because they have smaller carotid arteries. A study using multivariate regression compared the diameters of the common and internal carotid arteries in men and women based on age, weight, height, body mass index (BMI), neck circumference, body surface area, neck length, and blood pressure. Even with controlling for confounding variables such as blood pressure, body size, neck size, and age, women were found to have smaller arteries and a slightly smaller left common carotid when compared to the right. Women with asymptomatic carotid stenosis may benefit less from carotid endarterectomy surgery and could experience early complications from the surgery.

Preparation

A patient undergoing carotid endarterectomy should be on antiplatelet therapy (unless contraindicated) before the surgery. For this procedure, general anesthesia or local anesthesia may be used. For local anesthesia, the patient can be awake but sedated. They will feel numbness only at the site of the surgery. The patient should be draped and sterilized at the neck including the jaw and earlobe.

Technique

There are two main surgical techniques for carotid endarterectomy: the classical/conventional method and the eversion method.

Classical/Conventional Method

The surgeon makes an incision alongside the medial aspect of the sternocleidomastoid muscle, cutting through fat, the platysma muscle, and eventually reaching the carotid sheath. After carefully removing part of the sheath, the carotid arteries are exposed. The internal carotid artery is clamped down to temporarily stop blood flow. The surgeon will open a long the length of the internal carotid artery, as much needed to find the plaque. Before removing the plaque, the clamps are taken off the artery, and a flexible tube is placed to shunt blood around the endarterectomy site. After the blockage is removed, the artery is sewn closed with a patch that will widen the vessel. There are different options for patches, including the patient's vein, bovine patch, or artificial patch (Dacron). After the patch is sewn on, it is important to confirm satisfactory blood flow with ultrasound Doppler or angiography.

Eversion Method

With the eversion method, the internal carotid artery is cut obliquely at the base where it originates from the bifurcation of the common carotid artery.  It is shortened and partially everted. The plaque is divided and removed. Sutures then close the artery. The benefits of this include no need for patch closure, the operation time and carotid clamping time is also reduced.

Complications

Complications during and after surgery are dependent on various factors, such as surgeon skill and technique, patient’s risk factors, management before or after surgery.

Complications of CEA include:

Major complications

  • Myocardial Infarction
  • Hyperperfusion syndrome
  • Nerve Injury, particularly the cranial nerves; hypoglossal, vagus, glossopharyngeal, trigeminal, and facial nerves
  • Perioperative stroke
  • Death

Minor Complications

  • Restenosis
  • Transient ischemic attack
  • Bleeding
  • Cervical hematoma
  • Infection

Clinical Significance

Carotid endarterectomy is a stroke-preventing procedure that helps improve patient health and subsequent quality of life. Drug therapy alone, (in most cases) is not enough for patients with moderate to severe carotid stenosis. Risks associated with the surgery, but usually, the benefits outweigh them.[9][10]

Enhancing Healthcare Team Outcomes

Patients with a  mini-stroke (TIA) or evidence of carotid artery atherosclerosis are frequently seen by the primary care provider and nurse practitioner. If workup reveals narrowing of the carotid artery, the patient should be referred to the neurologist and vascular surgeon. Carotid endarterectomy has been proven to reduce the risk of stroke. The procedure itself can cause a stroke and hence, one should always educate the patient on potential complications of the procedure. Overall, the majority of patients who undergo the procedure have no complications. However, the primary care provider should encourage the patient to eliminate the risk factors for stroke like discontinuing smoking, maintaining a healthy weight and lowering levels of cholesterol. Regular exercise is highly recommended.[11]


References

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[6] Lamanna A,Maingard J,Barras CD,Kok HK,Handelman G,Chandra RV,Thijs V,Brooks DM,Asadi H, Carotid artery stenting: Current state of evidence and future directions. Acta neurologica Scandinavica. 2019 Jan 4;     [PubMed PMID: 30613950]
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