Carotid Endarterectomy

Last updated date: 10-Jun-2023

Originally Written in English

Carotid Endarterectomy

Overview

Plaque buildup in the carotid artery can cause atherosclerosis and stenosis, which may or may not be clinically symptomatic. This type of carotid artery disease raises the risk of cerebrovascular disease and stroke. Carotid endarterectomy (CEA) is a surgical procedure used to reduce the risk of stroke in patients who have known cerebrovascular atherosclerotic disease.

The technique involves eliminating plaque from the common and/or internal carotid arteries in order to enhance blood flow and eliminate possible embolic debris, restoring more normal cerebral blood flow. Carotid artery reconstructions first appeared in the early 1950s, and techniques for carotid endarterectomy surgeries, as well as reasons for them, have changed since then.

 

Carotid endarterectomy definition

 Carotid endarterectomy definition

Carotid endarterectomy is a surgical operation intended to lower the risk of stroke caused by carotid artery stenosis (narrowing of the internal carotid artery). The plaque develops and enlarges in the inner layer of the artery, or intima, hence the procedure's name, which basically implies removing a portion of the artery's innermost layers. Carotid stenting is an alternative technique that can minimize the risk of stroke in some people.

 

Carotid endarterectomy anatomy

Carotid endarterectomy anatomy

The major vessels, which include the innominate artery, the left common carotid artery (CCA), and the subclavian artery, are supplied by the aortic arch. The innominate artery branches into the right subclavian artery and the right CCA in the most frequent form. Bilaterally, the vertebral arteries branch off the subclavian arteries.

The common carotid artery passes through the carotid sheath on either side before branching into the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA) . The ECA, which contains branches of the superior thyroid and ascending pharyngeal arteries, largely feeds blood to the face. There are no extracranial branches of the ICA.

The carotid sinus is a baroreceptor that is positioned at the carotid bifurcation and is innervated by the nerve of Hering, a branch of cranial nerve IX (the glossopharyngeal nerve). The carotid bifurcation also houses the carotid body, which acts as a chemoreceptor in response to low oxygen or high carbon dioxide levels.

The ICA contains an intracranial branch termed the ocular artery that connects to the external carotid blood supply. Carotid emboli commonly lodge in the ophthalmic artery, causing transitory monocular blindness (TMB) if they dissolve fast or central retinal artery blockage and blindness if they do not. Willis' intracranial circle facilitates communication between the ICA, ECA, and vertebrobasilar system.

 

Background

endarterectomy operation

The endarterectomy operation was devised and first performed at the University of Lisbon in 1946 by Portuguese surgeon Joao Cid dos Santos, who operated on an obstructed superficial femoral artery. An Argentine physician used a bypass surgery to heal a carotid artery blockage in 1951. Michael DeBakey successfully conducted the first endarterectomy circa 1953 at the Methodist Hospital in Houston, TX, albeit the method was not documented in the medical literature until 1975.

The first instance was published in The Lancet in 1954; the surgeon was Felix Eastcott, a consultant surgeon and deputy director of the surgical unit at St Mary's Hospital in London, UK. Eastcott's surgery was not technically an endarterectomy as we know it now; he removed the diseased portion of the artery and then sutured the healthy ends together.

Since then, proof for its efficacy in various patient categories has developed. Nearly 140,000 carotid endarterectomies were done in the United States in 2003, although the number of surgeries has continued to decline over time.

 

Indications for carotid endarterectomy

The North American Symptomatic Carotid Endarterectomy Trials (NASCET) were launched in 1987. Patients with moderate carotid stenosis (less than 70%) and severe carotid stenosis (more than 70%) were randomly allocated to treatment groups, with the majority of patients receiving antithrombotic medicine. individuals with severe carotid stenosis benefited significantly from surgery, but those with less than 50% stenosis benefited insignificantly with CEA.

Carotid endarterectomy is advised for individuals who have 50% or more stenosis of the carotid artery and a history of ipsilateral stroke or TIA. Amaurosis fugax, a painless transient loss of vision in one or both eyes that is sometimes characterized as a "curtain tumbling down" across the visual field, hemiparesis, facial paralysis, and speech loss are all symptoms of TIA.

Another significant research looked at asymptomatic patients with confirmed carotid disease. The Asymptomatic Carotid Artery Stenosis (ACAS) trials for endarterectomy shown that there is a substantial 5-year reduction in stroke risk in asymptomatic individuals with severe stenosis following the treatment.

Asymptomatic individuals with 70% or greater narrowing are also urged to have the procedure. As medical therapy has advanced since the 1980s, the CREST-2 study is now recruiting participants. The trial's goal is to compare intensive medical treatment to surgery in individuals with asymptomatic, high grade internal carotid stenosis.

Carotid duplex ultrasonography (CDU), which can measure the degree of carotid stenosis, can be used to examine asymptomatic people. According to Poiseuille's Law, the degree of the blockage corresponds with carotid flow velocity: the narrower the lumen of the channel, the greater the flow rate across the stenotic segment.

If there are tortuosities in the vessel, which might generate increased velocities, inaccuracies can be seen. Although CDU is beneficial for diagnosing hemodynamically significant stenosis, it has a limited specificity for individuals with 50% to 60% stenosis. Computed tomography angiography (CTA) and contrast-enhanced magnetic resonance angiography(CE-MRA) are two further types of screening .

These imaging modalities aid in the assessment of additional risk factors, such as plaque morphology, intracranial collateralization, and brain perfusion. When considering surgery, CTA or CE-MRA information can be utilized in conjunction with CDU to assist assess an individual patient's risk profile.

CEA must be conducted promptly after the beginning of symptoms in individuals with symptomatic carotid blockage (50-99 %). If CEA is conducted within two weeks of the beginning of symptoms, the number needed to treat for avoiding one stroke is five, which is recommended. If it has been more than two weeks from the beginning of symptoms or if the patient has had a stroke, the number needed to treat rises to 125.

CEA is beneficial in this group of patients if the symptoms are non-disabling and there is no tandem high-grade stenosis; however, CEA can be delayed if the stroke area is large (risk of cerebral edema), there is contralateral carotid occlusion, hemodynamic instability, and contralateral laryngeal palsy is a relative contraindication. In this situation, CEA is related with a higher rate of myocardial infarction.

Carotid artery stenting (CAS) is preferable in patients with symptomatic carotid blockage who have numerous comorbidities, a tracheostomy, or who have had previous neck radiation or dissection. Because to the advancement of the stents and method, there is a higher peri-procedural risk of stroke with CAS; however, results after CAS are equivalent to CEA in most cases.

 

Contraindications

Patients who are severely unwell and unable to undergo open surgery may be candidates for carotid angioplasty and stenting (CAS). Under local anesthetic, the stent, a tiny, flexible, mesh-like tube, is placed into the artery. The tube is then extended over a balloon to widen the artery lumen and enhance blood flow.

The Carotid Revascularization Endarterectomy vs Stenting Trials (CREST), a multi-institutional trial, found that CEA and CAS have comparable results in terms of postoperative complications such as restenosis, myocardial infarction, long-term stroke, and/or mortality. The risk of peri-procedural stroke was substantially greater in CAS patients, but the total risk of myocardial infarction was significantly higher in CEA patients.

While not an absolute contraindication, individuals who have had neck radiation therapy are at a greater risk of having transient cranial nerve damage during CEA, as well as late cerebrovascular events and restenosis after CAS. CEA is more technically difficult in the radiated neck because these patients have more diffuse plaques, adhesions, scar tissue, and wound problems as a result of radiation.

When compared to males, symptomatic women may be at higher risk of postoperative problems after CEA, but asymptomatic individuals had similar results and difficulties.

High risk criteria for carotid endarterectomy include the following:

  • Age ≥80 years
  • Class III/IV congestive heart failure
  • Class III/IV angina pectoris
  • Left main or multi vessel coronary artery disease
  • Need for open heart surgery within 30 days
  • Left ventricular ejection fraction of ≤30%
  • Recent (≤30 days) heart attack
  • Severe lung disease or chronic obstructive pulmonary disease
  • Severe renal disease
  • High cervical (C2) or intrathoracic lesion
  • Prior radical neck surgery or radiation therapy
  • Contralateral carotid artery occlusion
  • Prior ipsilateral carotic endarterectomy.
  • Contralateral laryngeal nerve injury
  • Tracheostoma

Carotid artery stenting is an alternative to carotid endarterectomy in cases where endarterectomy is considered too risky.

 

Carotid endarterectomy surgery

Carotid endarterectomy surgery

Prior to surgery, a patient having carotid endarterectomy should be on antiplatelet treatment (unless contraindicated). General anesthesia or local anaesthetic may be utilized for this surgery. The patient might be awake but drugged for local anesthesia. They will just experience numbness at the site of the procedure. The patient's neck, including the jaw and earlobe, should be wrapped and sterilized.

 

Incision

A cervical incision is done parallel to the sternocleidomastoid and prior to the carotid bifurcation. This incision can be prolonged proximally to the sternal notch for more proximal CCA lesions and distally to the mastoid process for more exposure. To avoid the parotid gland and the larger auricular nerve, its upper end should be directed posterior to the earlobe. The incision is made all the way through the platysma, and the sternocleidomastoid is withdrawn laterally with self-retaining retractors.

 

Exposure and mobilization

The internal jugular vein is shown, and the carotid sheath is opened along the vein's anterior border. The common facial vein is ligated, and the internal jugular vein is retracted laterally. To avoid damaging the vagus nerve, the dissection is continued anterior to the CCA. The vagus nerve is normally found in a posterior lateral location within the carotid sheath, however it can occasionally spiral anteriorly, especially around the incision's lower end.

The cranial nerves IX (glossopharyngeal nerve), X (vagus nerve), XI (accessory nerve), and XII (hypoglossal nerve), as well as the marginal mandibular branch of VII (facial nerve) and the rare nonrecurrent laryngeal nerve that comes directly off the vagus to innervate the vocal cords, should all be examined. This nerve can pass anterior to the carotid artery and be misidentified as a portion of the ansa cervicalis; if it is split mistakenly, cord paralysis follows. The right side of the neck is the most common location for a nonrecurrent laryngeal nerve.

The CCA is activated around the carotid lesion. The dissection is extended upward in order to separate the external carotid artery (ECA). The internal carotid artery (ICA) has been mobilized to the point where it is fully normal.

Because retraction can harm the hypoglossal nerve, every effort should be taken to limit traction on this nerve. To expose the distal ICA, the tethering artery and vein to the sternocleidomastoid, the descending hypoglossal branch of the ansa cervicalis, or the occipital artery may need to be divided.

The superior laryngeal nerve, which is normally placed medial to the ICA, should also be carefully examined. This nerve separates into external and internal branches that run posterior to the superior thyroid artery and may be injured if the surgeon attempts to regulate either this vessel or the ICA. The glossopharyngeal nerve crosses the ICA towards the base of the skull and is best preserved by keeping dissection close to the ICA's anterior surface.

Excessive or prolonged retraction of the top portion of the incision may result in transient compression injuries to the greater auricular nerve laterally or to the facial nerve's marginal mandibular branch medially. Several techniques can be used to mobilize the ICA distally in individuals with a high carotid bifurcation or an extensive lesion, as follows:

  • The skin incision can be prolonged up to the mastoid process, with the sternocleidomastoid fully mobilized toward its tendinous insertion on the mastoid process; care must be taken not to harm the accessory nerve, which enters the sternocleidomastoid substance at that level.
  • The digastric muscle can be mobilized anteriorly or split if required.
  • If further exposure is required, the styloid process can be transected and the mandible anteriorly subluxated.

 

Control of the CCA is achieved by encircling the vessel with umbilical tape close to the site of illness. If sinus bradycardia occurs, 1-2 mL of 1% lidocaine is injected into the carotid bifurcation tissues to treat reflex sympathetic bradycardia. After gaining proximal control, dissection is extended distally around the ECA and its first branch, the superior thyroid artery. Control is thus gained distally at the ICA.

It is critical to avoid manipulating the carotid artery during the dissection to prevent the danger of embolization. To prevent harming adjacent nerves, particularly the vagus and hypoglossal nerves, dissection must be performed with considerable caution. To assist the dissection, the ansa cervicalis, a branch of the hypoglossal nerve, may need to be separated; this is okay.

 

Arteriotomy and shunting

Heparin (5000-7000 U) is given intravenously (IV). In that sequence, the ICA, CCA, and ECA are occluded. An arteriotomy is performed with a No. 11 blade, beginning anteriorly on the CCA proximal to the lesion and extending cephalad through the plaque opposite the flow divider, then continuing into the ICA with Potts scissors. The arteriotomy is prolonged distal to the plaque until it reaches a point where the ICA is largely normal.

When general anesthesia is administered without cerebral monitoring, or when neurologic abnormalities are observed during monitoring, a shunt is implanted by putting the distal end of the shunt into the normal ICA distal to the lesion. Back-bleeding the shunt removes any air or debris, and the proximal end of the shunt is then implanted deep into the CCA, close to the plaque.

 

Removal of plaque

A Penfield elevator is used to start the actual endarterectomy. The plane between the inner and outer medial layers is the best for endarterectomy. By sharply separating the plaque in the CCA, the proximal terminus is reached. While the endarterectomy continues into the carotid bulb, the plaque can be lifted under full view. To reach an acceptable endpoint, carotid plaque that extends a short distance into the ICA may be teased medially toward the origin of the ECA. The plaque in the bulb can also be separated so that the ICA and ECA endarterectomies can be performed individually.

After the plaque is separated, the device used to regulate the ECA (clamp or loop) is relaxed, and an eversion endarterectomy is done. The split plaque in the ICA is feathered to provide a smooth taper in the transition to the normal distal intima. If a smooth distal taper cannot be obtained, interrupted 7-0 monofilament tacking sutures may be required to fix the endpoint.

All leftover debris and medial fibers are excised after the endarterectomy since they may contribute to embolization or hyperplastic restenosis. To assist visibility and removal of all debris, the endarterectomy surface is irrigated with heparinized saline solution. Before removing the clamps, each direction must be flushed. The ICA is the last to be unclamped. 

 

Closure

patch angioplasty

A patch angioplasty is typically used to close a traditional CEA. Although patch angioplasty closure is used in all patient categories, its advantages are especially noticeable in women, patients with tiny ICAs, current smokers, and patients who have previously had ipsilateral carotid surgery. Various patch materials, including the following, have been utilized with outstanding results:

  • Autogenous saphenous vein
  • Internal jugular vein
  • Polytetrafluoroethylene (PTFE)
  • Dacron
  • Bovine pericardium

 

Life expectancy after carotid endarterectomy

A Cochrane study published in 2020 indicated that CAS for symptomatic carotid stenosis was related with a higher risk of periprocedural stroke or mortality than CEA, with the majority of the increased risk owing to more frequent small, nondisabling strokes in persons over the age of 70. 

CAS was equally efficacious as CEA in avoiding recurrent stroke after the periprocedural period; however, the combination of procedural safety and long-term efficacy in preventing stroke recurrence preferred CEA. CAS may be related with a slight increase in the risk of periprocedural stroke or mortality in persons with asymptomatic carotid stenosis.

CEA patients exhibited a greater risk of perioperative stroke than CAS patients; this difference was most noticeable in symptomatic individuals. The use of CEA was linked to decreased procedure costs and readmission rates. The primary outcome consisted of a combination of in-hospital stroke and death. Despite a significantly increased medical risk in patients receiving TCAR, they discovered that in-hospital stroke/death rates were comparable for the two treatments.

 

Carotid endarterectomy complications

Complications during and after surgery are caused by a variety of variables, including the surgeon's expertise and technique, the patient's risk factors, and care before and after operation. CEA complications include:

Major complications

  • Myocardial Infarction
  • Hyperperfusion syndrome
  • Nerve Injury, particularly the cranial nerves: hypoglossal, vagus, glossopharyngeal, and facial (marginal mandibular) nerves
  • Perioperative stroke
  • Restenosis
  • Death

Minor Complications

  • Transient ischemic attack
  • Bleeding
  • Infection
  • Greater auricular nerve injury
  • Dysphagia

 

Conclusion 

Carotid endarterectomy is a stroke-prevention treatment that improves patient health and quality of life. Surgical therapy has been demonstrated to considerably reduce stroke and increase overall survival in individuals with moderate to severe carotid disease.

Patients who have had a TIA or have indications of carotid artery atherosclerosis are typically evaluated by their primary care provider or a nurse practitioner. If the workup confirms carotid artery stenosis, the patient should be referred to a neurologist and a vascular surgeon based on the degree of stenosis and the symptoms present.

In appropriately chosen patients, carotid endarterectomy has been found to minimize the risk of stroke. Stroke is another potential consequence of CEA; consequently, clinicians must inform the patient about the procedure's risks. The primary care physician should advise the patient to eliminate controllable stroke risk factors such as smoking, keeping a healthy weight, and decreasing cholesterol levels. Exercise on a regular basis is strongly suggested.