Carotid endarterectomy (CEA) is a
surgicalSurgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
procedure used to prevent stroke, by correcting stenosis (narrowing) in the
common carotid arteryIn human anatomy, the common carotid artery is an artery that supplies the head and neck with oxygenated blood; it divides in the neck to form the external and internal carotid arteries. - Structure :...
.
EndarterectomyEndarterectomy is a surgical procedure to remove the atheromatous plaque material, or blockage, in the lining of an artery constricted by the buildup of soft/hardening deposits. It is carried out by separating the plaque from the arterial wall....
is the removal of material on the inside (
end-) of an
arteryArteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
.
AtherosclerosisAtherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
causes
plaquePlaque or placque may refer to:* Commemorative plaque, a flat ornamental plate or tablet fixed to a wall, used to mark a significant event, person, etc.* Memorial Plaque, issued to next-of-kin of dead British military personnel after World War I...
to form in the carotid arteries, usually at the fork where the common carotid artery divides into the internal and external carotid artery. The plaque can build up in the inner surface of the artery (
lumenA lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
), and narrow or constrict the artery. Pieces of the plaque, called emboli, can break off (i.e. embolize) and travel up the internal carotid artery to the brain, where it blocks circulation, and can cause death of the brain tissue.
Sometimes the plaque causes symptoms first. The symptoms are temporary or transitory strokes, known as
transient ischemic attackA transient ischemic attack is a transient episode of neurologic dysfunction caused by ischemia – either focal brain, spinal cord or retinal – without acute infarction...
s (TIAs). By definition, TIAs last less than 24 hours; after 24 hours they are called strokes. Symptomatic stenosis has a high risk of stroke within the next 2 days.
National Institute for Health and Clinical ExcellenceThe National Institute for Health and Clinical Excellence is a special health authority of the English National Health Service , serving both English NHS and the Welsh NHS...
(NICE) guidelines recommend that patients with moderate to severe (50-99% blockage) stenosis, and symptoms, should have "urgent" endarterectomy within 2 weeks.
When the plaque doesn't cause symptoms, patients are still at higher risk of stroke than the general population, but not as high as patients with symptomatic stenosis. The incidence of stroke, including fatal stroke, is 1–2% per year. The surgical mortality of endarterectomy ranges from 1–2% to as much as 10%. Two large randomized clinical trials have demonstrated that carotid surgery done with a 30-day stroke and death risk of 3% or less will benefit asymptomatic patients with ≥60% stenosis who are expected to live at least 5 years after surgery. Surgeons are divided over whether asymptomatic patients should be treated with medication alone or should have surgery.
In endarterectomy, the surgeon opens the artery and removes the plaque. The plaque forms and enlarges in the inner layer of the artery, or
endotheliumThe endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells. Endothelial cells line the entire circulatory system, from the heart...
, hence the name of the procedure which simply means removal of the endothelium of the artery.A newer procedure, endovascular
angioplastyAngioplasty is the technique of mechanically widening a narrowed or obstructed blood vessel, the latter typically being a result of atherosclerosis. An empty and collapsed balloon on a guide wire, known as a balloon catheter, is passed into the narrowed locations and then inflated to a fixed size...
and
stentIn the technical vocabulary of medicine, a stent is an artificial 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow...
ing, threads a catheter up from the groin, around the aortic arch, and up the carotid artery. The catheter uses a balloon to expand the artery, and inserts a stent to hold the artery open. In several clinical trials,the 30-day incidence of heart attack, stroke, or death was significantly higher with stenting than with endarterectomy (9.6% vs. 3.9%)
The Carotid Revascularization Endarterectomy versus Stenting Trial (CREST) funded by the
National Institutes of HealthThe National Institutes of Health are an agency of the United States Department of Health and Human Services and are the primary agency of the United States government responsible for biomedical and health-related research. Its science and engineering counterpart is the National Science Foundation...
(NIH) reported that the results of stents and endarterectomy were comparable. However, the European International Carotid Stenting Study (ICSS) found that stents had almost double the rate of complications.
Procedure
The internal, common and external carotid arteries are clamped, the lumen of the internal carotid artery is opened, and the atheromatous plaque substance removed. The artery is closed,
hemostasisHemostasis or haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel . Most of the time this includes blood changing from a liquid to a solid state. Intact blood vessels are central to moderating blood's tendency to clot...
achieved, and the overlying layers closed. Many surgeons lay a temporary
shuntIn medicine, a shunt is a hole or a small passage which moves, or allows movement of fluid from one part of the body to another. The term may describe either congenital or acquired shunts; and acquired shunts may be either biological or mechanical.* Cardiac shunts may be described as...
to ensure blood supply to the
brainThe brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
during the procedure. The procedure may be performed under general or local anaesthesia. The latter allows for direct monitoring of neurological status by intra-operative verbal contact and testing of grip strength. With general anaesthesia indirect methods of assessing cerebral perfusion must be used, such as
electroencephalographyElectroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
(EEG), transcranial doppler analysis and carotid artery stump pressure monitoring. At present there is no good evidence to show any major difference in outcome between local and general anaesthesia.
Minimally invasive procedures have been developed, by threading catheters through the
femoral arteryThe femoral artery is a general term comprising a few large arteries in the thigh. They begin at the inguinal ligament and end just above the knee at adductor canal or Hunter's canal traversing the extent of the femur bone....
, up through the
aortaThe aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
, then inflating a balloon to dilate the carotid artery, with a wire-mesh stent and a device to protect the brain from embolization of plaque material. The FDA has approved 5 carotid stent systems as safe and effective in patients at increased risk of complications for neck surgery. In the SAPPHIRE study, Yadav concluded that this procedure, known as
carotid stentingCarotid artery stenting is an endovascular, catheter-based procedure which unblocks narrowings of the carotid artery lumen to prevent a stroke. Carotid artery stenosis can present with no symptoms or with symptoms such as transient ischemic attacks or cerebrovascular accidents...
, was non-inferior to carotid endarterectomy in total adverse events, and lowered event rates for major stroke, cranial nerve palsy, and
myocardial infarctionMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
, in patients at high risk for surgery. It is the consensus of experts in the field that carotid artery stenting should be considered an option for patients who require carotid artery revascularization to prevent stroke and who are at increased risk of having surgical complications.
History
The endarterectomy procedure was developed and first done by the Portuguese surgeon Joao Cid dos Santos in 1946, when he operated an occluded superficial femoral artery, at the
University of Lisbon. Later, surgical intervention to relieve atherosclerotic obstruction of the carotid arteries was successfully performed by Dr. Michael DeBakey in 1953 for the first time, at the
Methodist HospitalMethodist Hospital is the name of numerous medical institutions.* The Methodist Hospital, Houston, Texas* Methodist Medical Center of Illinois, Peoria, Illinois* Methodist Hospital of Indianapolis, Indianapolis, Indiana...
in Houston, TX. The first case to be recorded in the medical literature was in The Lancet in 1954. and the surgeon was Felix Eastcott, a consultant surgeon and deputy director of the surgical unit at St Mary's Hospital, London UK. A reprint of his article together with a modern commentary can be found on-line
http://www.grandrounds-e-med.com/articles/gr049005.htm. Eastcott's procedure was not strictly an endarterectomy as we now understand it; he excised the diseased part of the artery and then resutured the healthy ends together. Since then, evidence for its effectiveness in different patient groups has accumulated. In 2003 nearly 140,000 carotid endarterectomies were performed in the USA (Halm).
Indications
The aim of CEA is to prevent the adverse sequelae of carotid artery stenosis secondary to atherosclerotic disease, i.e. stroke. As with any prophylactic operation, careful evaluation of the relative benefits and risks of the procedure is required on an individual patient basis. Peri-operative combined mortality and major stroke risk is 2–5%.
Carotid stenosis is diagnosed with
ultrasound dopplerDiagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...
studies of the neck arteries,
magnetic resonance angiographyMagnetic resonance angiography is a group of techniques based on Magnetic Resonance Imaging to image blood vessels. Magnetic resonance angiography is used to generate images of the arteries in order to evaluate them for stenosis , occlusion or aneurysms...
(MRA) or
computed tomography angiographyComputed tomography angiography is a computed tomography technique used to visualize arterial and venous vessels throughout the body. This ranges from arteries serving the brain to those bringing blood to the lungs, kidneys, arms and legs.-Technique:...
(CTA). The
circle of WillisThe Circle of Willis is a circle of arteries that supply blood to the brain...
typically provides a collateral blood supply. Surgical management of symptomatic stenoses has a much higher
therapeutic indexThe therapeutic index is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes death or toxicity ....
with regard to asymptomatic lesions.
The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the European Carotid Surgery Trial (ECST) are both large randomized class 1 studies which have helped define current indications for carotid endarterectomy. The NASCET found that for every six patients treated, one major stroke would be prevented at two years (i.e. a
number needed to treatThe number needed to treat is an epidemiological measure used in assessing the effectiveness of a health-care intervention, typically a treatment with medication. The NNT is the average number of patients who need to be treated to prevent one additional bad outcome...
(NNT) of six) for symptomatic patients with a 70–99% stenosis, where percent stenosis was defined as:
- percent stenosis = ( 1 − ( minimal diameter ) / ( poststenotic diameter ) ) × 100%.
Symptomatic patients with less severe carotid occlusion (50–69%) had a smaller benefit, with a NNT of 22 at five years (Barclay). In addition, co-morbidity adversely affects the outcome; patients with multiple medical problems have a higher post-operative
mortality rateMortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...
and hence benefit less from the procedure. For asymptomatic patients (those without TIA or strokes) the European asymptomatic carotid surgery trial (ACST) found that asymptomatic patients may also benefit from the procedure, but only the group with a high grade stenosis (60% or more). For maximum benefit patients should be operated on soon after a TIA or stroke, preferably within the first month.
Contraindications
The procedure cannot be performed in case of:
- Complete internal carotid artery obstruction (because there is no benefit to treating chronic occlusion).
- Previous stroke on the ipsilateral side with heavy sequelae, because there is no benefit in preventing what has already happened, or risking making it worse.
- Patient deemed unfit for the operation by the surgeon or anaesthesiologist.
Complications
About 3% of asymptomatic and 6% of symptomatic patients are expected to suffer stroke or death as a result of either the surgery or carotid stenting. Other surgical complications include Hemorrhage of the wound bed, which is potentially life-threatening, as swelling of the neck due to
hematomaA hematoma, or haematoma, is a localized collection of blood outside the blood vessels, usually in liquid form within the tissue. This distinguishes it from an ecchymosis, which is the spread of blood under the skin in a thin layer, commonly called a bruise...
could compress the
tracheaIn tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
. Rarely, the
hypoglossal nerveThe hypoglossal nerve is the twelfth cranial nerve , leading to the tongue. The nerve arises from the hypoglossal nucleus and emerges from the medulla oblongata in the preolivary sulcus separating the olive and the pyramid. It then passes through the hypoglossal canal...
can be damaged during surgery. This is likely to result in fasciculations developing on the
tongueThe tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...
and paralysis of the affected side: on sticking it out, the patients tongue will deviate toward the affected side.
Another rare but potentially serious complication is hyperperfusion syndrome because of the sudden increase in perfusion of the vasculature distal to stenosis.