| Carotid artery stenosis | |
|---|---|
| Other names | TIA - carotid artery [1] |
 | |
| Carotid artery disease | |
| Specialty | Vascular surgery |
Carotid artery stenosis is a narrowing or constriction of any part of the carotid arteries, usually caused by atherosclerosis. [2]
| Carotid artery stenosis | |
|---|---|
| Other names | TIA - carotid artery [1] |
| | |
| Carotid artery disease | |
| Specialty | Vascular surgery |
Carotid artery stenosis is a narrowing or constriction of any part of the carotid arteries, usually caused by atherosclerosis. [2]
The common carotid artery is the large artery whose pulse can be felt on both sides of the neck under the jaw. On the right side it starts from the brachiocephalic artery (a branch of the aorta), and on the left side the artery comes directly off the aortic arch. At the throat it forks into the internal carotid artery and the external carotid artery. The internal carotid artery supplies the brain, and the external carotid artery supplies the face. This fork is a common site for atherosclerosis, an inflammatory build-up of atheromatous plaque inside the common carotid artery, or the internal carotid arteries that causes them to narrow. [3] [4]
The plaque can be stable and asymptomatic, or it can be a source of embolization. Emboli break off from the plaque and travel through the circulation to blood vessels in the brain. As the vessels get smaller, an embolus can lodge in the vessel wall and restrict the blood flow to parts of the brain. This ischemia can either be temporary, yielding a transient ischemic attack (TIA), or permanent resulting in a thromboembolic stroke. [5]
Transient ischemic attacks are a warning sign and may be followed by severe permanent strokes, particularly within the first two days. TIAs by definition last less than 24 hours and frequently take the form of weakness or loss of sensation of a limb or the trunk on one side of the body or the loss of sight (amaurosis fugax) in one eye. Less common symptoms are artery sounds (bruits), or ringing in the ears (tinnitus). [6]
In asymptomatic individuals with a carotid stenosis, the risk of developing a stroke is increased above those without a stenosis. The risk of stroke is possibly related to the degree of stenosis on imaging. Some studies have found an increased risk with increasing degrees of stenosis [7] while other studies have not been able to find such a relationship. [8]
Atherosclerosis causes plaque to form within the carotid artery walls, usually at the fork where the common carotid artery divides into the internal and external carotid artery. The plaque build-up can narrow or constrict the artery lumen, a condition called stenosis. Rupture of the plaque can release atherosclerotic debris or blood clots into the artery. A piece of this material can break off and travel (embolize) up through the internal carotid artery into the brain, where it blocks circulation, and can cause death of the brain tissue, a condition referred to as ischemic stroke. [9]
Sometimes the stenosis causes temporary symptoms first, known as TIAs, where temporary ischemia occurs in the brain, or retina without causing an infarction. [10] Symptomatic stenosis has a high risk of stroke within the next 2 days. National Institute for Health and Clinical Excellence (NICE) guidelines recommend that people with moderate to severe (50–99% blockage) stenosis, and symptoms, should have "urgent" endarterectomy within 2 weeks. [11]
When the plaque does not cause symptoms, people are still at higher risk of stroke than the general population, but not as high as people 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 people with ≥60% stenosis who are expected to live at least 5 years after surgery. [12] [13] Surgeons are divided over whether asymptomatic people should be treated with medication alone or should have surgery. [14] [15]
The common carotid artery is the large vertical artery in red. The blood supply to the carotid artery starts at the arch of the aorta (bottom). The carotid artery divides into the internal carotid artery and the external carotid artery. The internal carotid artery supplies the brain. Plaque often builds up at that division and causes a narrowing (stenosis). Pieces of plaque can break off and block the small arteries above in the brain, which causes a stroke. Plaque can also build up at the origin of the carotid artery at the aorta.[ citation needed ]
Carotid artery stenosis is usually diagnosed by color flow duplex ultrasound scan of the carotid arteries in the neck. This involves no radiation, no needles and no contrast agents that may cause allergic reactions. This test has good sensitivity and specificity. [16]
Typically duplex ultrasound scan is the only investigation required for decision making in carotid stenosis as it is widely available and rapidly performed. However, further imaging can be required if the stenosis is not near the bifurcation of the carotid artery. [17]
One of several different imaging modalities, such as a computed tomography angiogram (CTA) [18] [19] [20] or magnetic resonance angiogram (MRA) may be useful. Each imaging modality has its advantages and disadvantages - Magnetic resonance angiography and CT angiography with contrast is contraindicated in patients with chronic kidney disease, catheter angiography has a 0.5% to 1.0% risk of stroke, MI, arterial injury or retroperitoneal bleeding. The investigation chosen will depend on the clinical question and the imaging expertise, experience and equipment available. [21]
For purpose of treatment, the degree of carotid stenosis is defined as:[ citation needed ]
The U.S. Preventive Services Task Force (USPSTF) recommends against routine screening for carotid artery stenosis in those without symptoms as of 2021. [22]
While routine population screening is not advised, the American Heart Association [23] and the Society for Vascular Surgery [24] recommend screening in those diagnosed with related medical conditions or have risk factors for carotid artery disease. [25] Screening is recommended for people who have:[ citation needed ]
The American Heart Association also recommends screening if a physician detects a carotid bruit, or murmur, over the carotid artery by listening through a stethoscope during a physical exam. For people with symptoms, the American Heart Association recommends initial screening using ultrasound.[ citation needed ]
The goal of treating carotid artery stenosis is to reduce the risk of stroke. The type of treatment depends on the severity of the disease and includes:[ citation needed ]
Clinical guidelines (such as those of the American Heart Association (AHA) [26] and National Institute for Clinical Excellence (NICE) [27] ) recommend that all patients with carotid stenosis be given medications to control their vascular risk factors, usually blood pressure lowering medications (if they have hypertension), diabetes medication (if they have diabetes), and recommend exercise, weight reduction (if overweight) and smoking cessation (for smokers). In addition, they would benefit from anti-platelet medications (such as aspirin or clopidogrel) and cholesterol lowering medication (such as statins, which were originally prescribed for their cholesterol-lowering effects but were also found to reduce inflammation and stabilize plaque).[ citation needed ]
According to the American Heart Association, interventions beyond medical management is based upon whether patients have symptoms:[ citation needed ]
All interventions for carotid revascularization (carotid endarterectomy, carotid stenting, and transcarotid artery revascularization) carry some risk of stroke; however, where the risk of stroke over time from medical management alone is high, intervention may be beneficial. Carotid artery stenting and carotid endarterectomy have been found to have similar benefits in patients with severe degree of carotid artery stenosis. [30] [31]
A transient ischemic attack (TIA), commonly known as a mini-stroke, is a minor stroke whose noticeable symptoms usually end in less than an hour. TIA causes the same symptoms associated with strokes, such as weakness or numbness on one side of the body, sudden dimming or loss of vision, difficulty speaking or understanding language, slurred speech, or confusion.
Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atherosclerosis. A deflated balloon attached to a catheter is passed over a guide-wire into the narrowed vessel and then inflated to a fixed size. The balloon forces expansion of the blood vessel and the surrounding muscular wall, allowing an improved blood flow. A stent may be inserted at the time of ballooning to ensure the vessel remains open, and the balloon is then deflated and withdrawn. Angioplasty has come to include all manner of vascular interventions that are typically performed percutaneously.
Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. These lesions may lead to narrowing of the arteries' walls due to buildup of atheromatous plaques. At onset there are usually no symptoms, but if they develop, symptoms generally begin around middle age. In severe cases, it can result in coronary artery disease, stroke, peripheral artery disease, or kidney disorders, depending on which body parts(s) the affected arteries are located in the body.
Cerebrovascular disease includes a variety of medical conditions that affect the blood vessels of the brain and the cerebral circulation. Arteries supplying oxygen and nutrients to the brain are often damaged or deformed in these disorders. The most common presentation of cerebrovascular disease is an ischemic stroke or mini-stroke and sometimes a hemorrhagic stroke. Hypertension is the most important contributing risk factor for stroke and cerebrovascular diseases as it can change the structure of blood vessels and result in atherosclerosis. Atherosclerosis narrows blood vessels in the brain, resulting in decreased cerebral perfusion. Other risk factors that contribute to stroke include smoking and diabetes. Narrowed cerebral arteries can lead to ischemic stroke, but continually elevated blood pressure can also cause tearing of vessels, leading to a hemorrhagic stroke.
Vascular surgery is a surgical subspecialty in which vascular diseases involving the arteries, veins, or lymphatic vessels, are managed by medical therapy, minimally-invasive catheter procedures and surgical reconstruction. The specialty evolved from general and cardiovascular surgery where it refined the management of just the vessels, no longer treating the heart or other organs. Modern vascular surgery includes open surgery techniques, endovascular techniques and medical management of vascular diseases - unlike the parent specialities. The vascular surgeon is trained in the diagnosis and management of diseases affecting all parts of the vascular system excluding the coronaries and intracranial vasculature. Vascular surgeons also are called to assist other physicians to carry out surgery near vessels, or to salvage vascular injuries that include hemorrhage control, dissection, occlusion or simply for safe exposure of vascular structures.
Stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly.
Amaurosis fugax is a painless temporary loss of vision in one or both eyes.
An atheroma, or atheromatous plaque, is an abnormal accumulation of material in the inner layer of an arterial wall.
Carotid endarterectomy is a surgical procedure used to reduce the risk of stroke from carotid artery stenosis. In endarterectomy, the surgeon opens the artery and removes the plaque. The plaque forms and thickens the inner layer of the artery, or intima, hence the name of the procedure which simply means removal of part of the internal layers of the artery.
Cerebral infarction is the pathologic process that results in an area of necrotic tissue in the brain. It is caused by disrupted blood supply (ischemia) and restricted oxygen supply (hypoxia), most commonly due to thromboembolism, and manifests clinically as ischemic stroke. In response to ischemia, the brain degenerates by the process of liquefactive necrosis.
A watershed stroke is defined as a brain ischemia that is localized to the vulnerable border zones between the tissues supplied by the anterior, posterior and middle cerebral arteries. The actual blood stream blockage/restriction site can be located far away from the infarcts. Watershed locations are those border-zone regions in the brain supplied by the major cerebral arteries where blood supply is decreased. Watershed strokes are a concern because they comprise approximately 10% of all ischemic stroke cases. The watershed zones themselves are particularly susceptible to infarction from global ischemia as the distal nature of the vasculature predisposes these areas to be most sensitive to profound hypoperfusion.
Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory disease of the blood vessels that causes abnormal growth within the wall of an artery. FMD has been found in nearly every arterial bed in the body, although the most commonly affected are the renal and carotid arteries.
A Hollenhorst plaque is a cholesterol embolus that is seen in a blood vessel of the retina. It is usually found when a physician performs ophthalmoscopy, during which a plaque will appear as a small, bright crystal that is refractile and yellow. This is a medical exam finding, and is not a medical condition, though it may be related to cardiovascular conditions such as atherosclerosis of the internal carotid artery. It was first described by American ophthalmologist Robert Hollenhorst in 1961.
Carotid artery dissection is a separation of the layers of the artery wall in the carotid arteries supplying oxygen-bearing blood to the head. It is the most common cause of stroke in younger adults.The term 'cervical artery dissection should also be considered in the context of this article.
Carotid artery stenting is an endovascular procedure where a stent is deployed within the lumen of the carotid artery to treat narrowing of the carotid artery and decrease the risk of stroke. It is used to treat narrowing of the carotid artery in high-risk patients, when carotid endarterectomy is considered too risky.
Intima–media thickness (IMT), also called intimal medial thickness, is a measurement of the thickness of tunica intima and tunica media, the innermost two layers of the wall of an artery. The measurement is usually made by external ultrasound and occasionally by internal, invasive ultrasound catheters. Measurements of the total wall thickness of blood vessels can also be done using other imaging modalities.
Andrew Nicolaides is a British-Greek Cypriot surgeon, and an expert in cardiovascular disease and stroke prevention.
John David Spence is a Canadian medical doctor, medical researcher and Professor Emeritus at the University of Western Ontario. He is affiliated with the University of Western Ontario and the Robarts Research Institute, one of Canada's leading medical research organizations. Before his retirement from clinical practice in July 2022, he was also affiliated with the London Health Sciences Centre's University Hospital. He is a recognized expert in stroke prevention and stroke prevention research, with more than 600 peer-reviewed publications since 1970. He delivered more than 600 lectures on stroke prevention in 42 countries. In 2015, he received the Research Excellence Award from the Canadian Society for Atherosclerosis, Thrombosis and Vascular Biology. In 2019, he was appointed a Member of the Order of Canada, and in 2020 he received the William Feinberg Award from the American Heart Association for excellence in clinical stroke research.
Embolic stroke of undetermined source (ESUS) is an embolic stroke, a type of ischemic stroke, with an unknown origin, defined as a non-lacunar brain infarct without proximal arterial stenosis or cardioembolic sources. As such, it forms a subset of cryptogenic stroke, which is part of the TOAST-classification. The following diagnostic criteria define an ESUS:
Brajesh Lal, born in 1963 in Varanasi, India and of Indian origin, is an American surgeon, and an expert in vascular disease, particularly the prevention and treatment of stroke and venous disease.
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