I. Overview
The carotid artery is a large vessel that carries blood from the heart to the head, face and neck, and is divided into the internal and external carotid arteries. The former enters the skull and carries blood to the brain and the eye, while the latter distributes to the scalp, maxillofacial area and thyroid gland. The internal carotid artery is one of the most important blood vessels supplying blood to the brain.
Carotid artery stenosis occurs in the bulb of the carotid artery and the beginning of the internal carotid artery, and can lead to occlusion of the internal carotid artery in severe cases. The brain is the most metabolically active organ in the human body and requires a large amount of blood supply; the weight of the brain accounts for 2% of the total body weight, but its blood requirement accounts for 15%-20% of the total body volume. Both carotid arteries supply more than 80% of the blood flow to brain tissues. Once carotid artery stenosis, occlusion or plaque dislodgement occurs, it will cause ischemic stroke due to corresponding brain tissue ischemia, resulting in serious neurological dysfunction, such as coma, limb paralysis, speech impairment, etc. In severe cases, it can directly lead to the patient’s death.
According to statistics, more than half of the cerebral infarcts are caused by carotid stenosis, and severe cerebral infarcts often lead to disability, loss of labor and social activities, and even direct death. Therefore, carotid stenosis has become one of the “number one killers” that endanger people’s health in today’s society.
Etiology
Atherosclerosis is the most common cause of carotid artery stenosis in middle-aged and elderly patients. Patients often have hypertension, diabetes mellitus, hyperlipidemia, and other risk factors that lead to cardiovascular and cerebrovascular damage, such as high salt and high fat diet and smoking. Atherosclerosis is caused by the accumulation of lipid substances on the walls of blood vessels gradually forming plaques, whose main components are the internal lipid core and the fibrous cap on the surface. The progressive enlargement of the plaque causes the lumen to narrow gradually, or the unstable plaque breaks down and the lipid components within the plaque are exposed in the lumen, leading to platelet aggregation and thrombus formation and thrombus dislodgement, both of which can lead to cerebral ischemic events.
Carotid artery stenosis due to atherosclerosis is often located in the bulb of the carotid artery and the beginning segment of the internal carotid artery. Other causes of carotid artery stenosis include carotid artery entrapment, aortitis, and secondary changes after radiation therapy to the neck.
The danger of carotid stenosis
Carotid artery stenosis is the main cause of ischemic stroke. The narrowing of carotid artery lumen diameter or even occlusion will directly cause insufficient perfusion of cerebral blood flow; in addition, when the plaque on the arterial blood vessel wall is dislodged and enters the cerebral blood vessels with blood flow, it will form emboli and block the cerebral blood vessels; the decrease of blood flow will cause the decrease of the clearance rate of emboli entering the cerebral blood vessels. In mild cases, single or multiple lacunar cerebral infarction may occur, and in severe cases, it leads to large area of brain tissue ischemia, which has a high rate of disability and death.
This may be related to poor lifestyle, excessive intake of high-fat and high-calorie foods, high work pressure, and excessive stress and strain. Once cerebrovascular diseases occur, the sequelae such as hemiplegia, aphasia and cognitive decline often appear, which not only cause great physical and mental pain to patients, but also bring huge mental and economic burdens to the society and families.
IV. Clinical manifestations
The patients are classified into “symptomatic carotid stenosis” and “asymptomatic carotid stenosis” according to whether they have had cerebral ischemic attacks or not. The clinical manifestations of symptomatic carotid stenosis are mainly related to cerebral ischemia caused by vascular stenosis. The main difference between the two is whether the ischemic symptoms can be completely resolved within 24 hours. Transient ischemic attack is classified as a transient ischemic attack if it can be completely resolved, while stroke is classified as a stroke if it cannot be completely resolved.
The ischemic symptoms caused by carotid stenosis mainly include: dizziness, memory loss, black haze attack, lateral deviation, limb numbness, weakness, unfavorable speech, and impaired consciousness.
V. Diagnosis and screening of high-risk groups
(I) Diagnosis
The diagnosis of carotid artery stenosis is mainly based on clinical symptoms, physical examination and imaging examinations. Imaging methods include morphological examination of the blood vessels in the neck and cranium and structural examination of brain tissue.
Vascular imaging.
Vascular imaging examinations mainly applied to the carotid artery include: carotid ultrasound, transcranial Doppler, CT angiography (CTA), digital subtraction angiography (DSA), etc.
Brain tissue imaging.
Mainly applied to the examination of brain tissue structures include: computed tomography (CT), magnetic resonance imaging (MRI) plain and diffusion-weighted imaging (DWI), for the assessment of ischemic changes in brain tissue.
(II) Screening of high-risk groups
1, middle-aged and elderly patients aged 50 years or older;
2.History of hypertension, diabetes mellitus, heavy smokers;
3, non-specific symptoms such as dizziness and memory loss;
4.Patients with a history of TIA attack, black haze attack and stroke. It is recommended to perform cervical vascular ultrasound and cervical vascular CTA examination.
VI. Treatment
The treatment of carotid stenosis mainly includes risk factor control, pharmacological treatment, surgical treatment and interventional treatment.
(I) Control of risk factors
Atherosclerotic carotid stenosis is often a part of systemic vascular lesions. Therefore, control of risk factors that can lead to vascular atherosclerosis is the basis of carotid stenosis treatment. It mainly includes: proper exercise, weight control, avoidance of obesity, smoking cessation, less alcohol consumption, reasonable control of blood pressure, blood sugar and blood lipids, etc.
(II) Drug treatment
Drug therapy mainly includes anti-platelet aggregation drugs and lipid-lowering drugs. The former are commonly used as aspirin and clopidogrel, while the latter are commonly used as statin lipid regulating drugs, which can play a role in stabilizing plaque. In addition, pharmacological treatment also includes medication for risk factors such as hypertension and diabetes mellitus. Drug therapy can only stabilize atherosclerotic plaques and minimize thrombosis, but it cannot fundamentally remove plaques or restore blood flow to brain tissue.
(C) Surgical treatment: carotid artery endarterectomy
Carotid endarterectomy (CEA) is the only method that can remove atherosclerotic plaque and reconstruct normal lumen and blood flow. After large-scale clinical trials and 60 years of clinical use in Europe and North America, it has been proven to be a safe and effective treatment for the prevention of ischemic strokes. Nowadays, CEA can reach 170,000 visits per year in North America and is the preferred treatment option and the “gold standard” for carotid stenosis.
However, there are still few medical institutions in China that can perform CEA, and statistics show that the total number of CEA cases performed in China is only about 1000 per year. The main reasons for this are the late implementation of CEA in China, the lack of training and awareness at the physician level, and the lack of awareness of the population about the dangers of the disease and the effectiveness of surgical treatment. Therefore, we should increase the popularization of the prevention of cerebrovascular diseases, inform patients clearly about the dangers of carotid stenosis, remove the “garbage” in the carotid vessels as soon as possible, and reduce the risk of cerebral infarction to avoid severe stroke and loss of the best treatment time.