Carotid artery stenosis

Introduction to carotid stenosis Carotid stenosis is a symptom of stenosis as a carotid artery that leads from the heart to the main blood vessels in the brain and other parts of the head. Carotid stenosis is mostly due to atherosclerotic plaque caused by carotid atherosclerotic plaque, the incidence of carotid stenosis is high, about 9% of carotid stenosis in people over 60 years old, mostly in the common carotid artery Bifurcation and initial segment of the internal carotid artery. Some stenotic lesions may even progress to fully occlusive lesions. Carotid stenosis can be treated by medication or surgery. basic knowledge Proportion of disease: About 0.05% of patients with carotid stenosis in people over 60 years old Susceptible people: no special people Mode of infection: non-infectious Complications: transient ischemic attack

Causes of carotid stenosis

Disease factor (45%)

1. Atherosclerosis: Atherosclerosis is a disease in which a layer of lipid like millet porridge is deposited on the arterial wall to reduce arterial elasticity and narrow the lumen. It occurs mostly in the large and middle arteries, including the coronary artery of the heart, the cerebral artery of the head, and the like.

2, arteritis: refers to the chronic non-specific inflammatory disease of the aorta and its main branches and pulmonary artery. Among them, the brachiocephalic blood vessels, renal artery, thoracic and abdominal aorta and superior mesenteric artery are the most common sites, often multiple, and the clinical manifestations vary with different lesions. It can cause arterial stenosis and occlusion in different parts, and a few can cause aneurysms.

Trauma (25%)

External damage caused by a blow, collision or chemical attack on the body or object.

Radioactive injury (15%)

Caused by high-energy ionizing radiation, radium and various radioisotope-induced tissue damage.

Pathogenesis

The best site for the common carotid artery bifurcation, followed by the beginning of the common carotid artery, in addition to the internal carotid artery siphon, middle cerebral artery and anterior cerebral artery.

It is generally believed that carotid plaque causes cerebral ischemia mainly through two ways: one is a hemodynamic change caused by a severely narrow carotid artery, resulting in hypoperfusion of the corresponding part of the brain; the other is plaque The embolus or micro-thrombosis on the surface of the plaque causes cerebral embolism. The above two mechanisms are more dominant. The current view is still inconsistent, but most of them believe that plaque stenosis and plaque morphology are closely related to cerebral ischemia. Related, the two together act to induce neurological symptoms, and the relationship between stenosis and symptoms can be more closely related.

Prevention of carotid stenosis

1. Because the main cause of this disease is atherosclerosis, aortitis, trauma and radiation damage, active treatment and prevention of primary disease is the key to prevent this disease.

2. It is found that there are obvious carotid stenosis can be performed by carotid percutaneous transluminal angioplasty or carotid stenting to eliminate potential emboli sources and prevent stroke.

Carotid stenosis complications Complications transient ischemic attack

Large-scale clinical data show that 50% of carotid stenosis increases the risk of transient ischemic attack and stroke by 4%.

Symptoms of carotid stenosis Common symptoms Coma cerebral ischemia, insomnia, drowsiness, vascular murmur, hemian atherosclerosis, tinnitus, sensory disturbance, vertigo

Carotid stenosis caused by atherosclerosis is more common in middle-aged and elderly people, often accompanied by a variety of cardiovascular risk factors. Carotid stenosis caused by brachiocephalic arteritis is more common in adolescents, especially young women. Carotid stenosis caused by injury or radiation, with a history of injury or radiation exposure before onset. Clinically, according to whether carotid stenosis produces cerebral ischemia symptoms, it is divided into two categories: symptomatic and asymptomatic.

Symptomatic carotid stenosis

(1) Cerebral ischemia symptoms may include tinnitus, dizziness, darkness, blurred vision, dizziness, headache, insomnia, memory loss, lethargy, and more dreams. Ocular ischemia is characterized by decreased vision, hemianopia, and diplopia.

(2) The transient loss of local neurological function in TIA is a transient disorder of one limb sensation or motor function, transient monocular blindness or aphasia, etc., usually only lasts for several minutes, and completely recovers within 24 hours after onset. Imaging examination showed no focal lesions.

(3) Common clinical symptoms of ischemic stroke include one-sided limb sensory disturbance, hemiplegia, aphasia, cranial nerve injury, severe coma, etc., and have corresponding neurological signs and imaging features.

2. Asymptomatic carotid stenosis

Many patients with carotid stenosis are clinically free of any signs and symptoms of the nervous system. Sometimes, only during the physical examination, the carotid pulsation is weakened or disappeared, and the neck or carotid artery passes through the vascular murmur. Asymptomatic carotid stenosis, especially severe stenosis or plaque ulcer, is recognized as a "high-risk disease" and is receiving increasing attention.

Carotid stenosis examination

Doppler-ultrasound examination

Doppler-ultrasound is a combination of Doppler flowmetry and real-time imaging of B-ultrasound. It is the first choice for non-invasive carotid examination. It is simple, safe and inexpensive. It can not only display Anatomical images of the carotid artery, plaque morphology examination, such as distinguishing plaque hemorrhage and plaque ulcer, but also showing arterial blood flow, flow rate, blood flow direction and intra-arterial thrombosis, the accuracy of diagnosis of carotid stenosis More than 95%, Doppler-ultrasound has been widely used in the screening and follow-up of carotid stenosis.

The inadequacies of ultrasound examination include:

1 can not check the lesions of the intracranial internal carotid artery;

2 Inspection results are susceptible to the skill level of the operator.

2. Magnetic resonance angiography

Magnetic resonance angiography (MRA) is a non-invasive angiography technique that clearly shows the three-dimensional shape and structure of the carotid artery and its branches, and can reconstruct the intracranial arteries. The contour is particularly suitable for MRA examination. MRA can accurately display thrombotic plaque, presence of dissection aneurysm and intracranial artery, which is very helpful for diagnosis and determination.

The disadvantage of MRA is that slow blood flow or complicated blood flow often causes signal loss, exaggeration of narrowness, and also has limitations in displaying hardened plaque. There are metal retention in the body (such as metal stent, pacemaker or metal). Patients with prostheses, etc.) are MRA contraindications.

3. CT angiography

CT angiography (CTA) is a non-invasive angiography technique developed on the basis of spiral CT. The method is to inject a contrast agent through a blood vessel, and the contrast agent concentration in the circulating blood or target blood vessels reaches the peak period. Volumetric scanning is performed, and then processed to obtain a digital stereoscopic image. The external carotid artery is suitable for CTA examination. The main reason is that the neck artery is perpendicular to the CT section, thus avoiding the relative resolution of the horizontally oriented vessels during spiral CT scanning. Insufficient shortcomings, the advantages of CTA can directly display calcified plaques. At present, three-dimensional revascular reconstruction generally uses surface shaded display (SSD), maximum intensity projection (MIP), and MIP reconstructed images to obtain similar blood vessels. Contrast images, and can show calcification and wall thrombus, but the three-dimensional relationship is not as good as SDD, but SDD can not directly show the difference in density.

CTA technology has been widely used in the diagnosis of carotid stenosis, but the technology is not mature enough, and further experience is needed to improve it.

4. Digital subtraction angiography

Although non-traumatic imaging methods have been increasingly used for the diagnosis of cervical artery lesions, each method has certain advantages and disadvantages, high-resolution MRA, CTA, Doppler-ultrasound imaging for the initial diagnosis, Follow-up is of great value. Although angiography is no longer a method of census, initial diagnosis and follow-up, digital subtraction angiography (DSA) is still the diagnosis of carotid stenosis in accurately evaluating lesions and determining treatment options. The "gold standard", DSA examination of carotid stenosis should include aortic arch angiography, bilateral common carotid artery selective angiography, selective intracranial carotid artery angiography, bilateral vertebral artery selective angiography and basilar artery selective angiography, DSA can understand the location, extent and extent of the lesion and the formation of the collateral; help determine the nature of the lesion such as ulcers, calcification and thrombosis; understand the coexisting vascular lesions such as aneurysms, vascular malformations, etc., angiography can be surgery And interventional therapy provides the most valuable imaging basis.

Arterial angiography is a means of traumatic examination, and it is expensive. The literature reports that the incidence of complications is 0.3% to 7%. The main complications are cerebral vasospasm, detachment of plaques, stroke, cerebral embolism and contrast agent allergy. Renal dysfunction, vascular injury and hematoma at the puncture site, pseudoaneurysm, etc.

5. Method for measuring carotid stenosis

Although ultrasound, computerized tomography (CT), magnetic resonance imaging (MRI) and other non-invasive tests are increasingly used in the diagnosis of carotid stenosis, angiography is still the diagnosis of carotid stenosis. The "gold standard", the degree of carotid stenosis is determined according to the results of angiography, different research departments have adopted different measurement methods, there are two commonly used measurement methods in the world, namely the North American Symptomatic Carotid Endarterectomy Trial Collaborative Group (North American Symptomatic Carotid Endarterectomy Trial Collaborators, NASCET) Standard and European Carotid Surgery Trial collaborators Group (ECST) standards.

NASCET stenosis = (1 - the narrowest blood flow width of the internal carotid artery / the diameter of the normal internal carotid artery at the distal end of the stenosis lesion) × 100%

ECST stenosis = (1 - the narrowest blood flow width of the internal carotid artery / simulated internal diameter of the internal carotid artery) × 100%

Both methods have classified the degree of internal carotid artery stenosis into four levels:

1 mild stenosis, the inner diameter of the artery is reduced by <30%;

2 moderate stenosis, the inner diameter of the artery is reduced by 30% to 69%;

3 severe stenosis, the inner diameter of the artery was reduced by 70% to 99%; 4 was completely occluded.

Diagnosis and differentiation of carotid stenosis

Diagnostic criteria

1. Men over 60 years of age have a long-term smoking history, obesity, hypertension, diabetes and hyperlipidemia and other risk factors for cardiovascular and cerebrovascular diseases.

2. Carotid vascular murmurs were found during physical examination.

3. A comprehensive analysis of the results of non-invasive auxiliary examination can make a diagnosis.

Differential diagnosis

1. Risk factors for carotid stenosis and high-risk groups

Atherosclerosis is a systemic disease, age (>60 years), gender (male), long-term smoking, obesity, hypertension, diabetes and hyperlipidemia, and other risk factors for cardiovascular and cerebrovascular diseases, also applicable to atherosclerosis Screening for carotid stenosis caused by sclerosis.

High-risk groups include patients with TIA and ischemic stroke, patients with lower extremity arteriosclerosis obliterans, coronary heart disease (especially those requiring coronary artery bypass or interventional therapy), and carotid vascular murmurs found during physical examination.

2. Diagnosis basis

Carotid stenosis can be diagnosed by clinical manifestations and non-invasive assisted examinations, but DSA is still an indispensable basis for diagnosis and formulation.

3. Clinical evaluation of patients with carotid stenosis

Clinical evaluation of patients with carotid stenosis caused by atherosclerosis includes the following: 1 evaluation of risk factors; 2 cardiac examination; 3 peripheral vascular examination; 4 brain function evaluation, including systemic neurological examination and brain CT or MRI Imaging studies, neurological examinations include: state of consciousness, brain nerves, exercise, sensory and coordination tests.

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