The carotid artery is the main blood vessel leading from the heart to the brain and other parts of the head. Carotid artery stenosis is mostly due to narrowing of the carotid lumen caused by atheromatous plaque in the carotid artery. Some stenotic lesions may even progress to complete occlusive lesions.
Etiology
The main causes of carotid stenosis are atherosclerosis, aortitis and fibromuscular dysplasia, while other causes such as trauma, arterial torsion, congenital arterial atresia, tumors, arterial or periarteritis, and fibrosis after radiation therapy are less common. In the West, about 90% of carotid stenotic lesions are due to atherosclerosis. In China, aortitis is also a common cause of carotid artery stenosis.
Diagnosis
1.Males older than 60 years old with a history of long-term smoking, obesity, hypertension, diabetes mellitus and hyperlipidemia, and other risk factors for cardiovascular diseases.
2.Carotid artery vascular murmur was found during physical examination.
3.The diagnosis can be made by comprehensive analysis of the results of non-invasive auxiliary tests.
Prevention
According to foreign studies, the risk of stroke within 1 year for asymptomatic severe carotid stenosis (>70%) is 2% to 5%, and the annual stroke rate for those with ulcerated plaque is 7.5%. The recurrence rate of stroke within 1 year is 59% for carotid stenosis with stroke attack, and about 35% of ischemic cerebrovascular diseases in Europe and the United States are caused by carotid stenosis.
1, because the main cause of this disease is atherosclerosis, aortitis, trauma and radiation injury, so active treatment and prevention of the original disease is the key to prevent this disease.
2. Carotid percutaneous transluminal angioplasty or carotid stenting implantation can be done to eliminate potential sources of emboli and prevent the occurrence of stroke if significant carotid stenosis is found.
Treatment
Treatment of carotid stenosis is aimed at improving cerebral blood supply, correcting or relieving symptoms of cerebral ischemia; preventing TIA and ischemic stroke. Treatment is based on the degree of carotid artery stenosis and the patient’s symptoms, including medical treatment, surgical treatment and interventional treatment.
1. Internal treatment
The purpose of conservative medical treatment is to reduce the symptoms of cerebral ischemia, reduce the risk of stroke, and control the existing diseases such as hypertension, diabetes, hyperlipidemia and coronary heart disease. Conservative medical treatment includes the following.
(1) Reducing body weight.
(2) Quit smoking.
(3) Limiting alcohol consumption.
(4) Anti-platelet aggregation therapy: Many randomized, prospective multicenter large clinical trials have confirmed that anti-platelet aggregation drugs can significantly reduce the incidence of cerebral ischemic disease, the drugs commonly used in clinical practice are aspirin, ticlopidine (ticlopidine, the trade name against kleider), etc.
(5) Improve the symptoms of cerebral ischemia.
(6) Regular ultrasound examination, dynamic monitoring of changes in the condition.
2.Surgical treatment
The aim of surgical treatment of carotid stenosis is to prevent the occurrence of stroke, and secondly, to prevent and slow down the onset of TIA. The standard surgical procedure is carotid endarterectomy (CE). Carotid endarterectomy was introduced in 1954, with some initial attempts showing poor results, but as the technique continued to improve, complications became less frequent, and by the mid-1980s approximately 100,000 people in the United States were undergoing CE each year.
In the early 1990s, several large-scale, multicenter clinical trials were reported that objectively evaluated the effectiveness and safety of CE, and three of the most influential trials were the ECST, NASCET, and the Asymptomatic Carotid Atherosclerosis Study (ACAS). Both ECST and NASCET were conducted in patients with symptomatic severe carotid stenosis, and the findings of both trials were consistent.
(i) CE treatment was more effective than medical drug therapy for symptomatic carotid stenosis, and patients with carotid stenosis of 70% to 99% benefited significantly from CE;
(ii) Patients with 0% to 29% stenosis are less likely to have a stroke within 3 years, and the risk of CE far outweighs the benefit, so CE is not recommended;
The results of the ACAS study of asymptomatic carotid atherosclerosis patients randomized to CE and drug therapy showed that the cumulative stroke and mortality rates for patients with carotid stenosis ≥ 60% were 5.1% and 11.0%, respectively, and that the effect of CE was much better than that of drug therapy. The complications of CE include perioperative stroke and death; also cerebral nerve injury, wound hematoma infection, postoperative hypertension, and postoperative hyperperfusion syndrome; the incidence of myocardial infarction and hypotension is low.
3.Interventional treatment
(1) Carotid artery percutaneous endoluminal angioplasty Percutaneoustransluminal angioplasty (PTA) is a relatively mature vascular recanalization technique, which is mainly performed by filling the balloon to squeeze the stenotic segment of the vessel from the inside out, causing fracture damage to the vessel wall and achieving the purpose of dilation. This technique has been widely used in various vascular diseases throughout the body, such as renal artery, iliac artery, coronary artery, etc. Compared with other vascular diseases, the application of PTA in carotid artery stenosis has been slower because of technical reasons such as the complexity of the PTA operation route and the concern of complications such as vessel rupture and cerebral infarction caused by embolus dislodgement. The main complication of PTA is postoperative restenosis, which has not been widely reported in the literature, and the incidence of restenosis is 5.0% to 16.0%. Additional complications of PTA include TIA and stroke due to embolus dislodgement, vasospasm, intimal tear, arterial entrapment, and hematoma formation.
(2) Carotid artery stenting implantation PTA for stenosis has achieved certain results, but there are still problems of intraoperative intimal tear, postoperative vascular elastic retraction and restenosis due to.
(i) For eccentric plaques, the balloon support is only in the arterial wall opposite to the eccentric plaque, so the filling balloon cannot tear the eccentric plaque, and as a result, the dilated segment of the vessel will undergo elastic retraction after removal of the filling balloon;
(ii) The high restenosis rate of simple balloon dilatation is due to elastic retraction in the early stage and further development of atherosclerosis in the later stage;
(iii) For severe circumferential calcified plaque, dilation requires higher pressure and is prone to the formation of arterial entrapment. In contrast, the implantation of carotid artery stents can cover and tightly adhere to the vessel wall of the treated segment, close the entrapment caused by balloon dilation, and limit the contact between the artery and the material causing intimal hyperplasia within the circulating blood, thus improving the efficacy and reducing the incidence of restenosis. Indications for carotid stenting In 1998, the American College of Cardiology proposed the following principles for the management of carotid stenosis, which can be used as a reference for carotid stenting.
(1) Carotid stenosis (70% to 99%) with ipsilateral symptoms of stenosis is indicated for CE;
②Carotid stenosis (30%-69%) with symptoms of cerebral ischemia ipsilateral to the stenosis may be considered for CE treatment, but has not yet proven beneficial;
(iii) Carotid stenosis (0%-29%) with symptoms ipsilateral to the stenosis is not beneficial for CE treatment;
④For asymptomatic carotid stenosis (60% to 99%), CE is beneficial. Currently, the technical success rate of carotid artery stenting is greater than 98%, the complication rate is 2% to 6%, and the mortality rate is <1%, indicating that carotid artery stenting may be safe and effective in the treatment of carotid stenosis. However, the clinical efficacy of internal carotid artery stenting depends not only on the immediate efficacy and complication rate, but also on the long-term efficacy to determine the value of stenting in the treatment of carotid artery disease. Several multicenter, randomized, prospective, controlled clinical trials of carotid stenting versus CE for the treatment of carotid stenosis are currently underway, and more definitive conclusions are expected soon. Complications of carotid artery stenting.
(i) Postoperative restenosis rate <5%;
②Low incidence of stent deformation, collapse, and displacement;
(3) Other complications such as vasospasm, stroke, and hematoma formation are similar to PTA. In addition, in recent years, in order to reduce the incidence of TIA and cerebral embolism caused by embolus dislodgement during carotid artery stenting and to improve the safety of the operation, intraoperative cerebral protection devices have been used in clinical practice. The device can prevent the debris dislodged from the vessel wall during the operation from entering the skull with the blood flow and reduce the incidence of intraoperative cerebral embolism, and its long-term efficacy needs to be further confirmed.
(3) Comparison of PTA, carotid artery stenting and CE The effectiveness of CE has been demonstrated in several large clinical trials, but it also has certain limitations.
(1) Some patients require general anesthesia, and many patients cannot tolerate the procedure;
②The procedure is only applicable to lesions limited to the extracranial segment of the carotid artery;
(3) The procedure has certain complications.
PTA and carotid artery stenting have the following advantages over CE.
(1) General anesthesia is not required and can be tolerated by some patients with severe co-morbidities;
②The lesion may not be limited to the extracranial carotid artery;
③Small trauma and short operation time;
④The carotid artery, vertebral artery and coronary artery can be treated simultaneously.
PTA and carotid artery stenting also have some problems.
(i) Although the stenosis is improved, the potential source of emboli is not eliminated;
(ii) Most reports of carotid PTA and stenting implantation are small in size, with short follow-up periods, and long-term outcomes await further validation in randomized, large-scale clinical trials.
In conclusion, each of the three treatment approaches has its own advantages and disadvantages and should be further investigated to enrich the treatment of carotid artery stenosis disease.