The high incidence of acute stroke, high disability rate, high death rate and high recurrence rate is a clinical issue that needs to be addressed in the prevention and treatment of cerebrovascular disease, and is receiving more and more attention from governments and the medical community, especially the neuroscience community. Studies have found that about 70% of cerebrovascular diseases are ischemic cerebrovascular diseases, and ischemic cerebrovascular diseases are mainly caused by the narrowing or occlusion of cerebral blood vessels. The literature reports that about 25% of ischemic strokes are related to stenosis or occlusion of the internal carotid artery. Atherosclerotic stenosis of the internal carotid artery may increase the risk of ischemic stroke through embolization or by causing hemispheric hypoperfusion.
I. Current status of treatment of cerebral artery stenosis
Interventional treatment of cerebral artery stenosis: symptomatic cerebral artery stenosis has been a difficult clinical treatment. Currently, its treatment is divided into 3 categories:
(1) pharmacological treatment;
(2) surgical treatment;
(3) interventional treatment.
Internal anticoagulation and antiplatelet therapy often fail to control stroke attacks; surgical intracranial-extracranial vascular anastomosis and endarterectomy are limited by various factors and are risky. In recent years, due to the development of safe and effective stent delivery and delivery tools and stents, the use of interventional therapy in cerebral atherosclerotic stenosis has gradually increased.
Treatment of cerebral artery stenosis
1. Cerebral angiography or cerebrovascular imaging must be performed before endovascular intervention for ischemic cerebrovascular disease.
The purpose is to understand the vascular status of the aortic arch, internal carotid artery system and vertebrobasilar artery system, and to determine whether there is cerebrovascular pathology and whether it is suitable for endovascular intervention. At present, the image effect of cerebral angiography is better than MRI or CT angiography in China, therefore, those who have the conditions should still choose cerebral angiography.
Cerebral angiography is a mature examination method with simple operation, little trauma, fast recovery and very rare complications. All patients suspected of having cerebrovascular lesions are suitable for cerebral angiography, such as: cerebral artery stenosis or occlusion, cerebral aneurysm, cerebrovascular malformation, etc.
2.The main indications for endovascular intervention for ischemic cerebrovascular disease are
(1) Cerebral artery stenosis:
At present, there is no pharmacological treatment for cerebral artery stenosis, surgery is highly injurious, and surgery for deep cerebral artery stenosis is difficult to implement. Therefore, endovascular intervention is currently the best treatment method. Endovascular interventions for cerebral artery stenosis have been done more frequently or in a more mature way for carotid artery stenosis and extracranial segment of vertebral artery stenosis. Endovascular intervention can also be performed for intracranial cerebral artery stenosis in hospitals that have the conditions to do so. Endovascular intervention for cerebral artery stenosis is basically based on stent implantation, which uses the elasticity of the stent to open up the narrowed artery.
Stent implantation for cerebral artery stenosis is a new technique that has been introduced in recent years. A survey of more than 5,000 carotid artery stenting (CAS) patients in Europe, the United States, and Asia showed that carotid artery stenting was significantly better than carotid endarterectomy. According to current data, CAS has the following advantages over carotid endarterectomy: no risk of cerebral nerve injury; treatment of lesions that are difficult to reach surgically, such as carotid stenosis in the intracranial segment; no need for general anesthesia, the patient’s neurological status can be observed at any time during the operation, and treatment can be terminated at any time in case of an accident; and rapid postoperative recovery.
Endovascular intervention is also suitable for carotid stenosis: if carotid stenosis is >70% and there are associated neurological symptoms. or there are imaging changes of brain parenchymal ischemia associated with the stenosis. Or for a small number of carotid artery stenosis <70%, but with significant associated symptoms, endovascular intervention can also be considered in hospitals where available.
This treatment is also indicated for stenosis of the extracranial segment of the vertebral artery: if symptoms of ischemia in the vertebrobasilar system or recurrent posterior circulation strokes, where medical anticoagulation or antiplatelet therapy is ineffective. or stenosis of >70% of the opening of one vertebral artery and dysplasia or complete occlusion of the other side. or bilateral vertebral artery opening stenosis >50%.
(2) Intra-arterial thrombolysis
The most effective treatment for acute arterial thrombotic cerebral infarction is thrombolytic therapy, and intravenous thrombolytic therapy can be used for those with onset within 3h. However, the effect of intravenous thrombolytic therapy is not sure for those with onset time more than 3h, and intra-arterial thrombolytic therapy can be used at this time.
Indications.
①The onset of arterial thrombosis is within 6h, which can be extended to within 24h of onset in some patients.
②Signs and symptoms of neurological impairment are present.
The advantages of using this method are: longer application time and faster thrombolysis than intravenous thrombolysis. The dissolution of the thrombus can be observed at the time of surgery.
(3) Precautions for endovascular intervention for ischemic cerebrovascular disease
Before the cerebral angiography and endovascular intervention, patients should have their blood drawn for routine blood tests, coagulation function, liver and kidney function, electrocardiogram and iodine allergy test, and fasting before the operation. It is generally recommended that at least 3 d of antiplatelet therapy, either oral aspirin or clopidogrel, should be given prior to stenting. Postoperative observation in the intensive care unit is required for about 24h. Patients undergoing stenting also need to continue antiplatelet therapy.
Intraoperative and postoperative complications may occur in a very small number of patients, mainly: puncture site infection, hematoma, femoral artery fistula and intimal tear, carotid sinus reaction, ischemic stroke, cerebral hemorrhage, and revascularization. As long as the preoperative preparation is adequate, the indications and contraindications are strictly mastered, the operation is carefully performed, and the postoperative observation and treatment are meticulous and timely, the occurrence of complications can be reduced.
(4) Prevention and treatment of several common complications
(1) Prevention and treatment of puncture site complications: strict disinfection of the operative area, routine broad-spectrum antibiotic sedation 30 min before surgery to prevent infection that may be caused by prolonged surgery. Hematoma at the puncture site, femoral artery fistula and endovascular tear are the main complications associated with puncture. During puncture, the guidewire should be inserted after ensuring complete entry of the puncture needle into the vessel, i.e., the guidewire should be inserted only when the blood flow is clear when the needle core is withdrawn, and the guidewire should be withdrawn immediately or slowly fed under fluoroscopy if resistance is felt during the upward movement of the guidewire. Hematoma at the puncture site is mainly due to incorrect postoperative compression, mainly because the compression site is low or too high. Correct compression and avoiding squatting, sitting, running and other activities for one week after surgery can avoid the occurrence of hematoma.
②Carotid sinus reaction: It is the most common complication during and after CAS surgery. It is mainly caused by the stimulation of pressure receptors at the bifurcation of the common carotid artery after balloon dilation or stent implantation and the enhancement of vagal impulses [3]. It is currently believed that the choice of stent diameter should preferably be close to the proximal diameter of the carotid artery, low-pressure balloon dilation of the stenosis, and routine administration of atropine 1 mg intravenously before balloon dilation can prevent complications.
(3) Hyperperfusion syndrome: It is caused by the sudden release of the stenosis and the expansion of the artery, resulting in a significant increase in blood flow. Patients mainly present with headache, nausea and vomiting and other symptoms of high cranial pressure, seizures, which may be accompanied by a significant increase in blood pressure and even cerebral hemorrhage. Once detected, blood pressure control, dehydration and cranial pressure lowering treatment are given immediately.
④Intracranial hemorrhage: It is the most dangerous complication of CAS and is an important cause of death. Intracranial hemorrhage can manifest as intracerebral parenchymal hemorrhage, subarachnoid hemorrhage, and subdural hematoma occurring probably due to hyperperfusion after percutaneous transluminal angioplasty and stenting (PTAS), but there may be other causes as well. Postoperative blood pressure should be kept as low as possible to reduce bleeding from hyperperfusion.
⑤ Ischemic stroke: In CAS, in patients with occlusion of the carotid artery on one side and high stenosis of the internal carotid artery on the other side, acute cerebral ischemia may result intraoperatively due to temporary blockage of carotid flow by balloon dilation; therefore, the duration of balloon dilation should be shortened. In addition, there is a possibility of generating emboli during each step of CAS, especially during stent implantation or balloon dilation that can easily induce thrombosis or cause plaque dislodgement, resulting in cerebral infarction. Performing CAS with a distal brain protection device can effectively reduce thromboembolic complications. Patients with intraoperative embolic symptoms are immediately angiographed and the distal vessel is found to be occluded. After angiography, 200,000 units of urokinase is slowly injected along the catheter and the angiography can be reviewed to observe whether the occluded vessel is recanalized. Routine postoperative treatment.
(6) Vasospasm: The stimulation of catheter, guidewire and contrast agent can lead to vasospasm. Prophylactic application of nimodipine during the procedure can reduce the morbidity.
(vii) Restenosis after PTAS: This includes 2 types, in-stent stenosis and end-stent stenosis, the latter being caused by kinking of the stent at the end of the internal carotid artery. the average time to develop a stenosis requiring re-treatment after CAS is 44 months. greater than 50% restenosis occurs in CAS, 0% at 6 months, 6% at 1 year, 35% at 2 years, and 56% at 3 years. schillinger et al. found that C-reactive protein and serum amyloid A were independent predictors of restenosis. Active prevention of risk factors may reduce restenosis.