OBJECTIVE: To evaluate the application of carotid endarterectomy (CEA) in the treatment of patients with moderate and severe stenosis of bilateral carotid arteries. METHODS: The clinical data of 82 patients with moderate or severe bilateral carotid artery stenosis admitted to Peking Union Medical College Hospital from January 2006 to December 2009 were retrospectively analyzed, of which 64 cases of unilateral CEA and 18 cases of bilateral CEA. RESULTS: A total of 100 CEAs were performed in the 82 patients, carotid artery patching was used in 92 cases, and endovascular flow tubes were used in 94 cases, and all of which were completed successfully. 76 cases patients recovered successfully; 2 cases developed myocardial ischemia and myocardial infarction; 1 case died due to massive cerebral infarction; 3 cases developed over-perfusion, 1 of which eventually led to cerebral hemorrhage. 76 (96.2%) of the 79 patients who completed the follow-up did not have cerebral ischemia related to the carotid artery on the operated side, 1 case was found to have mild restenosis on the operated side, and 2 cases developed neurological dysfunction. CONCLUSION: CEA should be performed in patients with moderate or severe bilateral carotid stenosis as long as the indications are clear. Patients with carotid stenosis are often combined with contralateral lesions. In patients with bilateral carotid stenosis, if the degree of stenosis of the opposite side of the carotid artery is less than 50%, and the hemodynamic indexes of the contralateral side of the carotid artery are almost unaltered, then carotid endarerectomy (CEA) is more effective than unilateral lesions. There is no significant difference between this procedure and unilateral lesions. For patients with contralateral stenosis of more than 50%, it has been shown that symptomatic patients with more than 50% stenosis and asymptomatic patients with more than 70% stenosis benefit from CEA, and a small number of scholars have suggested the necessity of surgery in asymptomatic patients with a stenosis of 50% to 70%. In this study, we evaluated the application of CEA in the treatment of patients with moderate and severe stenosis of bilateral carotid arteries, and summarized the treatment strategies and precautions for CEA of bilateral carotid arteries with a view to providing a reference for future clinical treatment. For patients with moderate or severe bilateral carotid artery stenosis, due to the restriction of bilateral carotid artery blood flow, the brain tissue itself is in an ischemic state, intraoperative, especially after the 1st operation to clamp the carotid artery to further reduce the intracranial blood supply, and the contralateral side of the compensation is not enough, which may lead to severe hypoperfusion or even cerebral infarction; and the stenosis resolution after the occurrence of the chances of over-perfusion is also significantly higher, the surgical risk is higher, the early report tends to be internal medicine Early reports favored medical treatment. However, with the application of intraoperative real-time monitoring and diversion technology and the improvement of surgical techniques, it is now believed that as long as attention is paid to monitoring blood pressure changes during the operation and good cerebral protection, serious stenosis or even occlusion of the contralateral carotid artery should not be a contraindication to CEA.Taylor et al. concluded that perioperative stroke and death in CEA is not related to whether the contralateral carotid artery is stenosed or occluded, and that the indications for CEA are not affected by the status of the contralateral carotid artery. Influence. In this study, all 82 patients with bilateral carotid artery stenosis of more than 50% had surgical indications that were also unaffected by contralateral lesions, and the stroke and mortality rate at 30 d postoperatively was 2.4%, which was lower than the standard of 3% to 6% set by the American Heart Association. Because the clinical presentation of patients with bilateral carotid artery stenosis is complex, with unilateral symptoms, bilateral symptoms, or no symptoms at all, the clinician needs to consider which side should be treated first. The author’s experience is that for patients with unilateral symptoms, the carotid artery on the responsible side should be treated first; if the stenosis of the opposite side of the carotid artery is >70% or the plaque is obviously unstable, then the carotid artery should be treated in the second phase; for patients with symptoms on both sides of the carotid artery, the carotid artery on the symptomatic side should be treated first in the first phase and the stenosis should be treated in the second phase. If the responsible side cannot be determined or the patient’s symptoms are typical and the degree of stenosis is similar, the dominant hemisphere is prioritized. The safety of CEA surgery has always been the focus of vascular surgeons, and the American Heart Association requires that the perioperative stroke/mortality rate for symptomatic carotid stenosis should be controlled at less than 6%, and that for asymptomatic carotid stenosis should be controlled at less than 3%. In patients with bilateral carotid artery stenosis, especially in patients with severe bilateral carotid artery stenosis, the blood flow in the distal part of the stenotic vessel slows down, the perfusion of the brain tissue on the same side decreases, the lack of collateral circulation from the contralateral side, and the contralateral side has a poor compensatory ability, so any small hemodynamic changes will cause irreversible ischemic injury to the brain tissue. Intraoperative clamping of the carotid artery may lead to ipsilateral cerebral perfusion reduction, resulting in an increased incidence of cerebral ischemia during surgery. Since the blood supply of the contralateral hemisphere may also need to be compensated by the operated side, this ischemia may even involve both hemispheres, with even more serious consequences. Therefore, intraoperative monitoring should be strengthened in this group of patients to understand the intracranial hemodynamic situation in real time and deal with it in time. The author’s experience is to routinely place a diversion tube intraoperatively and use TCD to monitor the middle cerebral artery blood flow velocity in real time to assess the intracranial blood supply. Whether and under what circumstances a diversion tube should be placed in CEA has long been controversial. The use of carotid artery shunts has the advantages of shortening the duration of cerebral ischemia, reducing the pressure on the operator, and facilitating medical teaching, but it also has the disadvantages of increasing the risk of embolization and the difficulty of operation, and prolonging the operation time. In patients with carotid stenosis with high ischemic risk, most scholars still support the establishment of intraoperative diversion, and Halsey’s study found that the establishment of diversion can significantly reduce the incidence of perioperative stroke in patients with high ischemic risk. In this study, diversion was routinely established intraoperatively in 82 patients (6 of which were unsuccessful due to high anatomical position), and the incidence of perioperative stroke was lower than international standards. TCD, as a noninvasive, simple, and reproducible cerebral blood flow monitoring technique, can monitor the blood flow of the MCA on the clamped side in real time, reflecting the changes in MCA blood flow before and after clamping in a timely manner, and indirectly suggesting the cerebral perfusion situation on the clamped side, which can help the operator discover intraoperative hypoperfusion in a timely manner and provide early warning of postoperative overperfusion. In this study, intraoperative TCD monitoring was routinely used in all patients with bilateral carotid stenosis to observe the changes in MCA blood flow velocity before and after CEA, and combined with the patients’ clinical symptoms and CT or MRI examinations, to assess the risk of perioperative hypoperfusion or overperfusion and to guide the actual clinical treatment. Intraoperatively, the author found that in patients with bilateral carotid artery stenosis, the ipsilateral MCA blood flow velocity decreased significantly after clamping the carotid artery (greater than 50% on average), suggesting that the incidence of cerebral hypoperfusion greatly increased during carotid artery clamping, further indicating that a diversion tube should be placed intraoperatively. Whether bilateral carotid artery severe stenosis can be treated with simultaneous or short-term bilateral CEA is still controversial. Simultaneous surgery avoids secondary anesthesia, reduces the traumatic stress of surgical operation and patient psychology, and enables early treatment of diseased vessels to reduce the potential risk of cerebral infarction. However, considering the high incidence of postoperative neurological complications, myocardial infarction and hyperperfusion syndrome, most scholars do not support simultaneous bilateral CEA, especially if the simultaneous surgery damages the bilateral recurrent laryngeal nerves, the consequences will be disastrous. Staged CEA, on the other hand, has been shown to be a safe and effective therapeutic measure. A certain amount of time is needed between the two surgeries to allow the patient to recover from the surgical blow while the intracranial blood vessels are able to adapt to the new environment after the opening of blood flow on one side. Because the brain of patients with carotid artery stenosis is chronically hypoperfused, the small arteries in the brain are extremely dilated, and the cerebral vascular autoregulation mechanism is impaired. Once the carotid artery is opened, the blood flow of the internal carotid artery increases greatly while the small blood vessels in the brain cannot contract and regulate accordingly, which can cause the blood flow rate of the intracranial artery on the same side to continue to increase, resulting in the occurrence of over-perfusion syndrome, and in severe cases, it may even lead to cerebral hemorrhage and death. Generally speaking, 1 week after surgery is the dangerous period of overperfusion, but a small number of patients can continue up to 4 weeks. Therefore, in order to avoid the dangerous period of postoperative hyperperfusion after CEA, the interval between bilateral surgeries should be at least 4 weeks. Of course, the time interval between bilateral procedures should not be too long. In particular, those with extreme stenosis (>95%) and delayed distal blood flow are likely to be lost if not operated on early.Rodriguez-Lopez et al. in a study of 77 patients who underwent bilateral CEA within a 4-d period found that the perioperative rates of TIA and stroke were 2.6 and 0.7%, respectively, with no significant increase in the incidence of surgery relative to unilateral lesions.Dimakakos et al. concluded that one-stage bilateral surgery could be considered in patients with bilateral symptomatic carotid stenosis, combined with intraplaque hemorrhage or bilateral near-occlusive lesions. In this study, 18 patients underwent bilateral CEA, 10 of whom were operated at 2-week intervals and 4 at 4-week intervals; 4 others underwent CEA because of the development of contralateral symptoms six months after the operation; all of them recovered uneventfully from both operations.