Abstract: Objective To investigate the value of integrated carotid ultrasonography and transcranial Doppler (TCD) in perioperative period of carotid endarterectomy (CEA). 
Methods The clinical data of 166 patients who received CEA due to carotid stenosis were retrospectively analyzed. In addition to digital subtraction angiography (DSA) and/or computed tomography angiography (CTA), carotid artery color Doppler ultrasound (referred to as carotid artery ultrasound) was also conducted to evaluate carotid artery stenosis and characteristics of plaques. Transcranial color-coded Duplex (TCCD) and TCD were carried out to determine the compensatory status of collateral circulation of the brain. TCD was used to monitor the peak systolic velocity (PSV) of bilateral middle cerebral artery (MCA) during the operation, and the blood pressure was regulated individually according to the changes of PSV, so as to decide whether to use CEA shunts to prevent the occurrence of cerebral hyperperfusion syndrome. Integrated carotid ultrasonography and TCD were used for reexamination and follow-up to evaluate the effect of CEA after the operation. 
Results Carotid artery stenosis and collateral circulation in all patients were evaluated through integrated carotid ultrasonography and TCD. Among them, there were 8 cases of subtotal occlusion of the internal carotid artery, 15 cases of stenosis rate ranging from 50% to 69% with clinical symptoms, 136 cases of stenosis rate ranging from 70% to 99% (including 4 cases of stent restenosis with stenosis rate ranging from 70% to 99%), and 6 cases of carotid web. Anterior communicating artery patency was present in 27 cases, posterior communicating artery patency in 38 cases, anterior-posterior communicating artery patency in 13 cases, and internal-external carotid artery collateral circulation was open in 42 cases, and no collateral artery opening in 9 cases, which was highly consistent with DSA or CTA results. Twenty-four cases underwent CEA with shunting. Among the patients who underwent CEA without a shunt, 6 cases of mild cerebral hyperperfusion syndrome and 1 case of mild cerebral infarction occurred after operation. Within 7 days after operation, 2 cases died, including 1 death from myocardial infarction and 1 death from sudden cardiac arrest. Internal carotid artery (ICA) occlusion occurred in one case who underwent ligation of ICA due to severe carotid artery stenosis with extracranial ICA aneurysm. ICA patency was found in all the other 163 patients in the first 6-month follow-up after operation. 
Conclusion The degree of carotid artery stenosis and the opening of collateral circulation assessed by integrated carotid ultrasonography and TCD were highly consistent with DSA. Integrated carotid ultrasonography and TCD can provide reliable information before, during and after CEA, improve the safety of surgery, and has important application value in the perioperative period of CEA. 

Key words: carotid stenosis, carotid endarterectomy, ultrasonography, Doppler, color