7/5/23, 11:36 AM Carotid endarterectomy - UpToDate Official reprint from UpToDate www.uptodate.com 2023 UpToDate, Inc. and/or its affiliates. All Rights Reserved. Carotid endarterectomy : Jeffrey Jim, MD, MPHS, FACS : John F Eidt, MD, Joseph L Mills, Sr, MD, Scott E Kasner, MD : Kathryn A Collins, MD, PhD, FACS All topics are updated as new evidence becomes available and our peer review process is complete. Literature review current through: Jun 2023. This topic last updated: Nov 14, 2022. INTRODUCTION Treatment aimed at carotid atherosclerotic lesions may be beneficial for symptomatic or asymptomatic patients. This topic will review the preoperative evaluation and surgical technique of carotid endarterectomy (CEA). The indications for carotid revascularization and perioperative stroke risk assessment for patients with carotid atherosclerosis are discussed elsewhere. (See "Management of asymptomatic extracranial carotid atherosclerotic disease" and "Management of symptomatic carotid atherosclerotic disease".) Carotid artery stenting is also discussed separately. (See "Overview of carotid artery stenting".) CAROTID ATHEROSCLEROTIC DISEASE The effectiveness of CEA in the management of selected patients with symptomatic or asymptomatic carotid atherosclerotic disease has been established by large randomized clinical trials. The specific indications for CEA are discussed in detail elsewhere. (See "Management of asymptomatic extracranial carotid atherosclerotic disease", section on 'Carotid endarterectomy' and "Management of symptomatic carotid atherosclerotic disease", section on 'Patients appropriate for CEA'.) Special considerations Bilateral carotid stenoses Some patients have varying degrees of bilateral carotid disease. No randomized clinical trials have evaluated the effectiveness of bilateral CEA for such patients. https://www.uptodate.com/contents/carotid-endarterectomy/print 1/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate However, bilateral carotid occlusive disease appears to increase the risk for complications during and after unilateral CEA (whichever of the two carotids is treated first) [1-5]. In a follow-up analysis of the North American Symptomatic Carotid Endarterectomy Trial (NASCET), the risk of stroke was significantly increased for a severely stenosed ipsilateral carotid artery associated with an occluded contralateral carotid artery [4]. In spite of higher perioperative morbidity in the presence of an occluded contralateral artery, the longer-term outlook for patients who had endarterectomy performed for a recently symptomatic, severely stenosed ipsilateral carotid artery was better compared with medically treated patients. The impact of bilateral disease appears to be greater for CEA compared with carotid stenting. In a systematic review and meta- analysis, patients with contralateral carotid occlusion had a significantly higher rate of cerebral events and death for CEA compared with carotid artery stenting [5] The impact of severe contralateral carotid artery stenosis or occlusion on the benefit and risk of unilateral CEA in patients with symptomatic and asymptomatic disease is discussed in more detail separately. (See "Management of symptomatic carotid atherosclerotic disease", section on 'Factors influencing benefit and risk'.) A combined approach (ie, bilateral repair during a single operation) is generally contraindicated due to the risks associated with respiratory compromise secondary to neck hematomas or recurrent laryngeal nerve injury, frequent difficulty with blood pressure control after manipulation of the carotid sinus, and concerns about cerebral hyperperfusion syndrome and the unknown effect of bilateral cerebral ischemia (although temporary). (See 'Perioperative morbidity and mortality' below.) When the extent of contralateral carotid disease is sufficiently severe to warrant bilateral CEA, most surgeons use a staged approach. When one side is symptomatic and the other asymptomatic, the symptomatic lesion is generally addressed first and the asymptomatic side addressed once the patient has recovered from the first CEA. If both sides are asymptomatic and of similar severity, the lesion supplying the dominant hemisphere is addressed first. When one lesion is significantly worse than the other and both are asymptomatic, the lesion of greater severity is addressed first and the second later as a staged procedure. Vocal cord paralysis following the first procedure should be excluded by otolaryngologic examination prior to performing the second procedure. (See 'Otolaryngologic examination' below.) Tandem proximal lesions Patients with internal carotid artery or carotid bifurcation disease can present with multilevel atherosclerotic disease involving the innominate artery or proximal https://www.uptodate.com/contents/carotid-endarterectomy/print 2/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate common carotid artery. Clinicians often prefer to combine treatment of these tandem lesions at the time of CEA. However, combined procedures are associated with a higher periprocedural risk compared with CEA alone. In an analysis of 404 patients undergoing CEA combined with proximal endovascular interventions compared with 66,115 patients undergoing CEA alone, patients undergoing a combined procedure had higher rates of perioperative stroke (3 versus 1.4 percent) and higher 30-day stroke and death rates (3.5 versus 1.8 percent). The increased risk was seen only in symptomatic patients; outcomes were similar for patients who were asymptomatic. These data suggest the need for caution when considering a combined approach [6]. In a systematic review, the pooled technical success rate for treating tandem lesions was high (99.8 percent), and pooled morbidity and mortality were as follows: death (1.5 percent), stroke (2.6 percent), combined stroke/death (3.3 percent), and myocardial infarction (3.2 percent) [7]. This study provided some insight on the optimal sequence for a combined procedure. For those in whom CEA was performed first, the risk of perioperative stroke was higher compared with those in whom the proximal intervention was performed first (5.7 versus 0 percent), suggesting that proximal stenting should be done prior to CEA. Distal lesions The data evaluating concomitant CEA with distal endovascular intervention are limited. The use of the term "distal intervention" can refer to treatment of a truly distinct lesion (eg, distal internal carotid artery) away from the carotid bifurcation. However, these combined procedures can also refer to the use of endovascular techniques to salvage complications caused by CEA (such as dissection or inadequate distal endpoint). In an analysis of 327 patients undergoing CEA combined with a distal endovascular intervention compared with 105,192 isolated CEA cases, patients undergoing a combined procedure had higher rates of perioperative stroke and mortality for both asymptomatic and symptomatic patients. However, this study was limited in determining if the distal intervention was planned preoperatively or performed as a salvage maneuver during CEA [6,8]. Carotid endarterectomy prior to other procedures Carotid intervention prior to other high-risk surgical procedures in patients with carotid artery stenosis is rarely needed, and a decision to proceed should be individualized depending upon the clinician's best estimate of the risk of perioperative stroke. Coronary artery bypass surgery Neurologic complications are second only to heart failure as a cause of morbidity and mortality following cardiac surgery. New stroke or transient ischemic attack occurs in approximately 3 percent of patients following coronary artery bypass grafting. As a result, CEA is often considered in conjunction with coronary artery bypass grafting in patients with significant carotid stenosis. However, there have been no trials examining the use of CEA in patients having coronary artery bypass grafting. https://www.uptodate.com/contents/carotid-endarterectomy/print 3/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate The indications for, timing of, and method of carotid revascularization in conjunction with coronary artery bypass grafting is discussed in detail elsewhere. (See "Coronary artery bypass grafting in patients with cerebrovascular disease", section on 'Prophylactic carotid intervention'.) General surgery The incidence of stroke appears to be lower following general (nonvascular) surgical procedures than following cardiac surgery, with a reported incidence in patients undergoing general anesthesia of less than 0.5 percent [9-11]. The risk may be slightly higher (1 percent) in asymptomatic patients with a carotid bruit who undergo general surgery [12]. There have been no randomized trials examining CEA in patients with carotid stenosis prior to general surgery. A retrospective review suggests that CEA is probably not warranted in most patients with asymptomatic carotid disease to lower their risk of perioperative stroke as a complication of their anticipated general surgical procedure [13]. This study was a chart review of 284 patients who had undergone nonvascular surgery requiring general anesthesia and had preoperative carotid ultrasound. While a previous history of stroke or transient ischemic attack, a carotid bruit, or both were present in 250 patients, all were considered to have asymptomatic carotid stenosis [14]. Ten of 284 patients (3.5 percent) had perioperative ischemic strokes within 30 days of the index procedure, and 8 of 224 (3.6 percent) with >50 percent carotid stenosis had an ipsilateral perioperative stroke (bilateral lesions were present in three patients). While this stroke risk exceeds that of the general population and of patients with carotid bruits, the increased risk appears to be insufficient to mandate CEA for asymptomatic carotid stenosis in the general surgical population. Major peripheral vascular procedures Although there are no trials of CEA prior to abdominal aortic aneurysm repair or other major peripheral vascular procedures, many vascular surgeons support performing CEA in those patients with appropriate indications for CEA, in anticipation of a major vascular procedure that may involve significant hemodynamic fluctuations. Endarterectomy in patients with intracranial aneurysm Ipsilateral intracranial aneurysms that are distal to a cervical internal carotid artery stenosis may be susceptible to sudden hemodynamic changes associated with CEA leading to aneurysm rupture [15]. On the other hand, surgical clipping of an aneurysm distal to a severe internal carotid stenosis may increase the risk of ischemic stroke. Unfortunately, data are too sparse to allow firm conclusions as to which problem should be treated first. However, caution is advised if CEA is performed in this setting, especially if the https://www.uptodate.com/contents/carotid-endarterectomy/print 4/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate ipsilateral aneurysm is 7 mm in diameter or if there is a history of subarachnoid hemorrhage from another aneurysm. (See "Unruptured intracranial aneurysms".) CONTRAINDICATIONS The only absolute contraindication to CEA is asymptomatic complete carotid occlusion. When an internal carotid occlusion occurs, thrombus propagates distally and intracranially to at least the first branch of the internal carotid artery, which is the ophthalmic artery. This precludes achieving an endpoint for a CEA performed at the carotid bifurcation in the neck. Whether it is appropriate to perform carotid revascularization for acute symptomatic carotid occlusion is discussed elsewhere. (See "Management of asymptomatic extracranial carotid atherosclerotic disease", section on 'Occlusion' and "Management of symptomatic carotid atherosclerotic disease".) Relative contraindications The following conditions may increase the risk of local or systemic complications and may support the use of alternative treatments such as medical management and/or carotid angioplasty and stenting [16]: History of prior neck irradiation resulting in "woody fibrosis" of the skin and subcutaneous tissues Presence of tracheostomy Prior radical neck dissection with or without radiation Contralateral vocal cord paralysis from prior endarterectomy Atypical lesion location, either high or low, that is surgically inaccessible Severe recurrent carotid stenosis Unacceptably high medical risk (eg, unstable cardiac status) (see 'Risk factors for poor outcome' below) Patients with these conditions may be candidates for carotid artery stenting. (See "Overview of carotid artery stenting".) PREOPERATIVE EVALUATION https://www.uptodate.com/contents/carotid-endarterectomy/print 5/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate A thorough vascular history and physical examination are essential components of the evaluation of a patient being considered for CEA. A search can be made for evidence of atherosclerotic disease elsewhere, including abdominal aortic aneurysm and peripheral artery disease. The cost effectiveness and medical benefit of screening under such circumstances is unknown. (See "Screening for abdominal aortic aneurysm" and "Noninvasive diagnosis of upper and lower extremity arterial disease" and "Atrial fibrillation in patients undergoing noncardiac surgery".) Risk factors for poor outcome Identification of risk factors for morbidity and mortality associated with CEA is important to avoid surgery in patients who may face an unacceptably high risk for endarterectomy. Advances in perioperative management have led at least some surgeons to conclude that among patients with appropriate indications for CEA, the proportion of patients with an unacceptable surgical risk is extremely small and continues to shrink. Modifications in surgical practice, refinement of anesthetic techniques and alternatives, the use of vasoactive medications in the perioperative period, and the declining use of routine preoperative contrast angiography (risk for acute kidney injury) may be responsible for the observed reduction in perioperative complication rates [17]. For patients at high risk for general anesthesia, regional anesthesia is an alternative that has equally good perioperative outcomes [18]. (See 'Anesthesia' below.) The following characteristics have each been associated with an increased risk of poor outcome (eg, stroke, myocardial infarction, death) at 30 days after CEA in some, but not all, studies [16,19- 37]. Later database reviews support the listed risk factors [29,30]. Older age (>70 years in one and 80 years in other studies) Severe heart disease Severe pulmonary dysfunction Renal insufficiency or failure Stroke as the indication for endarterectomy Anatomic issues, including limited surgical access, prior cervical irradiation, prior ipsilateral CEA, and contralateral carotid occlusion (see 'Relative contraindications' above) Among patients already selected to undergo CEA, there is no convincing evidence that female sex is a significant risk factor for adverse outcomes [38-43]. However, in a large database review from the American College of Surgeons National Surgical Quality Improvement Program of over 100,000 patients who underwent carotid intervention (104,412 CEA, 2156 carotid artery stenting) https://www.uptodate.com/contents/carotid-endarterectomy/print 6/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate between 2005 to 2017, the rate of postoperative neurologic complications was higher for females compared with males in both the asymptomatic and symptomatic cohorts. Although the specific patient factors that increase perioperative risk following CEA are debated, patients deemed to be at high risk have worse long-term outcomes following CEA [16,25,44]. In a retrospective review that compared 323 patients at high risk (anatomic or pathophysiologic) with 453 patients at normal risk, differences in perioperative outcomes were not significant [16]. However, two-year survival was worse in high-risk patients. Medical risk assessment Cardiac evaluation should be considered selectively since patients undergoing CEA are most likely to have morbidity related to coronary heart disease. This evaluation may be performed with exercise stress testing, dobutamine echocardiography, dipyridamole imaging, or, when warranted, coronary catheterization [45,46]. However, there is no evidence that immediate cardiac intervention alone reduces perioperative procedural risk of stroke or death for CEA. (See "Evaluation of cardiac risk prior to noncardiac surgery".) Preoperative chest radiography is generally not warranted for most patients undergoing elective surgery. However, a chest radiograph for most patients prior to CEA may be justified due to the association of carotid atherosclerosis with smoking and coronary heart disease [47]. (See "Preoperative medical evaluation of the healthy adult patient", section on 'Chest radiographs' and "Overview of established risk factors for cardiovascular disease".) Preoperative imaging Patients suspected of having carotid atherosclerosis are typically evaluated with carotid duplex ultrasound as the initial test to assess the severity and extent of carotid stenosis. Other useful noninvasive methods to assess the degree of stenosis of the internal carotid artery include computed tomography angiography, magnetic resonance angiography, and contrast-enhanced magnetic resonance angiography. The utility of these noninvasive methods and cerebral angiography in the initial evaluation of carotid stenosis is discussed in detail separately. (See "Evaluation of carotid artery stenosis".) In patients with a hemodynamically significant atherosclerotic lesion identified on duplex ultrasound, it remains controversial if further imaging is needed prior to endarterectomy in asymptomatic patients to verify the degree of stenosis or further evaluate arterial anatomy. Carotid duplex Prior to performing CEA in asymptomatic patients, we obtain a duplex ultrasound within one to two weeks of elective CEA to be certain that the carotid artery has not occluded, which contraindicates CEA. Some surgeons may feel the sensitivity of carotid duplex at their institution is not sufficient to reliably determine the degree of internal carotid artery stenosis or to rule out occlusion [48,49]. https://www.uptodate.com/contents/carotid-endarterectomy/print 7/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate In support of this point of view is a lack of uniformly applied, prospectively validated criteria in some settings for quantifying the degree of internal carotid artery stenosis with duplex ultrasound. However, there are disadvantages, risks, and costs associated with other imaging modalities including catheter-based angiography; magnetic resonance angiography, which tends to overestimate the degree of stenosis; and computed tomographic angiography, which may underestimate the degree of stenosis [50-52]. (See "Evaluation of carotid artery stenosis".) Experts in carotid ultrasound developed consensus-based recommendations for using duplex- derived velocity and imaging parameters to quantify internal carotid artery stenosis with duplex ultrasound [53]. These state that the utility of the recommendations should be verified in individual vascular laboratories, and the suggested parameters should not replace duplex parameters that are locally documented to provide accurate assessment of carotid stenosis. As such, it may be reasonable for the surgeon who has access to a certified vascular laboratory with ongoing quality assurance programs and staffed by registered vascular technologists to use duplex ultrasound as a sole imaging modality of the cervical internal carotid artery prior to performing CEA. Brain imaging In the symptomatic patient, the preoperative evaluation should also include computed tomography or magnetic resonance imaging of the brain to assess the degree of cerebral infarction, if any, and to exclude other disorders that might be responsible for symptoms (eg, subdural hematoma, tumor). The added risk and costs of catheter-based arteriography probably outweigh the benefit of obtaining more anatomic detail. The incidence of stroke associated with routine arteriography was 1.6 percent in the Asymptomatic Carotid Atherosclerosis Study (ACAS) , although this risk was lower than in other reports [54]. However, arteriography is the gold standard for evaluating intracranial atherosclerotic disease, which is present to some degree in many patients with stenosis of the extracranial internal carotid artery [55-57]. In an analysis of a subset of patients from North American Symptomatic Carotid Endarterectomy Trial (NASCET), the relative risk of stroke associated with intracranial atherosclerotic disease in medically treated patients was 1.3 for extracranial stenosis <50 percent and 1.8 for extracranial stenosis 85 to 99 percent [57]. CEA reduced this risk, suggesting that detection of intracranial atherosclerotic disease, particularly in those with moderate extracranial carotid stenosis, may help stratify patients into a group that is more likely to benefit from CEA. Of the available noninvasive tests (ie, transcranial Doppler, computed tomographic angiography, magnetic resonance angiography), CTA may be more accurate for identifying intracranial large artery stenosis. (See "Intracranial large artery atherosclerosis: Epidemiology, clinical manifestations, and diagnosis", section on 'Diagnostic evaluation' and "Evaluation of carotid artery stenosis".) https://www.uptodate.com/contents/carotid-endarterectomy/print 8/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate Otolaryngologic examination Otolaryngologic examination, which may include laryngoscopy, should be performed in patients who have a residual vocal disturbance (tone change, hoarseness) after a prior neck surgery (eg, CEA, thyroid surgery). (See "Hoarseness in adults", section on 'Neurologic dysfunction' and "Complications of carotid endarterectomy", section on 'Nerve injury'.) PREOPERATIVE PREPARATION Medication management Antiplatelet therapy Aspirin Antiplatelet therapy with aspirin reduces the risk of stroke of any cause in patients undergoing CEA [58,59]. In addition, lower-dose aspirin (81 to 325 mg daily) is more effective than higher-dose aspirin (650 to 1300 mg daily). In a randomized trial involving 232 patients, aspirin (75 mg daily) or placebo treatment was started preoperatively and continued for six months [60]. Patients assigned to aspirin had significantly fewer strokes at one month and six months compared with those assigned to placebo. However, this study was likely underpowered [61]. The ASA and Carotid Endarterectomy (ACE) trial randomly assigned 2849 patients scheduled for endarterectomy to aspirin at doses of 81, 325, 650, or 1300 mg daily [62]. Aspirin was started before surgery and continued for three months. At three-month follow- up, the primary endpoint (stroke, myocardial infarction, vascular death) was significantly reduced in the lower-dose (81 or 325 mg daily) aspirin group compared with the higher- dose group (6.2 versus 8.4 percent). Consensus guidelines from the American Academy of Neurology and the American College of Chest Physicians recommend aspirin for symptomatic and asymptomatic patients undergoing CEA [61,63]. We recommend starting aspirin (81 to 325 mg daily) prior to CEA and continuing indefinitely in the absence of contraindications. Although other agents are available, aspirin is the best studied antiplatelet agent following CEA, and aspirin alone is generally deemed adequate for postoperative management given that the carotid plaque has been removed. However, for patients who are allergic or sensitive to aspirin, clopidogrel can be used as an alternative agent. For those patients with atherosclerotic plaque elsewhere (eg, lower extremity), other agents or combinations may be favored for long-term secondary prevention of cardiovascular events. https://www.uptodate.com/contents/carotid-endarterectomy/print 9/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate Dual antiplatelet therapy or other regimens Without clear high-level data, any decision to use an agent other than aspirin or to proceed with dual antiplatelet therapy (DAPT) or triple antithrombotic therapy after CEA should be individualized and depends on the indications for antiplatelet therapy, clinical status, as well as operative findings [64-66]. (See "Prevention of cardiovascular disease events in those with established disease (secondary prevention) or at very high risk" and "Long-term antithrombotic therapy for the secondary prevention of ischemic stroke" and "Aspirin for the secondary prevention of atherosclerotic cardiovascular disease".) It may be reasonable to allow patients with chronically administered DAPT for other indications to continue these throughout the perioperative period. Most studies report an increased risk for bleeding with DAPT, but other outcomes are variable. In one trial of 102 patients undergoing CEA, rates of perioperative bleeding were similar for patients taking dipyridamole/aspirin (n = 39), dipyridamole/aspirin plus dextran (n = 30), or dipyridamole/aspirin plus clopidogrel (n = 33) [66]. In a database review from the Vascular Quality Initiative, 25 percent of patients (7059 of 28,683) undergoing CEA were on aspirin plus clopidogrel [67]. While DAPT significantly increased the risk of bleeding and reoperation after CEA, the risk for perioperative neurologic events was significantly reduced. In a later meta-analysis, operating times were shorter, and the incidence of neck hematoma, major bleeding, myocardial infarction, and perioperative (30 day) mortality was reduced for single antiplatelet therapy (125,850 patients) compared with DAPT (14,280 patients) [68]. In systematic review that included 11 studies involving 47,411 patients, 30 percent received DAPT and the remainder received aspirin only [69]. The rates of perioperative stroke were similar, but the risk of neck hematoma and reoperation for bleeding were increased. Long-term anticoagulation A decision to stop versus bridge long-term oral anticoagulation prior to CEA is individualized and made together with the patient's cardiologist or medical physician [70]. (See "Perioperative management of patients receiving anticoagulants" and "Coronary artery disease patients requiring combined anticoagulant and antiplatelet therapy".) Regardless of whether oral anticoagulation is continued or temporarily discontinued (with or without bridging anticoagulation), antiplatelet therapy (ie, aspirin or clopidogrel) is initiated prior to CEA in the manner discussed above. (See 'Antiplatelet therapy' above.) https://www.uptodate.com/contents/carotid-endarterectomy/print 10/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate Following CEA, if oral anticoagulation was temporarily discontinued, it is resumed and aspirin or clopidogrel initiated preoperatively is continued. Any new ischemic or bleeding episodes (or change in bleeding risk) should lead to a reevaluation of antithrombotic therapy. Statins The use of statins in symptomatic patients undergoing CEA may be associated with improved outcomes. In a retrospective observational study of 3360 CEAs, statin use was associated with reduced in-hospital mortality and combined in-hospital ischemic stroke or death (adjusted odds ratio 0.25, 95% CI 0.07-0.90 and 0.55, 95% CI 0.32-0.95, respectively), but in- hospital cardiac outcomes were not significantly improved [71]. A later, large database study reported similar results [72]. In contrast, statin use by patients with asymptomatic carotid stenosis was not associated with significantly different outcomes. Similar results were reported in another retrospective study involving 1566 patients with symptomatic and asymptomatic disease who received statins for at least one week before CEA [73]. These findings require confirmation in randomized clinical trials. Evidence is also emerging that statins may be of benefit in the perioperative period, and that this benefit might be lost if statins are discontinued. This issue is discussed elsewhere. (See "Perioperative medication management", section on 'Non-statin hypolipidemic agents'.) Sedative-analgesic medications Certain sedative-analgesic medications may be warranted to relieve preoperative anxiety. When an anxiolytic is chosen, a short-acting agent should be used, and it should be administered only after the patient's neurologic examination has been documented. (See "Anesthesia for carotid endarterectomy and carotid stenting".) Prophylactic antibiotics We recommend administration of antibiotics prior to CEA to control surgical site infection due to the frequent use of prosthetic material ( table 1) [74]. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults", section on 'Vascular surgery'.) SURGICAL ANATOMY AND PHYSIOLOGY Carotid artery The left common carotid artery originates from the aortic arch, whereas the right common carotid artery originates from the innominate artery ( figure 1). The common carotid artery divides into the internal carotid artery and external carotid artery typically at the level of the superior border of the thyroid cartilage corresponding to the C3/C4 disc space. The vagus nerve is posterior to the common carotid artery in most individuals, although it may be located anteriorly in 5 to 10 percent of cases. Cranial nerve or other nerve injuries can occur https://www.uptodate.com/contents/carotid-endarterectomy/print 11/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate during dissection, retraction, or clamp placement ( figure 2). (See "Complications of carotid endarterectomy", section on 'Nerve injury'.) External carotid artery The external carotid artery has multiple branches that supply the face and scalp and provide collateral circulation to the brain ( figure 3). These branches include (caudal to cranial) the superior thyroid, lingual, facial, ascending pharyngeal, occipital, posterior auricular, maxillary, and superficial temporal arteries. The ascending pharyngeal artery arises very near the bifurcation of the carotid artery. In one anatomic study, the ascending pharyngeal artery originated from the external carotid artery in 80 percent of specimens (56 percent medially, 44 percent posteriorly) [75]. In the other 20 percent, the ascending pharyngeal artery originated from the internal carotid artery (5 percent), carotid bifurcation (5 percent), occipital artery (5 percent), and a trunk common to the lingual and facial arteries (5 percent). Internal carotid artery The internal carotid artery normally has no branches in the neck ( figure 4). The cervical segment of the internal carotid extends from the carotid bifurcation until it enters the carotid canal anterior to the jugular foramen. The internal carotid artery runs cranially within the carotid sheath and lies posterior and lateral to the external carotid artery beneath the medial border of the sternocleidomastoid muscle. In its distal (cranial) course, it passes beneath the hypoglossal nerve, the digastric muscle, the stylohyoid muscle, the occipital artery, and the posterior auricular artery. More cranially, the styloglossus and stylopharyngeus muscles, the tip of the styloid process and the stylohyoid ligament, the glossopharyngeal nerve, and the pharyngeal branch of the vagus nerve separate the internal from the external carotid artery. Location and influence of the carotid baroreceptor Baroreceptors are stretch-sensitive mechanoreceptors that respond to alterations in blood pressure. The carotid sinus baroreceptors are located within the adventitia of the origin of the internal carotid artery and are innervated by the sinus nerve of Hering, which is a branch of glossopharyngeal nerve. In response to low blood pressure, the nerve fibers decrease their firing rates, stimulating the sympathetic nervous system and inhibiting the parasympathetic nervous system via a centrally acting mechanism. Carotid sinus reactivity may be altered in patients with carotid atherosclerosis. Patients display varying degrees of heart rate or blood pressure alterations during manipulation of the carotid bifurcation, carotid clamping, or postoperatively following CEA [76]. Endarterectomy, removal of atheromatous debris, and reconstruction of the carotid artery may increase tension on the carotid sinus baroreceptor, increasing its activity [77]. The opposite is also possible if damage to the carotid sinus or sinus nerve occurs. As an example, eversion endarterectomy requires division of the carotid artery, and as a result, the longitudinal fibers of https://www.uptodate.com/contents/carotid-endarterectomy/print 12/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate the carotid sinus nerve are transected. A study that measured baroreceptor sensitivity following CEA found increased sensitivity with conventional CEA and decreased sensitivity with an eversion technique [78]. Correspondingly, postoperative blood pressures were significantly increased for eversion compared with conventional CEA (systolic: 127, diastolic: 64, mean: 86; versus systolic: 111, diastolic: 55, mean: 75). Compensation over time occurs due to intact baroreceptor mechanisms from the contralateral side and aortic arch. (See 'Conventional versus eversion endarterectomy' below.) ANESTHESIA Carotid endarterectomy can be performed using local/regional anesthesia or general anesthesia. Ideally, surgical and anesthetic teams should be competent in both techniques because a patient might prefer, or there might be a medical reason to choose, one anesthetic technique rather than another [79]. In an analysis of 26,070 cases in the American College of Surgeons National Surgical Quality Improvement Program database, general anesthesia was used in 84.6 percent and regional anesthesia was used in 15.4 percent of cases [80]. In another study looking at over 75,000 cases, 8.9 percent were performed under local/regional anesthesia. CEA performed under general anesthesia was associated with twice the odds of in-hospital myocardial infarctions, four times the odds of acute congestive heart failure, 1.5 times the odds of hemodynamic instability, and 1.8 times the odds of staying in the hospital for >1 day. However, the authors noted that the overall risk of adverse cardiac events after CEA was overall low, which made the differences clinically irrelevant [81]. Local/regional anesthesia may be more beneficial for some patients but can be uncomfortable for the patient and may necessitate urgent conversion to general anesthesia or urgent shunt placement. (See "Anesthesia for carotid endarterectomy and carotid stenting", section on 'Selection of the anesthetic technique'.) Anesthetic choice The use of general anesthesia for CEA or performing awake carotid surgery with local anesthesia (with or without cervical block) is generally determined by surgeon preference and patient characteristics and preference. The available evidence suggests that the choice of anesthetic technique has no significant impact on clinically important outcomes after CEA. (See "Anesthesia for carotid endarterectomy and carotid stenting", section on 'Selection of the anesthetic technique'.) Assessing brain perfusion Although 80 to 85 percent of patients tolerate clamping of the carotid artery without consequence, the collateral circulation via the circle of Willis should be https://www.uptodate.com/contents/carotid-endarterectomy/print 13/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate assessed in all patients who do not undergo mandatory shunting. (See 'Preoperative imaging' above and 'Carotid shunting' below.) During local/regional anesthesia in cooperative patients, clinical assessments are made during the procedure by monitoring mental status, speech, and extremity function. Agitation, slurred speech, disorientation, and extremity weakness are indications for shunt placement. During general anesthesia, assessment of cerebral perfusion to determine which patients should receive a shunt can be accomplished with a variety of methods (eg, measurement of carotid stump pressure, transcranial Doppler, somatosensory evoked potentials, jugular venous oxygen saturation). The most commonly used methods are discussed in detail elsewhere. (See 'Carotid shunting' below and "Anesthesia for carotid endarterectomy and carotid stenting", section on 'Neuromonitoring modalities'.) SURGICAL TECHNIQUE Endarterectomy procedure General conduct of operation CEA is performed through a neck incision, either a longitudinal one along the anterior border of the sternocleidomastoid muscle or with a transverse incision in a skin crease at the level of carotid bulb. For the latter incision, preoperative imaging with ultrasound will guide the surgeon to the optimal placement of the incision. No significant differences between these approaches have been identified in terms of stroke, wound complications, or nerve complications [82]. The underlying platysma muscle and subcutaneous tissues are divided, the carotid sheath exposed, and the internal carotid artery is carefully identified and dissected. The extent of exposure of the artery is dependent upon the distribution of disease determined by intraoperative findings. Typically, dissection is needed from the common carotid artery to a point distal to the bifurcation of the internal carotid artery and external carotid artery that is beyond palpable internal carotid artery plaque to allow for clamping of normal soft artery. Following carotid dissection, the patient is systemically anticoagulated (heparin given as bolus, or using an alternative agent, as indicated). Monitoring the activated clotting time is not usually needed, owing to the short duration of carotid clamping, which is typically less than an hour. Carotid stump pressures can be obtained to help guide the need for shunt placement. The internal, common, and external arteries are clamped sequentially; the internal carotid artery is always clamped first to prevent embolization. A needle attached to a transducer is introduced into the common carotid artery. The clamp on the internal carotid artery is released and a https://www.uptodate.com/contents/carotid-endarterectomy/print 14/45 7/5/23, 11:36 AM Carotid endarterectomy - UpToDate waveform is obtained. Mean pressures greater than 30 to 50 mmHg imply adequate collateralization via the circle of Willis down the ipsilateral carotid artery. Lower stump pressures are an indication for shunt placement, and higher pressures are associated with stroke rates <0.5 percent [83]. Critics of this technique caution that pressures are only obtained after initial clamping and, therefore, represent a "snapshot" in time. In addition, the criteria above should be used with caution in patients who have suffered prior ipsilateral strokes (potential vulnerable penumbra surrounding the prior infarct) since there is a poor correlation between adequate perfusion pressures and outcomes in this setting. The accuracy of the pressure in the face of a preocclusive (string) lesion may also be questionable. (See 'Assessing brain perfusion' above.)