Get an inside look at how Rutherford's Vascular Surgery approaches carotid endarterectomy — from indications and perioperative management to operative technique, cerebral protection, and shunting strategies.
Definitive, state-of-the-art guidance on vascular disease and its medical, surgical, and interventional management Order your copy today at elsevierhealth.com/9780443286179 From Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition Exclusive preview: Carotid Endarterectomy CHAPTER 84 Carotid Endarterectomy 1185 skin crease, usually 1 to 2 cm inferior to the angle of the jaw. If the incision is made too low, more cephalic exposure can be obtained by extending the skin crease incision posteriorly. If the incision is made too high, more caudal exposure can be obtained by extending the incision more anteriorly. Carotid Exposure Carotid exposure is described in Chapter 52. Manipulation of the carotid artery should be minimized because intraoperative embolization can result from careless handling. There are sev- eral key anatomic structures that merit emphasis. The external jugular vein lies deep to the platysma and is more commonly encountered with an oblique skin crease incision. The facial vein is identified crossing medially in the base of the wound and divided; sometimes it has an early bifurcation or trifur- cation, and multiple branches need to be ligated. The vagus nerve is identified in the carotid sheath, usually located pos- teriorly between the jugular vein and carotid artery, although in a minority of patients it may lie anteriorly. The common carotid artery (CCA) is controlled circumferentially with an umbilical tape and a Rummel tourniquet. The ansa cervicalis nerve should be identified; it usually lies medial to the distal CCA and identifying this nerve facilitates safe dissection of the carotid bifurcation and avoids injury to the hypoglossal nerve, which crosses medially from a superior to an inferior location (Fig. 84.2). The superior thyroid artery is controlled with a tie or plastic vessel loop and the external carotid artery (ECA) is controlled with a vessel loop. Finally, the ICA should be ex- posed and controlled with a vessel loop distal to the plaque, where the artery has a typical bluish appearance because of translucency of the vessel. During dissection of the carotid bi- furcation and its branches, one should avoid dissecting in the crotch of the carotid bifurcation to avoid injuring the carotid body to minimize hemodynamic instability and troublesome bleeding. If hemodynamic instability results, the carotid body can be gently injected with 1% lidocaine. Before clamping, the patient is administered 70 to 100 U/kg of heparin, which is allowed to circulate for 3 minutes. The ICA is clamped first to prevent the embolization that can result when the CCA or ECA is clamped. Care should be taken to make sure that the ICA is clamped on a normal portion of the artery distal to the plaque. If LA or intraoperative electroencephalography is used for selective shunting, a test clamp on the distal ICA should be applied for at least 3 minutes to check for changes in the neuro- logic examination or electroencephalographic (EEG) pattern. If such changes occur, the artery should be unclamped to allow reperfusion before reclamping and opening the carotid bifur- cation; opening the bifurcation and placing a shunt may take 2 to 3 minutes and should not be performed while the brain is already ischemic. However, unclamping the ICA introduces the potential for embolization from disrupted plaque. If carotid stump pressure is to be measured, clamps are placed on the CCA and the ECA, and a needle connected to a pressure line is placed into the distal CCA below the carotid bifurcation. Both clamping the CCA and placing the needle into the artery introduce the potential for embolization. Conventional Endarterectomy The conventional technique for CEA consists of a vertical arte- riotomy and closure usually by patch angioplasty. One should avoid making the incision too close to the flow divider at the ECA origin because this can distort the anatomy and make the closure more difficult (Fig. 84.3). The endarterectomy begins in the CCA in the plane be- tween the media and the adventitia. The proximal endpoint in the distal CCA is established and the plaque is trimmed in that location in a beveled manner. The endarterectomy is continued into the orifice of the ECA, first with a Freer elevator and then with a fine clamp that is passed up into the ECA in the plane of the endarterectomy and spread to further mobilize the plaque away from the adventitia in the 6-, 9- , and 12-o’clock posi- tions; it is usually difficult to pass the clamp in this plane at the 3- o’clock position next to the flow divider. The vessel loop on the ECA is released transiently while the plaque is everted from within the ECA. The endpoint of the plaque is inspected; an ideal endpoint is gradually tapering and feathered (Fig. 84.4). All loose bits of intima and media in the orifice of the ECA should be removed, although others believe that endarterec- tomy of the ECA may be neglected without compromising results. 58 A technically perfect endpoint in the ICA is critical. Occa- sionally, special maneuvers may be required to expose the distal ICA to extend the arteriotomy to achieve an acceptable end- point, as seen in Fig. 84.4. The endarterectomy is best ended by pulling the plaque transversely away from the artery with lateral traction. One should avoid pulling out or down on the plaque, which is more likely to result in a step-off that can be difficult to correct. Tacking sutures should be used only if necessary. Hypoglossal nerve (XII) External carotid artery Internal carotid artery Internal jugular vein Figure 84.2 Operative Field. Note the internal jugular vein mobilized posteri- orly after ligation of the anterior facial branch and the hypoglossal nerve crossing the vessels superior to the bifurcation. CHAPTER 84 Carotid Endarterectomy 1187 everting the adventitia and mobilizing it upward while gentle caudad traction is applied to the plaque. This maneuver is performed distally into the orifices of the ICA and ECA and then proximally into the CCA. Once the endarterectomy is complete, the divided bifurcation is reunited with a simple end-to-end anastomosis. Kieny and coworkers introduced a modification of eversion endarterectomy in 1985 in which the origin of the ICA is ex- cised obliquely off the carotid bifurcation, and is inverted on its own, and endarterectomy of the CCA and ECA is performed through an arteriotomy in the side of the carotid bifurcation. 60 The ICA is reanastomosed to the carotid bifurcation primarily (Fig. 84.6). Advantages of the eversion technique are that the anasto- mosis can be performed rapidly and it is not prone to resteno- sis, and therefore patching is not required. The disadvantages of this technique are that more extensive dissection is some- times necessary to mobilize the vessels during the eversion; the procedure does not lend itself readily to shunting (although shunting is not precluded by this technique), and it can be dif- ficult to visualize the endpoint in the ICA after the plaque has been removed. Therefore, in the author’s opinion, a comple- tion study should be performed. This technique is particularly effective for dealing with a redundant, coiled, or kinked ICA as the ICA can be pulled down and straightened and the re- dundant portion excised. The remaining portion of the ICA is spatulated and reattached to the arteriotomy on the carotid bifurcation. Comparison of Conventional and Eversion Carotid Endarterectomy In EVEREST (EVERsion CEA vs. Standard Trial study), a randomized, prospective multicenter study including more than 1400 patients randomized to eversion or standard CEA, there were no statistically significant differences in outcomes between the two techniques, although a slightly higher inci- dence of perioperative complications was noted with eversion CEA and a slightly higher incidence of restenosis with stan- dard CEA. While other studies have shown better outcomes with eversion CEA, 61 a large metaanalysis comparing eversion to conventional CEA found no significant differences in the rate of perioperative stroke or death (1.7% vs. 2.6%, odds ratio [OR] 0.44; 95% confidence interval [CI], 0.10–1.82), but did note that eversion endarterectomy was associated with a lower rate of restenosis during follow-up (2.5% vs. 5.2%, OR 0.48; 95% CI, 0.32–0.72). 62 EXPOSURE FOR HIGH LESIONS The carotid bifurcation can be located anywhere between the second and seventh cervical vertebrae, and a bifurcation located high in the neck poses technical challenges that can increase the perioperative risk for stroke and cranial nerve injury. Ideally, one will recognize a high bifurcation on the preoperative imag- ing study. This is a potential advantage of CTA, in which bony anatomy is always included in the images. A conscious effort must be made to locate the bony anatomy with DSA if unsub- tracted images are not provided with the study, but the anatomy can still be defined from subtracted images. Bony landmarks are never provided with carotid duplex imaging, but an astute vascular technologist will note a high bifurcation and should record it in the report. The more commonly utilized imaging modality is duplex ultrasound, which can be used to identify bi- furcation and to facilitate the position of skin incision for easier exposure. Nasotracheal Intubation The initial approach is to utilize nasotracheal intubation. With the patient’s mouth closed, the vertical ramus of the mandible is displaced anteriorly 1–2 cm relative to its position when the mouth is open with an oral endotracheal tube. The additional few millimeters of exposure afforded by this maneuver will of- ten be the difference in achieving a suitable endarterectomy endpoint in the distal ICA. A B C D Figure 84.6 Eversion Endarterectomy. ( A ) Internal carotid artery transected from the bifurcation. ( B ) Adventitia teased back off the internal carotid artery plaque. ( C ) Plaque endarterectomized from the common carotid and origin of the external carotid artery. ( D ) Reanastomosis of the internal carotid artery to the bifurcation. (Modified from Saratzis N, Saratzis A, Milaras S, et al. Eversion carotid endarterectomy illustrated: tips and tricks of the procedure. Surg Rounds . 2006;29(8):382–389.) CHAPTER 84 Carotid Endarterectomy 1189 A recent metaanalysis by AbuRahma et al. found that the mean perioperative stroke rate for CEA with routine shunting was 1.4% and for routine nonshunting was 2%. For selective shunting, the stroke rate varied depending upon the method used for intraoperative monitoring. It ranged from 1.1% for cervical block anesthesia, 1.6% for EEG and carotid stump pressure, to 4.8% using TCD. The authors concluded that both routine and selective shunting are acceptable and should be employed at the surgeon’s discretion. 80 Stump Pressure Measurement of carotid stump pressure was the first method used to predict intraoperative ischemia. 81–83 In patients with measured stump pressures lower than 50 mm Hg, Hays and colleagues noted a 50% neurologic event rate in those who were not shunted versus a 10% rate in those who were in a series of 297 patients. 81 Kelly and coworkers measured stump pressure with concurrent EEG monitoring in 289 patients 82 and performed shunting only in those with evidence of isch- emia by EEG criteria. They found that 6% of patients with stump pressure higher than 50 mm Hg had ischemia by EEG criteria. Stump pressure correlated well with EEG findings in patients with completed strokes but had a false-negative rate of 77% in patients with vertebral artery disease. In another report using EEG as a “gold standard,” Harada and associates found that a stump pressure lower than 50 mm Hg had a positive predictive value of only 36%. 83 In this series, 11% of patients with ischemia by EEG criteria would not have received shunts and 64% of patients with a stump pressure lower than 50 mm Hg would have received them unnecessarily by stump pressure criteria. Similarly, Brewster and coworkers found that 11 of 17 patients with ischemic EEG findings would not have been shunted by stump pressure criteria, and 7 of 63 would have unnecessary shunts. 84 Finocchi and colleagues used TCD to verify stump pressure and found that stump pressure did not correlate well with ischemia by TCD criteria in patients with postoperative deficits. 85 Clearly, even in the setting of what ap- pears to be a satisfactorily high stump pressure, there may still be regions of the brain that are relatively hypoperfused. Electroencephalographic and Somatosensory Evoked Potential Monitoring Intraoperative EEG monitoring is the most widely used meth- od of intraoperative cerebral monitoring. 86–92 Evidence sug- gests that electroencephalography is overly sensitive—positive in 10% to 40% of patients with unilateral carotid disease and positive in as many as 69% with bilateral carotid disease, there- by overestimating the number of people who require shunts. Blume and coworkers observed postoperative strokes in only 9% of patients with abnormal EEG findings in whom shunts were not placed. 92 Furthermore, several series have document- ed neurologic events that occurred in the absence of EEG ab- normality when shunting was not used. 86 Tempelhoff and as- sociates found that 5 of 6 patients with postoperative deficits in a series of 103 patients showed EEG changes only late in the operation, when shunting was no longer feasible. 93 Similarly, while there are multiple published studies on the use of SSEP suggesting that it is a useful adjunct to detect ischemia, 94,95 in a metaanalysis of 15 studies, Wober and col- leagues found that SSEP monitoring is not a reliable means of detecting ischemia and predicting neurologic outcome. 111 Transcranial Doppler TCD was introduced by Schneider and coworkers in 1988. 99 Visser and coauthors reported that with normal TCD findings one could safely avoid shunting in one-third of patients, but that abnormal findings on TCD predicted ischemia by EEG Figure 84.8 Mandibular Subluxation/Dislocation. ( A ) Normal bony anatomy with high carotid bifurcation. ( B ) The mandibular condyle is pulled forward onto the articular emi- nence, providing additional exposure when the subluxed man- dible is fixed in place at this position. ( C ) Illustrates the desired position of the temporomandibular ligaments during sublux- ation. ( D ) Illustrates the potential undesired position of the temporomandibular ligaments from dislocation, which may cause a tear in the capsular ligament. (Modified from Simoni- an GT, Pappas PJ, Padberg FT, et al. Mandibular subluxation for distal internal carotid exposure: technical considerations. J Vasc Surg . 1999;30:1116–1120. [ref. xvii].) A B Hypoglossal n. Mandibular condyle Articular eminence Infratemporal fossa Capsular ligament Lateral ligament C1 C2 Subluxation Normal C D Subluxation Dislocation 1188 SECTION 13 Cerebrovascular Diseases Division of the Digastric Muscle The next step to enhance distal exposure is to divide the poste- rior belly of the digastric muscle. The hypoglossal nerve should be carefully identified and protected before the muscle is divid- ed. Two other nerves that can be injured high in the neck are the spinal accessory nerve, which enters the tendinous portion of the sternocleidomastoid muscle usually in the upper third of the muscle, and the glossopharyngeal nerve, which lies deep to the digastric muscle. Resection of the Styloid Process The final maneuver that can be extremely effective in gaining cephalic exposure is resection of the styloid process (Fig. 84.7). After the posterior belly of the digastric muscle is divided, the insertions of the styloid apparatus: styloglossus, stylopharyn- geus, and stylohyoid muscles on the styloid process are excised with a scalpel. The stylohyoid muscle can be found posterosu- perior to the ECA and inserts into the posterior portion of the styloid process. In addition, the occipital artery runs along the inferior border of the posterior belly of the digastric muscle. Identification and division of the occipital artery can prevent bleeding secondary to trauma caused by retraction (Fig. 84.7). The styloid process is carefully resected with a rongeur. This can extend the exposure of the ICA by an additional 4 to 5 mm. However, damage to the underlying facial nerve is a potential complication of styloidectomy. 63–65 Anterior Subluxation of the Mandible Two other options can be used to improve exposure of a high bifurcation, and both require preoperative planning and co- ordination with an oral or plastic surgeon (Fig. 84.8). These patients should undergo nasotracheal intubation. Anterior subluxation of the mandible was described for use in high ca- rotid exposures in 1984. The authors describe their technique for subluxation as an evolution from full-mouth arch bars with circumdentate wiring to unilateral subluxation by cir- cummandibular/transnasal wiring. 66 For patients with healthy dentition, anterior subluxation of the mandible can be accom- plished by placing circumdental wires around the mandibular cuspid and bicuspid teeth on the side ipsilateral to the vascu- lar lesion. Corresponding wires should be placed around the corresponding contralateral maxillary teeth. The mandible is then subluxed anteriorly and the wires are twisted together to hold the fixation. Patients with poor dentition can have arch bars placed prior to wiring to facilitate the placement of the wires. 67 An even more aggressive approach involves the use of a complete vertical osteotomy through the vertical ramus of the mandible and separation of the mandible to expose the ICA. CEREBRAL PROTECTION AND MONITORING Shunting CEA may be performed with the routine nonuse of shunts, routine shunting, or selective shunting. 68–80 Under GA, selec- tive shunting may be determined by intraoperative measure- ment of carotid stump pressure, intraoperative monitoring of the EEG or somatosensory evoked potentials (SSEP), measure- ment of MCA flow by TCD, and monitoring with cerebral ox- imetry. 81–105 An alternative method is to perform CEA under RA, with shunt insertion if symptoms develop after the carotid artery is clamped. 106–110 These adjuncts are designed to detect intraoperative cerebral ischemia, whereas TCD has the added advantage of detecting intraoperative emboli. Placing a shunt has the capacity only to prevent ischemic stroke, but it could increase the risk for embolic stroke if performed poorly. Intraoperative cerebral ischemia is a rel- atively uncommon cause of intraoperative stroke. 73–76 This would support the argument of the routine nonshunters who believe that cerebral ischemia is a rare cause of stroke, and that shunting may do more harm than good (by causing em- bolic complications) so that even selective shunting is never justified. However, it is clear that cerebral ischemia can lead to perioperative stroke 73–76 and can be completely relieved by placement of a shunt. This should translate into the pre- vention of stroke in these patients if embolic complications related to shunt placement are minimized. In fact, there is evidence that the benefits of shunting outweigh the risks in these patients. 78,79 XI OA C1 SP M IJV SPM SHM SGM MV MA Figure 84.7 Anatomic Relationships of the Styloid Process. C1 , transverse pro- cess of C1; IJV , internal jugular vein; M , mandible; MA , maxillary artery; MV , maxillary vein; OA , occipital artery; SGM , styloglossus muscle; SHM , stylohyoid muscle; SP , styloid process; SPM , stylopharyngeus muscle; XI , spinal accessory nerve. (Modified from Izci Y, Moftakhar R, Pyle M, et al. Retromandibular fossa approach to the high cervical internal carotid artery: an anatomic study. Neurosur- gery . 2008;62(5 Suppl 2):ONS363–ONS369.)
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 1182 First performed in the 1950s, carotid endarterectomy (CEA) experienced remarkable growth in the 1970s and 1980s af- ter several studies demonstrated that carotid stenosis was an important risk factor for disabling stroke and death, 1–6 and a randomized multicenter trial published in 1969 showed that carotid surgery reduced the incidence of stroke from symp- tomatic carotid lesions. 7 However, subsequent experience documented high complication rates, thus compromising the 84 CHAPTER Carotid Endarterectomy BRUCE A. PERLER EPIDEMIOLOGY 1183 Incidence 1183 Etiology 1183 INDICATIONS FOR CAROTID ENDARTERECTOMY 1183 PREOPERATIVE IMAGING 1183 PERIOPERATIVE MEDICAL MANAGEMENT 1183 Beta- Blockers 1183 Antiplatelet Therapy 1183 Heparin 1184 Protamine Administration 1184 Dextran 1184 Statins 1184 OPERATIVE TECHNIQUE 1184 Anesthesia 1184 Patient Positioning 1184 Skin Incision 1184 Carotid Exposure 1185 Conventional Endarterectomy 1185 Eversion Endarterectomy 1186 Comparison of Conventional and Eversion Carotid Endarterectomy 1187 EXPOSURE FOR HIGH LESIONS 1187 Nasotracheal Intubation 1187 Division of the Digastric Muscle 1188 Resection of the Styloid Process 1188 Anterior Subluxation of the Mandible 1188 CEREBRAL PROTECTION AND MONITORING 1188 Shunting 1188 Stump Pressure 1189 Electroencephalographic and Somatosensory Evoked Potential Monitoring 1189 Transcranial Doppler 1189 Awake Carotid Endarterectomy with Regional or Local Anesthesia 1190 Routine Shunting 1190 ARTERIOTOMY CLOSURE 1190 Patch Material 1190 COMPLETION STUDIES 1191 Results of Completion Studies 1191 PERIOPERATIVE STROKE MANAGEMENT 1192 Intraoperative 1192 Postoperative 1192 SURGICAL RESULTS 1193 Randomized Trials 1193 Institutional Experience 1194 COMPLICATIONS 1194 Cardiac 1194 Cranial Nerve Injury 1194 Hemodynamic Instability 1197 Cerebral Hyperperfusion Syndrome 1197 Other Complications 1197 Recurrent Carotid Stenosis 1198 Reoperative Carotid Endarterectomy 1198 Carotid Artery Stenting Versus Repeat Carotid Endarterectomy 1198 SPECIAL CONSIDERATIONS 1198 Combined Carotid Artery and Cardiac Disease 1198 Advanced Age 1199 Gender 1199 Race 1200 Symptomatic Disease with Less Than 50% Carotid Stenosis: Intraplaque Hemorrhage 1200 Symptomatic Disease: Limb-Shaking Transient Ischemic Attacks 1201 External Carotid Endarterectomy 1201 Radiation-Induced Carotid Disease 1201 Hospital/Surgeon Volume 1202
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 CHAPTER 84 Carotid Endarterectomy 1183 potential benefit of CEA. 7,8 However, several randomized con- trolled trials (RCTs) performed in the 1990s definitively estab- lished the safety and efficacy of CEA and its superiority over the best medical management of patients with symptomatic and asymptomatic carotid disease. 9–12 EPIDEMIOLOGY Incidence Nearly 800,000 strokes occur annually in the United States: ap- proximately 15% are fatal, 15% to 20% are severely disabling, and another 15% to 20% of stroke patients who recover will experience a subsequent disabling stroke. As many as 87% of these strokes are ischemic, and atherosclerotic disease of the cervical carotid artery is responsible for approximately 20% of ischemic strokes. 13 Etiology Strokes secondary to carotid artery stenosis are a consequence of atheroembolization, thromboembolism, or are secondary to a low flow state through the carotid artery. INDICATIONS FOR CAROTID ENDARTERECTOMY Based on the most recent evidence-based guidelines published by the Society for Vascular Surgery, CEA is recommended for most symptomatic patients with a 50% to 99% internal ca- rotid artery (ICA) stenosis. Further, CEA should be considered for patients with a 70% to 99% asymptomatic ICA stenosis if the perioperative stroke and death rate is less than 3% and if the patient has at least a 3- to 5- year life expectancy. 14 In the symptomatic patient with a 50% to 99% ICA stenosis, and either medical or anatomic contraindications to CEA, carotid artery stenting (CAS) should be considered (see Chapter 85). Medical therapy, rather than CEA or CAS, should be selected in symptomatic patients with a less than 50% ICA stenosis, al- though there is some recent evidence suggesting that CEA may be indicated for rare symptomatic patients with <50% ICA stenoses (see below). Medical therapy rather than CAS is more appropriate for asymptomatic patients with a greater than 60% stenosis and medical or surgical contraindications. 14 PREOPERATIVE IMAGING Duplex ultrasound in an accredited laboratory is the most appropriate first test to evaluate the patient with suspected carotid artery disease, with either CTA or MRA reserved for patients with suspected disease proximal or distal to the neck, when there are indeterminate duplex findings, or other con- founding issues. 15–18 There is some evidence that CTA under- estimates, and MRA overestimates, the degree of stenosis. It is the practice in some centers to proceed to endarterectomy based on duplex findings alone. Since the benefit of CEA is highly dependent on the degree of stenosis, others maintain that verification of duplex findings is essential before proceed- ing to operation. 19 Clearly, if the patient is found to have an intermediate stenosis and is asymptomatic, one should per- form at least another noninvasive test to confirm this finding before recommending CEA. If there is discordance between these studies, one should either obtain a third noninvasive test or proceed to angiography. PERIOPERATIVE MEDICAL MANAGEMENT Risk stratification is important in determining the most appro- priate preoperative cardiac work-up and perioperative manage- ment of the patient undergoing CEA (see Chapter 32). The American Heart Association (AHA) perioperative guidelines classify CEA as an intermediate-risk procedure. 20,21 The peri- operative medical management of the patient undergoing CEA should include blood pressure control, statin, and antiplatelet therapy, and in selected cases beta blockade. Beta- Blockers Based upon early registry data, it was felt that all patients with vascular disease would benefit from perioperative beta block- ade. 19 This recommendation has evolved based on several large trials. 20–22 Perioperative beta blockade, with a goal of achieving a maximum heart rate of 60 to 80 beats per minute, is rec- ommended in the recent Society for Vascular Surgery carotid guidelines. 14 However, recent experience has moderated these clinical recommendations. 23 Specifically, beta-blockers should not be started in the preoperative period to improve short-term outcomes. Among patients with indications for beta blockade treatment long term, use may be individualized preoperatively. Patients on long-term beta-blockers should continue the use perioperatively. Antiplatelet Therapy Metaanalyses of antiplatelet therapy trials published by the UK Antithrombotic Trialist Group in 1994 and 2002 concluded that antiplatelet therapy significantly reduces the incidence of stroke in high-risk patients, with a resultant 25% reduction in strokes overall. 24 The majority of these studies included aspi- rin or aspirin plus another antiplatelet agent. Recent studies of clopidogrel provide evidence that perioperative embolization is decreased without an increase in bleeding complications or transfusion requirements after CEA. Other antiplatelet agents, such as ticlopidine and glycoprotein IIb/IIIa antagonists, have not been specifically studied during CEA and generally have a higher risk profile than ASA or clopidogrel. Based on this evi- dence, it is possible to recommend either ASA or clopidogrel, or both, for use before and after CEA. Based upon the prepon- derance of evidence, the author does not withhold aspirin and will continue clopidogrel if there is a clinical indication in the CEA patient. 14,25
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 1184 SECTION 13 Cerebrovascular Diseases Heparin Unfractionated heparin (UFH) is routinely used intraopera- tively to prevent carotid thrombosis despite a lack of level I evi- dence to support this practice. The combination of aspirin and intraoperative heparin administration appears to be especially effective in preventing thrombosis. 25,26 Protamine Administration Numerous publications have examined whether reversing hep- arin with protamine during CEA is safe. 27–29 The preponder- ance of recent evidence suggests that protamine administration does not increase perioperative stroke risk, although the au- thor prefers not to use it routinely unless there is truly unusual bleeding. 30 Dextran Dextran is a polysaccharide that inhibits platelet aggrega- tion. 31 It has been used to control embolic episodes both preoperatively and postoperatively. British investigators in 1997 showed that a 6-hour dextran infusion effectively controlled postoperative embolic events as measured by transcranial Doppler (TCD), with a 0% stroke and mortal- ity rate in a series of 100 patients. 32–35 The author favors a dextran infusion for 24 hours after CEA to control plate- let aggregation on the endarterectomy site and potential microembolization. Statins The potential benefits of statins in patients with carotid artery disease are several-fold. A reduction in cholesterol levels with statins may be associated with plaque regression, reduced carot- id artery intima–media thickness, and also a lower rate of com- bined cardiovascular events. 36–51 Numerous trials conducted over the past decade have specifically demonstrated statin med- ications to be highly effective in primary and secondary stroke prevention. 38–40 Furthermore, it appears that the stroke pre- vention benefits of statins are related to the pleiotropic effects of statin medications rather than their cholesterol-lowering effects. In addition, a recent metaanalysis demonstrated that statins are associated with a reduced rate of perioperative car- diac morbidity and overall mortality in patients undergoing noncardiac surgical procedures. 52 In a series of 1566 patients undergoing CEA at the author’s institution, statins were associated with a reduced 30-day in- cidence of stroke (1.2% vs. 4.5%, P = .002), TIA (1.5% vs. 3.6%, P = .01), and mortality (0.3% vs. 2.1%, P = .002). 53 A large administrative database analysis from Canada document- ed a significantly lower rate of perioperative stroke and death in symptomatic patients who were taking statin medications at the time of CEA. 54 Furthermore, LaMuraglia and cowork- ers reported that lipid-lowering agents were associated with significant protection against recurrent carotid stenosis after CEA. 55 The evidence seems clear that all patients undergoing CEA should be taking statin medications at the time of surgery, and long term. OPERATIVE TECHNIQUE Anesthesia CEA may be performed under general anesthesia (GA), re- gional anesthesia (RA) with deep or superficial cervical block, and even under pure local anesthesia (LA), with comparable lengths of stay. The majority of studies comparing the two techniques have reported improved perioperative cardiac sta- bility with RA, but this does not necessarily result in a reduced incidence of myocardial infarction (MI). 56,57 Disadvantages of RA include patient discomfort or anxiety, risk of seizure or allergic reaction, anxiety for the operating sur- geon, and compromise of technique in a teaching setting. The main benefit of LA is that it facilitates efficient selective shunt- ing if that is the surgeon’s preference (see below). Patient Positioning A roll is placed behind the scapulae used in conjunction with a padded ring under the head to achieve some extension of the neck without being overextended. If LA or RA is used, a Mayo stand is placed over the patient’s head to suspend the surgi- cal drapes away from the patient’s face to prevent sensations of claustrophobia. The patient is placed in the flexed position with the table rotated to expose the side of the neck to be oper- ated on. Skin Incision One of two skin incisions may be used (Fig. 84.1). The stan- dard incision is a longitudinal incision parallel to the medial border of the sternocleidomastoid muscle. The upper portion of the incision is angled posterior to the earlobe if cephalic exposure above the angle of the jaw is required. An alterna- tive method is to place the incision in an appropriately located Figure 84.1 Longitudinal and Transverse Skin Incisions for Carotid Endar- terectomy.
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 CHAPTER 84 Carotid Endarterectomy 1185 skin crease, usually 1 to 2 cm inferior to the angle of the jaw. If the incision is made too low, more cephalic exposure can be obtained by extending the skin crease incision posteriorly. If the incision is made too high, more caudal exposure can be obtained by extending the incision more anteriorly. Carotid Exposure Carotid exposure is described in Chapter 52. Manipulation of the carotid artery should be minimized because intraoperative embolization can result from careless handling. There are sev- eral key anatomic structures that merit emphasis. The external jugular vein lies deep to the platysma and is more commonly encountered with an oblique skin crease incision. The facial vein is identified crossing medially in the base of the wound and divided; sometimes it has an early bifurcation or trifur- cation, and multiple branches need to be ligated. The vagus nerve is identified in the carotid sheath, usually located pos- teriorly between the jugular vein and carotid artery, although in a minority of patients it may lie anteriorly. The common carotid artery (CCA) is controlled circumferentially with an umbilical tape and a Rummel tourniquet. The ansa cervicalis nerve should be identified; it usually lies medial to the distal CCA and identifying this nerve facilitates safe dissection of the carotid bifurcation and avoids injury to the hypoglossal nerve, which crosses medially from a superior to an inferior location (Fig. 84.2). The superior thyroid artery is controlled with a tie or plastic vessel loop and the external carotid artery (ECA) is controlled with a vessel loop. Finally, the ICA should be ex- posed and controlled with a vessel loop distal to the plaque, where the artery has a typical bluish appearance because of translucency of the vessel. During dissection of the carotid bi- furcation and its branches, one should avoid dissecting in the crotch of the carotid bifurcation to avoid injuring the carotid body to minimize hemodynamic instability and troublesome bleeding. If hemodynamic instability results, the carotid body can be gently injected with 1% lidocaine. Before clamping, the patient is administered 70 to 100 U/kg of heparin, which is allowed to circulate for 3 minutes. The ICA is clamped first to prevent the embolization that can result when the CCA or ECA is clamped. Care should be taken to make sure that the ICA is clamped on a normal portion of the artery distal to the plaque. If LA or intraoperative electroencephalography is used for selective shunting, a test clamp on the distal ICA should be applied for at least 3 minutes to check for changes in the neuro- logic examination or electroencephalographic (EEG) pattern. If such changes occur, the artery should be unclamped to allow reperfusion before reclamping and opening the carotid bifur- cation; opening the bifurcation and placing a shunt may take 2 to 3 minutes and should not be performed while the brain is already ischemic. However, unclamping the ICA introduces the potential for embolization from disrupted plaque. If carotid stump pressure is to be measured, clamps are placed on the CCA and the ECA, and a needle connected to a pressure line is placed into the distal CCA below the carotid bifurcation. Both clamping the CCA and placing the needle into the artery introduce the potential for embolization. Conventional Endarterectomy The conventional technique for CEA consists of a vertical arte- riotomy and closure usually by patch angioplasty. One should avoid making the incision too close to the flow divider at the ECA origin because this can distort the anatomy and make the closure more difficult (Fig. 84.3). The endarterectomy begins in the CCA in the plane be- tween the media and the adventitia. The proximal endpoint in the distal CCA is established and the plaque is trimmed in that location in a beveled manner. The endarterectomy is continued into the orifice of the ECA, first with a Freer elevator and then with a fine clamp that is passed up into the ECA in the plane of the endarterectomy and spread to further mobilize the plaque away from the adventitia in the 6-, 9- , and 12- o’clock posi- tions; it is usually difficult to pass the clamp in this plane at the 3- o’clock position next to the flow divider. The vessel loop on the ECA is released transiently while the plaque is everted from within the ECA. The endpoint of the plaque is inspected; an ideal endpoint is gradually tapering and feathered (Fig. 84.4). All loose bits of intima and media in the orifice of the ECA should be removed, although others believe that endarterec- tomy of the ECA may be neglected without compromising results. 58 A technically perfect endpoint in the ICA is critical. Occa- sionally, special maneuvers may be required to expose the distal ICA to extend the arteriotomy to achieve an acceptable end- point, as seen in Fig. 84.4. The endarterectomy is best ended by pulling the plaque transversely away from the artery with lateral traction. One should avoid pulling out or down on the plaque, which is more likely to result in a step-off that can be difficult to correct. Tacking sutures should be used only if necessary. Hypoglossal nerve (XII) External carotid artery Internal carotid artery Internal jugular vein Figure 84.2 Operative Field. Note the internal jugular vein mobilized posteri- orly after ligation of the anterior facial branch and the hypoglossal nerve crossing the vessels superior to the bifurcation.
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 1186 SECTION 13 Cerebrovascular Diseases Repairing the arteriotomy with a patch angioplasty repre- sents the standard of care in contemporary practice (Fig. 84.5). A variety of patch materials are available, including autologous vein, polytetrafluoroethylene (PTFE), woven polyester (Da- cron), and bovine pericardium, and no material appears to be clearly superior to another (see below). When the suture line is nearly completed, the CCA and ICA clamps are briefly sequentially released to flush air or debris (or both) out of the arteries. The carotid bifurcation is flushed vig- orously with heparinized saline and inspected again for debris or intimal flaps before the arteriotomy is finally closed. Once again, the clamp on the ICA is briefly released to fill the bifur- cation with blood. It is then replaced while the clamps on the CCA and ECA are released so that any remaining air or debris will be flushed up the territory of the ECA rather than the ICA. At this point the ICA clamp is removed. Any bleeding from the suture line is addressed at this time. One should avoid reclamp- ing unless absolutely necessary to control bleeding to avoid the risk for formation of thrombus or a fibrin-platelet aggregate on the patch or endarterectomized vessel. Eversion Endarterectomy DeBakey originally described eversion endarterectomy with partial transection of the anterior portion of the carotid bi- furcation. 2 Etheredge revised DeBakey’s technique with complete transection of the bifurcation, 59 which allowed the origins of both the ICA and ECA to be everted for a lon- ger distance. The endarterectomy is performed by mobiliz- ing the entire circumference of the carotid adventitia off the plaque (described as a “circumcision” by Etheredge) and then A B Figure 84.3 ( A ) Initial operative exposure with the Rumel tourniquet around the common carotid artery and the internal and external carotid arteries isolated with vessel loops. ( B ) The arteriotomy has been made and the shunt, with a silk suture attached, lies within the vessel. Figure 84.4 Carotid endarterectomy specimen. Note the smooth endpoints of the distal plaque from the external and internal (longer portion) arteries. Figure 84.5 Patch Closure of the Arteriotomy for Carotid Endarterecto- my. Dacron was used in this case. Note the ansa cervicalis coursing along the vessel, the vagus nerve posteriorly, and the hypoglossal nerve at the apex of the incision.
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 CHAPTER 84 Carotid Endarterectomy 1187 everting the adventitia and mobilizing it upward while gentle caudad traction is applied to the plaque. This maneuver is performed distally into the orifices of the ICA and ECA and then proximally into the CCA. Once the endarterectomy is complete, the divided bifurcation is reunited with a simple end-to-end anastomosis. Kieny and coworkers introduced a modification of eversion endarterectomy in 1985 in which the origin of the ICA is ex- cised obliquely off the carotid bifurcation, and is inverted on its own, and endarterectomy of the CCA and ECA is performed through an arteriotomy in the side of the carotid bifurcation. 60 The ICA is reanastomosed to the carotid bifurcation primarily (Fig. 84.6). Advantages of the eversion technique are that the anasto- mosis can be performed rapidly and it is not prone to resteno- sis, and therefore patching is not required. The disadvantages of this technique are that more extensive dissection is some- times necessary to mobilize the vessels during the eversion; the procedure does not lend itself readily to shunting (although shunting is not precluded by this technique), and it can be dif- ficult to visualize the endpoint in the ICA after the plaque has been removed. Therefore, in the author’s opinion, a comple- tion study should be performed. This technique is particularly effective for dealing with a redundant, coiled, or kinked ICA as the ICA can be pulled down and straightened and the re- dundant portion excised. The remaining portion of the ICA is spatulated and reattached to the arteriotomy on the carotid bifurcation. Comparison of Conventional and Eversion Carotid Endarterectomy In EVEREST (EVERsion CEA vs. Standard Trial study), a randomized, prospective multicenter study including more than 1400 patients randomized to eversion or standard CEA, there were no statistically significant differences in outcomes between the two techniques, although a slightly higher inci- dence of perioperative complications was noted with eversion CEA and a slightly higher incidence of restenosis with stan- dard CEA. While other studies have shown better outcomes with eversion CEA, 61 a large metaanalysis comparing eversion to conventional CEA found no significant differences in the rate of perioperative stroke or death (1.7% vs. 2.6%, odds ratio [OR] 0.44; 95% confidence interval [CI], 0.10–1.82), but did note that eversion endarterectomy was associated with a lower rate of restenosis during follow-up (2.5% vs. 5.2%, OR 0.48; 95% CI, 0.32–0.72). 62 EXPOSURE FOR HIGH LESIONS The carotid bifurcation can be located anywhere between the second and seventh cervical vertebrae, and a bifurcation located high in the neck poses technical challenges that can increase the perioperative risk for stroke and cranial nerve injury. Ideally, one will recognize a high bifurcation on the preoperative imag- ing study. This is a potential advantage of CTA, in which bony anatomy is always included in the images. A conscious effort must be made to locate the bony anatomy with DSA if unsub- tracted images are not provided with the study, but the anatomy can still be defined from subtracted images. Bony landmarks are never provided with carotid duplex imaging, but an astute vascular technologist will note a high bifurcation and should record it in the report. The more commonly utilized imaging modality is duplex ultrasound, which can be used to identify bi- furcation and to facilitate the position of skin incision for easier exposure. Nasotracheal Intubation The initial approach is to utilize nasotracheal intubation. With the patient’s mouth closed, the vertical ramus of the mandible is displaced anteriorly 1–2 cm relative to its position when the mouth is open with an oral endotracheal tube. The additional few millimeters of exposure afforded by this maneuver will of- ten be the difference in achieving a suitable endarterectomy endpoint in the distal ICA. A B C D Figure 84.6 Eversion Endarterectomy. ( A ) Internal carotid artery transected from the bifurcation. ( B ) Adventitia teased back off the internal carotid artery plaque. ( C ) Plaque endarterectomized from the common carotid and origin of the external carotid artery. ( D ) Reanastomosis of the internal carotid artery to the bifurcation. (Modified from Saratzis N, Saratzis A, Milaras S, et al. Eversion carotid endarterectomy illustrated: tips and tricks of the procedure. Surg Rounds . 2006;29(8):382–389.)
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 1188 SECTION 13 Cerebrovascular Diseases Division of the Digastric Muscle The next step to enhance distal exposure is to divide the poste- rior belly of the digastric muscle. The hypoglossal nerve should be carefully identified and protected before the muscle is divid- ed. Two other nerves that can be injured high in the neck are the spinal accessory nerve, which enters the tendinous portion of the sternocleidomastoid muscle usually in the upper third of the muscle, and the glossopharyngeal nerve, which lies deep to the digastric muscle. Resection of the Styloid Process The final maneuver that can be extremely effective in gaining cephalic exposure is resection of the styloid process (Fig. 84.7). After the posterior belly of the digastric muscle is divided, the insertions of the styloid apparatus: styloglossus, stylopharyn- geus, and stylohyoid muscles on the styloid process are excised with a scalpel. The stylohyoid muscle can be found posterosu- perior to the ECA and inserts into the posterior portion of the styloid process. In addition, the occipital artery runs along the inferior border of the posterior belly of the digastric muscle. Identification and division of the occipital artery can prevent bleeding secondary to trauma caused by retraction (Fig. 84.7). The styloid process is carefully resected with a rongeur. This can extend the exposure of the ICA by an additional 4 to 5 mm. However, damage to the underlying facial nerve is a potential complication of styloidectomy. 63–65 Anterior Subluxation of the Mandible Two other options can be used to improve exposure of a high bifurcation, and both require preoperative planning and co- ordination with an oral or plastic surgeon (Fig. 84.8). These patients should undergo nasotracheal intubation. Anterior subluxation of the mandible was described for use in high ca- rotid exposures in 1984. The authors describe their technique for subluxation as an evolution from full-mouth arch bars with circumdentate wiring to unilateral subluxation by cir- cummandibular/transnasal wiring. 66 For patients with healthy dentition, anterior subluxation of the mandible can be accom- plished by placing circumdental wires around the mandibular cuspid and bicuspid teeth on the side ipsilateral to the vascu- lar lesion. Corresponding wires should be placed around the corresponding contralateral maxillary teeth. The mandible is then subluxed anteriorly and the wires are twisted together to hold the fixation. Patients with poor dentition can have arch bars placed prior to wiring to facilitate the placement of the wires. 67 An even more aggressive approach involves the use of a complete vertical osteotomy through the vertical ramus of the mandible and separation of the mandible to expose the ICA. CEREBRAL PROTECTION AND MONITORING Shunting CEA may be performed with the routine nonuse of shunts, routine shunting, or selective shunting. 68–80 Under GA, selec- tive shunting may be determined by intraoperative measure- ment of carotid stump pressure, intraoperative monitoring of the EEG or somatosensory evoked potentials (SSEP), measure- ment of MCA flow by TCD, and monitoring with cerebral ox- imetry. 81–105 An alternative method is to perform CEA under RA, with shunt insertion if symptoms develop after the carotid artery is clamped. 106–110 These adjuncts are designed to detect intraoperative cerebral ischemia, whereas TCD has the added advantage of detecting intraoperative emboli. Placing a shunt has the capacity only to prevent ischemic stroke, but it could increase the risk for embolic stroke if performed poorly. Intraoperative cerebral ischemia is a rel- atively uncommon cause of intraoperative stroke. 73–76 This would support the argument of the routine nonshunters who believe that cerebral ischemia is a rare cause of stroke, and that shunting may do more harm than good (by causing em- bolic complications) so that even selective shunting is never justified. However, it is clear that cerebral ischemia can lead to perioperative stroke 73–76 and can be completely relieved by placement of a shunt. This should translate into the pre- vention of stroke in these patients if embolic complications related to shunt placement are minimized. In fact, there is evidence that the benefits of shunting outweigh the risks in these patients. 78,79 XI OA C1 SP M IJV SPM SHM SGM MV MA Figure 84.7 Anatomic Relationships of the Styloid Process. C1 , transverse pro- cess of C1; IJV , internal jugular vein; M , mandible; MA , maxillary artery; MV , maxillary vein; OA , occipital artery; SGM , styloglossus muscle; SHM , stylohyoid muscle; SP , styloid process; SPM , stylopharyngeus muscle; XI , spinal accessory nerve. (Modified from Izci Y, Moftakhar R, Pyle M, et al. Retromandibular fossa approach to the high cervical internal carotid artery: an anatomic study. Neurosur- gery . 2008;62(5 Suppl 2):ONS363–ONS369.)
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 CHAPTER 84 Carotid Endarterectomy 1189 A recent metaanalysis by AbuRahma et al. found that the mean perioperative stroke rate for CEA with routine shunting was 1.4% and for routine nonshunting was 2%. For selective shunting, the stroke rate varied depending upon the method used for intraoperative monitoring. It ranged from 1.1% for cervical block anesthesia, 1.6% for EEG and carotid stump pressure, to 4.8% using TCD. The authors concluded that both routine and selective shunting are acceptable and should be employed at the surgeon’s discretion. 80 Stump Pressure Measurement of carotid stump pressure was the first method used to predict intraoperative ischemia. 81–83 In patients with measured stump pressures lower than 50 mm Hg, Hays and colleagues noted a 50% neurologic event rate in those who were not shunted versus a 10% rate in those who were in a series of 297 patients. 81 Kelly and coworkers measured stump pressure with concurrent EEG monitoring in 289 patients 82 and performed shunting only in those with evidence of isch- emia by EEG criteria. They found that 6% of patients with stump pressure higher than 50 mm Hg had ischemia by EEG criteria. Stump pressure correlated well with EEG findings in patients with completed strokes but had a false-negative rate of 77% in patients with vertebral artery disease. In another report using EEG as a “gold standard,” Harada and associates found that a stump pressure lower than 50 mm Hg had a positive predictive value of only 36%. 83 In this series, 11% of patients with ischemia by EEG criteria would not have received shunts and 64% of patients with a stump pressure lower than 50 mm Hg would have received them unnecessarily by stump pressure criteria. Similarly, Brewster and coworkers found that 11 of 17 patients with ischemic EEG findings would not have been shunted by stump pressure criteria, and 7 of 63 would have unnecessary shunts. 84 Finocchi and colleagues used TCD to verify stump pressure and found that stump pressure did not correlate well with ischemia by TCD criteria in patients with postoperative deficits. 85 Clearly, even in the setting of what ap- pears to be a satisfactorily high stump pressure, there may still be regions of the brain that are relatively hypoperfused. Electroencephalographic and Somatosensory Evoked Potential Monitoring Intraoperative EEG monitoring is the most widely used meth- od of intraoperative cerebral monitoring. 86–92 Evidence sug- gests that electroencephalography is overly sensitive—positive in 10% to 40% of patients with unilateral carotid disease and positive in as many as 69% with bilateral carotid disease, there- by overestimating the number of people who require shunts. Blume and coworkers observed postoperative strokes in only 9% of patients with abnormal EEG findings in whom shunts were not placed. 92 Furthermore, several series have document- ed neurologic events that occurred in the absence of EEG ab- normality when shunting was not used. 86 Tempelhoff and as- sociates found that 5 of 6 patients with postoperative deficits in a series of 103 patients showed EEG changes only late in the operation, when shunting was no longer feasible. 93 Similarly, while there are multiple published studies on the use of SSEP suggesting that it is a useful adjunct to detect ischemia, 94,95 in a metaanalysis of 15 studies, Wober and col- leagues found that SSEP monitoring is not a reliable means of detecting ischemia and predicting neurologic outcome. 111 Transcranial Doppler TCD was introduced by Schneider and coworkers in 1988. 99 Visser and coauthors reported that with normal TCD findings one could safely avoid shunting in one-third of patients, but that abnormal findings on TCD predicted ischemia by EEG Figure 84.8 Mandibular Subluxation/Dislocation. ( A ) Normal bony anatomy with high carotid bifurcation. ( B ) The mandibular condyle is pulled forward onto the articular emi- nence, providing additional exposure when the subluxed man- dible is fixed in place at this position. ( C ) Illustrates the desired position of the temporomandibular ligaments during sublux- ation. ( D ) Illustrates the potential undesired position of the temporomandibular ligaments from dislocation, which may cause a tear in the capsular ligament. (Modified from Simoni- an GT, Pappas PJ, Padberg FT, et al. Mandibular subluxation for distal internal carotid exposure: technical considerations. J Vasc Surg . 1999;30:1116–1120. [ref. xvii].) A B Hypoglossal n. Mandibular condyle Articular eminence Infratemporal fossa Capsular ligament Lateral ligament C1 C2 Subluxation Normal C D Subluxation Dislocation
Order your copy of Rutherford’s Vascular Surgery and Endovascular Therapy, 2 Volume Set, 11th Edition at elsevierhealth.com/9780443286179 1190 SECTION 13 Cerebrovascular Diseases criteria only 60% of the time. 98 TCD has the unique advantage of detecting microemboli intraoperatively, which may alert the surgeon to avoid further vessel manipulation and microembo- lization. 100,101 However, Belardi and associates also reported that TCD (as well as stump pressure) was not accurate in pre- dicting cerebral ischemia. 102 Awake Carotid Endarterectomy with Regional or Local Anesthesia In view of these findings, performing CEA under RA is the most reliable method of predicting the need for selective shunt- ing. Shunt rates of 5% to 15% are consistently lower than with other modalities. 103,104,112 In two recent prospective trials in which both stump pressure and EEG measurements were re- corded before performing endarterectomy under RA, but in which the need to shunt was ultimately determined by neu- rologic changes, both EEG findings and stump pressure were found to inaccurately predict the need for shunting. 103,104 In a study by Calligaro and Dougherty, a cost analysis found that RA saved more than $3000 per case by avoiding EEG measure- ments. 113 Three studies have demonstrated a decreased length of stay with RA, 114–116 but in two of them the length of stay in the GA group was not reflective of modern practice, approximate- ly 5 days. 114,116,117 There is no evidence in the literature that demonstrates the cost effectiveness of selective shunting versus routine shunting, and insufficient data to conclude that CEA performed under RA is associated with a lower rate of MI or neurologic complications. 114–116 Routine Shunting One risk of selective shunting is that neurologic events may be attributable to the shunt itself secondary to embolism or isch- emia and may not occur with routine shunting. Specifically, se- lective shunting, regardless of the adjunct used, always involves a test clamp. In the case of stump pressure measurement, instru- menting the carotid artery with a needle introduces the added risk of embolism. When a test clamp is positive, there are two options. One is to unclamp the vessels and reperfuse the brain while preparations are made to shunt. This maneuver exposes the patient to the risk of embolization. The other option is to proceed with the endarterectomy and placement of a shunt. In this instance, the brain is ischemic when the test clamp be- comes positive and is exposed to an additional period of isch- emia while the shunt is being placed, whereas during routine shunting, shunt placement can usually be accomplished in 1 to 2 minutes after clamping before the brain becomes ischemic. The routine use of carotid shunts allows CEA to be per- formed in a consistent manner, which eliminates surgeon and patient anxiety, without the added cost or complexity of monitoring equipment. Studies consistently show that carotid shunting relieves the intracerebral ischemia caused by clamp- ing, whether measured by neurologic status, EEG changes, MCA flow on TCD, or cerebral blood flow, and there is no convincing evidence that placement of a shunt necessarily increases embolic complications or causes arterial injury lead- ing to more subacute or chronic complications. However, there is evidence that placing a shunt in the setting of severe isch- emia decreases the stroke rate 117 and may limit ischemia–re- perfusion injury. Further, Pärsson and associates have shown that carotid shunting diminishes the inflammatory response of ischemic brain injury, as demonstrated by the production of various inflammatory mediators. 118 This may be an important mechanism in the occurrence of delayed postoperative strokes, which can account for up to 70% of perioperative strokes. 76 Several large series including nearly 7000 patients have doc- umented a perioperative stroke rate of 1.0% to 1.6% with rou- tine shunting. 71,78–80 In the author’s practice, routine shunt- ing is the preferred technique. Despite acceptable results in some individuals’ hands, routine nonuse of shunts cannot be advocated in view of the abounding evidence that intraopera- tive ischemia can be a source of stroke that is preventable with shunts. Selective shunting based on stump pressure, TCD, or neurophysiologic monitoring does not accomplish the goal of improving results through decreased shunt use and only adds to the cost and complexity of the procedure. The only form of selective shunting that is truly reliable is that based on neuro- logic examination during RA. ARTERIOTOMY CLOSURE Considerable experience indicates that patch closure yields su- perior clinical and anatomic outcomes compared to primary arteriotomy closure. Patch Material Saphenous Vein Patches Saphenous vein patching has been used extensively with good results. Complications specific to saphenous vein patching include wound complications at the harvest site, potential compromise of a valuable conduit for later bypass procedures, and the potentially devastating complication of patch rupture, which has been reported to occur in 0.5% to 4% of cases. 119–123 Because most of these were ankle veins, several investigators recommended harvesting the greater saphenous vein (GSV) from above the knee. Lord and coworkers also noted that an- eurysmal expansion of saphenous vein patches can occur in up to 17% of patients. 124 Archie and Green investigated the relationship of GSV diam- eter and rupture pressure and found that GSVs with diameters less than 3.5 mm were more prone to rupture. 122 Their group also noted that women were three times more likely to have a GSV measuring less than 3.5 mm. Applying this knowledge to their practice, Archie found that by using a GSV with a distended vein diameter of greater than 3.5 mm and maintaining a carotid bulb diameter of less than 13 mm, patch rupture was completely avoided in a series of 534 patients over an 8-year period. 123 Synthetic Patches Synthetic materials that are commonly used include PTFE, Dacron, and bovine pericardium.