Carotid Endarterectomy: A Concise Review for the Surgical PA

Transcription

1 Carotid Endarterectomy: A Concise Review for the Surgical PA Every year, more than 795,000 Americans experience a stroke, 87% of which are ischemic strokes caused by a blockage of blood flow to the brain. 1 Carotid artery stenosis is a significant cause of this blockage of blood flow to the brain, directly increasing the risk of transient ischemic attacks and ischemic stroke. Carotid endarterectomy (CEA) is one of the surgical procedures most commonly performed for carotid artery stenosis in addition to carotid artery stenting (CAS). In this article, we will cover a concise review of the perioperative management in CEA. The Basics The carotid artery lumen most commonly becomes occluded by atherosclerosis, often at the carotid bifurcation into the internal and external carotid arteries. Risk factors for developing carotid stenosis include older age, male sex, diabetes, hypertension, smoking, and dyslipidemia. There are other nonatherosclerotic and anatomical causes of carotid stenosis such as radiation arteritis, dissection, and fibromuscular dysplasia. Carotid stenosis severity can be divided according to the reduction in carotid artery luminal diameter: - mild (<50%) - moderate (50%-69%) - severe (70-99%) Presentation & Diagnosis Carotid artery stenosis may be asymptomatic or symptomatic and associated with focal neurologic symptoms or contralateral deficits. Focal neurologic deficits correlate with signs and symptoms of an ischemic stroke or transient ischemic attack (TIA) such as sudden visual loss, weakness, or aphasia. Asymptomatic disease may be caught incidentally through imaging or discovery of a carotid bruit on physical exam. It should be noted that a carotid bruit does not necessarily correlate with the severity of the stenosis, but remains a useful aid in diagnosis. Duplex ultrasonography can be performed in both asymptomatic and symptomatic patients. It is not currently recommended to screen an asymptomatic adult, because there is no evidence that screening asymptomatic carotid stenosis reduces fatal or nonfatal strokes. 2 However, joint guidelines from multiple U.S. societies such as the American College of Cardiology, the American Heart association, the American Stroke Association, and the Society for Vascular Surgery suggest that it is reasonable to perform duplex ultrasonography to detect hemodynamically significant carotid stenosis in asymptomatic patients with carotid bruit. 3 Duplex ultrasonography can visualize plaque in the carotid arteries and provide an estimate of blood flow velocities that translate to the significance of stenosis. Magnetic resonance angiography (MRA) and computed tomography angiography (CTA) of the head and neck may also be used in diagnosis. These imaging techniques estimate spe-

2 cific percent stenosis in the carotid artery and may provide further detail of atherosclerotic plaque in the arterial wall. They may be used in patients when additional information is needed or when results from ultrasonography is inconclusive or ambiguous. Differences in ultrasonography and cerebral angiography may be less reliable with significant disease. 5 Preoperative Management Prior to surgery, a thorough neurological assessment should be performed to establish the patient s baseline neurological status. Because many patients with carotid artery stenosis have coexisting coronary atherosclerosis, consultation with a cardiologist is also valuable for recommendations on use of statins, beta blockers, and dual antiplatelet therapy. The American Heart Association and American Stroke Association recommend starting aspirin ( mg daily) in patients before CEA and continuing it indefinitely postoperatively. 4 CEA vs. Stenting As mentioned above, carotid endarterectomy (CEA) is one of the procedures most commonly performed for carotid artery stenosis in addition to carotid artery stenting (CAS). CEA removes atherosclerotic plaque, restoring cerebral blood flow and reducing the risk of stroke. A study called CREST, the Carotid Revascularization Endarterectomy versus Stenting Trial, was conducted on both symptomatic and asymptomatic carotid stenosis and showed no difference between the stenting group and the CEA group. The trial specifically looked at the end point of any stroke, myocardial infarction, or death during the periprocedural period (30 days) and ipsilateral stroke 10 years in patients who had no periprocedural event. Of note, all patients received dual antiplatelet therapy or aspirin therapy before and after the procedures. Both procedures were associated with rates of stroke that were less than 7% over a 10-year period. 13 CEA The North American Symptomatic Carotid Endarterectomy Trial (NASCET) demonstrated that the benefit of CEA is very significant in severe symptomatic carotid stenosis (>70%) and modest benefit in high-moderate stenosis (50-69%). 5 In asymptomatic patients it may be reasonable to perform CEA if there is more than 70% stenosis of the internal carotid artery if the risk of perioperative stroke, MI, and death is low. 4 Current research suggests that it is most beneficial and reasonable to perform CEA within 2 weeks following a TIA or stroke in the absence of contraindications. 4 Contraindications to CEA include the following: 7 absolute = asymptomatic complete carotid occlusion prior neck irradiation concurrent traceostomy prior radical neck dissection contralateral vocal cord paralysis from prior endarterectomy

3 atypical lesions location unacceptably high medical risk In patients with bilateral carotid stenosis, CEA should be performed separately on each side and separated by at least a week or more. 19 Surgical Procedure Anesthesia CEA procedures are typically less than 90 minutes and may be performed under both general and local anesthesia. 5 Under local anesthesia, neurologic function can be monitored with the awake patient by asking them to perform tasks with the contralateral hand while the surgeon is operating. Local anesthesia may be used with or without a superficial or deep cervical plexus block. Short-acting anesthetic agents are used for general anesthesia, and airway management through endotracheal intubation. Regardless of modality, monitoring of cerebral perfusion is a critical part of the procedure. Detection of cerebral ischemia after carotid clamping allows for quick response and treatment of suggested hypoperfusion or emboli. Multiple modalities exist, such as electroencephalography (EEG), cerebral perfusion monitoring, carotid stump pressure, transcranial doppler, and cerebral oximetry. As part of the intraoperative monitoring, arterial blood pressure is also carefully controlled, requiring preoperative placement of an arterial line. Intraoperatively, detection of pressure changes requires careful hemodynamic management and use of vasoactive drugs. Surgical Procedure Positioning Positioning of the patient for ideal exposure includes use of a roll across the shoulder blades to help hyperextend the neck. The patient should be in a semi-seated position and the neck gently rotated towards the contralateral side. Exposure Surgical preparation and drapes should allow exposure of important landmarks including the ear lobe, angle of the mandible, mastoid process, sternal notch, and clavicle. 15 Surgical Anatomy Most surgeons perform an oblique incision bordering the sternocleidomastoid muscle (SCM) and centered over the carotid bifurcation. An incision that extends too anterior may injure the marginal mandibular branch of the facial nerve. 19 For proper exposure, the platysma muscle is divided to expose the carotid sheath. Anatomical variations exist, but typically the aortic arch gives rise to the left common carotid artery (CCA) while the right CCA arises from the innominate artery, which is the first branch of the aorta. Each common carotid artery bifurcates into the internal carotid artery (ICA) and the external carotid artery (ECA).

4 The carotid artery is encased in the carotid sheath, which is an area surrounded by layers of fascia and housing other important structures including the vagus nerve and the internal jugular vein. Procedure Dissection for proximal and distal control of the artery is performed, typically from a point distal to the bifurcation of the ICA and ECA to a point beyond the ICA plaque. It is important to keep in mind that dissection of the carotid artery at the bifurcation may cause stimulation of the carotid body and result in reactive bradycardia. 10 In addition, the hypoglossal nerve may lie in close proximity to the carotid bifurcation. Once circumferentially dissected, the arteries can be isolated with vessel loops and clamped with vascular clamps. Prior to clamping, heparin may be administered. The order of clamping the arteries is important and performed in this order: first the ICA, then the CCA, and finally the ECA. A temporary carotid shunt may be used to provide cerebral blood flow during the procedure. For removal of the plaque, a longitudinal arteriotomy is performed on the ICA and a plane is carefully dissected between the plaque and the intima of the vessel. The plaque must be fully excised and the remaining intima of the vessel cleaned with heparinized saline to remove loose debris. A patch made of Dacron or bovine pericardium is the preferred method to repair the arteriotomy. It is sewn close to the arteriotomy and sized to fit its length and shape. With closure of the arteriotomy, the ICA is first allowed to back-bleed. Blood flow is then restored with the ECA before the CCA, and then finally antegrade flow is restored into the ICA. After hemostasis is achieved and protamine given to reverse the anticoagulation of heparin, the wound is closed in layers. The SCM, cervical fascia, and platysma are approximated, followed by closure of the skin. A small drain may be placed but is not required. Post-Operative Management The patient s neurologic status is immediately assess post-operatively for any focal deficits. The complications of CEA are related to the patient s underlying medical condition as well as techniques in performing the surgical procedure. 8 Post-operative complications include stroke, myocardial infarction, hyper perfusion syndrome, cervical hematoma, nerve injury, infection, and restenosis. Most importantly, perioperative medication management should be carefully implemented to reduce the risk of complications. A summary of common complications and interventions are listed in the table provided. 6,8

5 Post-operative Complication Cause Intervention Hypertension Hypotension disruption of cerebral autoregulation reisdual carotid hypersensitivity after plaque excision maintain systolic blood pressure between mmhg with medications such as labetalol (bolus or IV infusion) maintain systolic blood pressure between mmhg with medications such as phenylephrine Surgical Site Hematoma postoperative bleeding - proper reversal of anticoagulation - monitor airway and manage hypertension Pain manipulation of neck structures manage pain - opioids (may exacerbate respiratory depression) - acetaminophen Cranial Nerve damage (Manifestations) - Hypoglossal (tongue deviation ipsilateral to the CEA) - Facial (assymetric smile ipsilateral to CEA) - Recurrent laryngeal nerve (vocal cord paralysis, newonset hoarseness) - Sympathetic nerves (Horner s syndrome) - nerve compression from edema - prolonged or improper retraction - stretching or inadvertent clamping of nerves majority resolve after surgery* *cranial nerve injury occurs in about 5% of patients while permanent nerve injury in < 1% Infection surgical site or patch infection - use appropriate antibiotic prophylaxis - may require wound drainage and subsequent antibiotic therapy Restenosis early or late restenosis of the carotid artery due to cellular hyperplasia or progressive atherosclerotic disease - initiation of long-term prophylaxis with anti-platelet therapy - management of risk factors such as hypertension and smoking Patients may be discharged following observation and monitoring, to ensure adequate blood pressure management. Discharge typically occurs within 24 hours after surgery. 10 Appropriate long-term prophylaxis against ischemic cardiovascular events is initiated as mentioned previously, with aspirin or dual anti-platelet therapy. Follow-up with noninva-

6 sive imaging is reasonable to perform at 1 month, 6 months, and then annually after carotid endarterectomy to ensure patency of the repaired artery. 18 Conclusion CEA is a common surgical intervention for carotid stenosis that reduces the risk of stroke in appropriate surgical candidates. 5 Every patient should be carefully assessed when considering CEA and managed appropriately for the best surgical outcomes. The surgical PA can be well-informed and educated on this procedure by understanding the perioperative management of these patients. References 1. Benjamin E, Blaha M, Muntner P, et al. Heart Disease and Stroke Statistics-2017 Update: A Report From the American Heart Association. Circulation. March 7, 2017;135(10):e146-e Disease Screening. In: Esherick JS, Slater ED, David JA. eds. CURRENT Practice Guidelines in Primary Care 2017 New York, NY: McGraw-Hill. 3. Jonas DE, Feltner C, Amick HR, et al. Screening for Asymptomatic Carotid Artery Stenosis: A Systematic Review and Meta-Analysis for the U.S. Preventive Services Task Force. Rockville (MD): Agency for Healthcare Research and Quality (US); 2014 Jul. (Evidence Syntheses, No. 111.) Appendix A, Summary of Recommendations From Other Groups. 4. Brott T, Halperin J, Taylor A, et al ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/ CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS Guideline on the Management of Patients With Extracranial Carotid and Vertebral Artery Disease: Executive summary. Catheterization And Cardiovascular Interventions. n.d.;81(1):e75-e Ferguson G, Eliasziw M, Barnett H, et al. The North American Symptomatic Carotid Endarterectomy Trial - Surgical results in 1415 patients. Stroke. n.d.;30(9): Augoustides J, Gutsche JT. Anesthesia for carotid endarterectomy and carotid stenting. In: UpToDate, Nussmeier NA (Ed), UpToDate, Waltham, MA. 7. Fairman, R. Carotid endarterectomy. In: UpToDate, Collins KA (Ed), UpToDate, Waltham, MA. 8. Fairman, R. Complications of carotid endarterectomy. In: UpToDate, Collins KA (Ed), UpToDate, Waltham, MA. 9. Biller J, Thies W. When to operate in carotid artery disease. Am Fam Physician. January 15, 2000;61(2): Available from: MEDLINE Complete, Ipswich, MA. 10.Lin PH, Poi M, Matos J, Kougias P, Bechara C, Chen C. Lin P.H., Poi M, Matos J, Kougias P, Bechara C, Chen C Lin, Peter H., et al. Arterial Disease. In: Brunicardi F, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE. Brunicardi F, Andersen D.K., Billiar T.R., Dunn D.L., Hunter J.G., Matthews J.B., Pollock R.E. Eds. F. Charles Brunicardi, et al.eds. Schwartz's Principles of Surgery, 10e New York, NY: McGraw-Hill; 2015.

7 11. Rapp JH, Gasper W. Rapp J.H., Gasper W Rapp, Joseph H., and Warren Gasper.Arteries. In: Doherty GM. Doherty G.M. Ed. Gerard M. Doherty.eds. CUR- RENT Diagnosis & Treatment: Surgery, 14e New York, NY: McGraw-Hill; Owens CD, Gasper WJ, Johnson MD. Owens C.D., Gasper W.J., Johnson M.D. Owens, Christopher D., et al.blood Vessel & Lymphatic Disorders. In: Papadakis MA, McPhee SJ, Rabow MW. Papadakis M.A., McPhee S.J., Rabow M.W. Eds. Maxine A. Papadakis, et al.eds. Current Medical Diagnosis & Treatment 2017 New York, NY: McGraw-Hill. 13.Sardar P, Chatterjee S, Giri J, et al. Carotid Artery Stenting Versus Endarterectomy for Stroke Prevention: A Meta-Analysis of Clinical Trials. J Am Coll Cardiol. May 9, 2017;69(18): Brott T, Howard G, Lal B, et al. Long-Term Results of Stenting versus Endarterectomy for Carotid-Artery Stenosis. N Engl J Med. March 17, 2016;374(11): Longo C, Berguer R. Chapter 35. Carotid Endarterectomy. In: Minter RM, Doherty GM. eds. Current Procedures: Surgery New York, NY: McGraw-Hill; Fokkema M, de Borst GJ, Nolan BW, et al. Clinical relevance of cranial nerve injury following carotid endarterectomy. Eur J Vasc Endovasc Surg 2014; 47: Cunningham EJ, Bond R, Mayberg MR, et al. Risk of persistent cranial nerve injury after carotid endarterectomy. J Neurosurg 2004; 101: Carotid artery stenosis repair. In Dynamed Plus [database online]. EBSCO Information Services. dmp~an~t116305#periprocedural-management. Updated June 14, Accessed August 24, Carotid endarterectomy. In: Ellison E, Zollinger RM, Jr.. eds. Zollinger's Atlas of Surgical Operations, 10e New York, NY: McGraw-Hill.