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Carotid Endarterectomy (Cadaver)

Meghan Robinson1; Samuel Schwartz, MD2; Laura Boitano, MD2

1Lake Erie College of Osteopathic Medicine
2Massachusetts General Hospital

Abstract

Carotid artery stenosis is one of the leading causes of ischemic stroke worldwide. In the United States, nearly 800,000 strokes are reported each year, with ischemia accounting for 87% of them, and 15% traced to a carotid origin. An aging population and growing lifestyle factors have increased the lifetime risk of stroke over time. Carotid endarterectomy represents an effective surgical treatment for carotid artery stenosis in preventing the risk of future ischemic stroke. In this video-article, we demonstrate the surgical technique for carotid endarterectomy on a cadaver and discuss a typical case presentation of someone who may benefit from it. 

Case Overview

Background

Carotid artery stenosis occurs when atherosclerotic plaque builds up in the carotid artery, with risk factors similar to other atherosclerotic diseases including hypertension, hyperlipidemia, smoking, obesity, and diabetes.1-4 Carotid artery stenosis may be discovered following a transient ischemic attack (TIA), ischemic stroke, or incidentally on other imaging. Plaque is usually found in the common and internal carotid arteries within 2 cm of the carotid bulb due to complex flow patterns at that location.5 Carotid endarterectomy (CEA) refers to the surgical removal of atherosclerotic plaque from the carotid, one of the best-studied interventions for the prevention of future ischemic events in symptomatic patients with significant plaque burden. 

Focused History of the Patient

The video demonstrates the surgical procedure on a cadaver, but in this text, we will present and discuss the medical and surgical management of a typical patient who might benefit from CEA. The typical patient to be discussed is a 64-year-old male with a past medical history of myocardial infarction status post stenting of the LAD, hypertension, hyperlipidemia, and type 2 diabetes mellitus. He presented to the emergency department with a half-hour history of painless loss of vision in the left eye. He described it as beginning at the top of his visual field and gradually involving the entire field. His vision loss resolved in the emergency department without treatment. He reported two episodes in the past week of muscle weakness in his right leg, each lasting under an hour. Imaging in the emergency department revealed a 90% stenosis of the left carotid artery and a 55% stenosis of the right. He was medically optimized and referred to vascular surgery for evaluation.

The typical patient is older, has multiple cardiovascular risk factors, and presents with focal neurologic deficits that resolve completely within 24 hours, indicative of a TIA. The episodic painless loss of vision seen in this patient is referred to as a retinal TIA, also known as amaurosis fugax. One-sided muscle weakness can be described as a hemispheric TIA. During their workup, they are found to have stenosis of the carotid artery, necessitating referral to vascular surgery. 

Physical Exam

A physical exam revealed an overweight man with no focal neurologic deficits. The pupils were equal, round, and reactive to light; acuity was intact. Visual fields were full to confrontation, and ocular movements were intact. A bruit was auscultated bilaterally over the carotid bifurcation, easier to appreciate on the left. Lower extremity pulses were diminished bilaterally.

Physical exam in a patient with carotid artery stenosis may be unremarkable. A bruit may be auscultated over the internal carotid artery; however, this is nonspecific and present in 5% of older patients in absence of significant carotid disease.4 Other signs of the arterial disease may be present, such as arterial-based claudication, nonhealing ulcers, and post-prandial abdominal pain. The presence of coronary artery disease or aneurysmal disease should also be assessed in any vascular evaluation.4

Imaging

Imaging is not available for this case; however, carotid artery stenosis is typically first identified on imaging during workup for TIA using duplex ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). Diffusion-weighted MRI within 24 hours of symptom onset is recommended by guidelines set in 2009 by the American Heart Association/American Stroke Association (AHA/ASA) for TIA/CVA work up.6 CT is considered suboptimal for the evaluation of cortical injury in this presentation; however, it is recommended if MRI cannot be performed.

Guidelines also recommend routine imaging of the cerebral vasculature as part of the evaluation of patients with suspected TIA.6 It is reasonable to begin this identification with noninvasive methods such as ultrasound, CT angiogram, and/or MRI angiogram; however, if these provide an unclear picture, cerebral angiography may be needed.6 

It is important to quantify the degree of stenosis present as this will decide management. There are several comparable methods to do this. The North American Symptomatic Carotid Endarterectomy Trial (NASCET) method compares the lumen at the most stenotic portion of the vessel with the normal lumen distal to the stenosis.3 This method is used to stratify patients in mild (<50%), moderate (50–69%), and severe (70–99%) stenosis.3

Natural History

Like other atherosclerotic conditions, carotid artery stenosis is progressive, with a larger atherosclerotic burden presenting higher risk and more severe symptoms. Without treatment, severe narrowing will lead to embolic stroke and decreased survival.4 Nearly one in four strokes is in patients who have had previous strokes.1

Options for Treatment

Management decisions for carotid artery stenosis depend on the degree of stenosis, health of the patient, and whether the patient is symptomatic. Medical treatment is recommended for all patients with antiplatelet, antihypertensive, and statin therapy.4 Risk factor management includes quitting smoking, exercise, and weight loss.4

Options for severe carotid artery disease include CEA and carotid artery stenting (CAS). Both provide comparable results, and the decision must be individualized to the patient.4 Regardless of endarterectomy or stenting, medical management is continued indefinitely.4 

For symptomatic patients with severe stenosis, an endarterectomy is always recommended. Some guidelines recommend CEA over CAS for this patient population, especially if >70 years old.7 Symptomatic patients with moderate stenosis are also generally recommended for endarterectomy, though the benefit is considered less.7 Patients with mild stenosis or complete carotid occlusion have not been shown to benefit and are not recommended for standard internal carotid endarterectomy.7

For asymptomatic disease, there is less consensus on treatment. Guidelines generally recommend endarterectomy for asymptomatic patients with severe stenosis provided the patient is low risk for surgery and has a predicted life expectancy of at least 3–5 years.7

Rationale for Treatment

The patient discussed was found to be symptomatic with a 95% stenosis of the left internal carotid, necessitating the need for endarterectomy. His medications and lifestyle recommendations were reviewed and he was scheduled for CEA one week after the initial presentation with the goal of preventing future stroke.

Special Considerations

There are some groups for whom CEA is relatively contraindicated. Those are patients with a history of radiation treatment to the head and neck due to the diffuse nature of their plaque, prior neck surgery overlying the carotid artery, and high carotid bifurcation; these patients can benefit from stenting.8 Patients with significant carotid artery stenosis are likely to have other significant risk factors for other cardiovascular diseases, which may impact the decision to have surgery. 

Discussion

This case presents a 64-year-old male with significant cardiovascular risk factors and intermittent neurological symptoms. Significant stenosis of the left internal carotid artery was identified, and CEA with the placement of a synthetic graft was performed. 

CEA is done with an incision along the anterior border of the sternocleidomastoid muscle. After dissection to the carotid sheath, a longitudinal incision is made along the carotid artery, and the plaque is removed. The artery is reconstructed with patch angioplasty. Patching has shown lower rates of recurrent stenosis and perioperative stroke compared to primary repair;910 however, primary repair can also be safe.11 Patches of synthetic material, bovine pericardium, and venous graft have shown similar short- and long-term outcomes.12

A less studied method of CEA is eversion endarterectomy. In eversion CEA, the artery is transected, and the stenosed portion is removed, creating an end-to-end anastomosis.13 It is believed that this method reduces ischemia and total operating times with similar outcomes to conventional CEA.13 Shunting can be performed during eversion endarterectomy but it is more technically demanding.

The carotid artery is clamped during surgery, risking intraoperative embolism or cerebral hypoperfusion. To mitigate this, a shunt may be placed routinely or selectively when intraoperative neuromonitoring indicates cerebral hypoperfusion. The neurological status of the patient may be monitored using several methods depending on surgeon preference and capabilities of the facility. Mixed data have not shown a benefit from shunting; however, more powerful studies are warranted.14–16 Longer cross-clamping time is a predictor for delayed neurocognitive recovery following CEA, regardless of shunting.17

Patients are monitored postoperatively for strict blood pressure control to prevent complications. Low systolic blood pressure may lead to cerebral ischemia, while high blood pressure may cause neck hematoma. A drain may be placed to avoid hematoma. Drain and surgical dressing are removed on postoperative day 1 or 2. In addition to blood pressure, patients are monitored for severe headache, stroke, and myocardial infarction. Outpatient CEA may be safe if the patient is not undergoing general anesthesia,18 but most patients will spend 1–3 days in the hospital. Patients are followed with a repeat duplex ultrasound at six weeks following surgery and then at six-month intervals.4

This case illustrates the significance of CEA in the treatment of carotid artery stenosis. Carotid atherosclerosis is insidious, with stroke symptoms the first indication of occlusive disease.5 In those presenting with symptoms, the risk of recurrent stroke is more than 18% in 30 days, highlighting the importance of treatment in preventing further morbidity and mortality.5 

The first known successful attempt at surgical revascularization occurred in 1954, and enthusiasm for the procedure has steadily grown in the decades since then.2 Over time, questions arose over the efficacy and complication rates of the procedure, and which patients would benefit most. 

The NASCET established that symptomatic patients with severe stenosis, defined as 70–99%, obtained the greatest benefit to CEA.23 These patients saw an absolute risk reduction of 17% compared with medical management alone in the risk of ipsilateral stroke two years following surgery, with statistically significant benefit continuing at 8-year follow-up.2 Those with moderate symptomatic stenosis, 50–69%, saw a decreased but still statistically significant improvement in outcomes, while those with less than 50% stenosis saw no benefit to CEA.3

CEA is of the highest benefit when performed after 48 hours but within 14 days of symptom onset.7 There is no consensus on the appropriate interval from thrombolysis to CEA, with some studies showing an increased risk of stroke and/or death if CEA is performed within 72 hours of tPA administration.19

An increasingly accessible alternative to CEA is CAS. The Carotid Revascularization Endarterectomy vs. Stenting Trial (CREST) compared the outcomes of patients receiving stenting with those receiving CEA.20 CREST found no significant difference in rates of periprocedural stroke, myocardial infarction, death, or subsequent ipsilateral stroke at 4-year follow-up.20 The revascularization methods came with their own periprocedural complications, with a lower incidence of periprocedural stroke in CEA and a lower incidence of MI in stenting.20 It is generally thought that younger patients may be better candidates for stenting, while older patients may derive more benefit from CEA.20 This topic is under continued study in the CREST-2 and other trials.

Recent advancements in the medical management of atherosclerosis risk factors have necessitated the need for new studies into the effects and benefits of CEA. The CREST-2 trial is currently underway, comparing modern medical management with CEA and CAS.

Other frontiers in the treatment of carotid stenosis include the use of advanced imaging and big data to identify asymptomatic and symptomatic patients who are at the greatest long-term risk of stroke and may benefit from revascularization.7

Equipment

No special tools.

Disclosures

Nothing to disclose.

Statement of Consent

Massachusetts General Hospital has given its consent for the cadaver referred to in this video to be used for the education of healthcare professionals and is aware that information will be published online. 

Citations

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    https://doi.org/10.1056/NEJM199811123392002
  3. Beneficial Effect of Carotid Endarterectomy in Symptomatic Patients with High-Grade Carotid Stenosis. N Engl J Med. 1991;325(7):445-453.

    https://doi.org/10.1056/NEJM199108153250701
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    https://doi.org/10.1056/NEJMcp1214999
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    https://doi.org/10.1161/STROKEAHA.108.192218
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    https://doi.org/10.1016/s0741-5214(98)70353-2
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    https://doi.org/10.1016/s0895-7967(04)00044-4
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    https://doi.org/10.1177/0218492318788777
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    https://doi.org/10.1177/1708538120922098
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