Case Files Surgery, (LANGE Case Files) 4th Ed.

SECTION II. Clinical Cases

CASE 33

During an office visit, a 66-year-old man tells you that 1 week ago he experienced weakness in his right hand at work that resulted in a temporary inability to write or hold a pen. These symptoms persisted for approximately 45 minutes and resolved without further recurrence. The patient’s past history is significant for hypertension and coronary artery disease with stable angina. He has a history of 45-pack-year smoking. His medications include aspirin, nitrates, and a β-blocker. On examination, bruits can be heard over both carotid arteries. The results from the cardiopulmonary examination and the remainder of the physical examination are unremarkable. You obtain a duplex ultrasonogram of the carotid arteries that reveals an 80% narrowing of the left carotid artery and a 95% narrowing of the right carotid artery.

Images What is the most likely diagnosis?

Images What is the best therapy?

Images What is the optimal timing for treatment?

ANSWERS TO CASE 33: Carotid Artery Disease

Summary: A 66-year-old man presents with signs and symptoms suggestive of a recent transient ischemic attack (TIA) involving the left cerebral hemisphere. He has evidence of severe bilateral carotid stenoses as confirmed by a duplex scan.

• Most likely diagnosis: Bilateral carotid artery stenoses with a history of a left hemispheric TIA.

• Best therapy: The patient should be immediately placed on “best medical management,” which includes smoking cessation, blood pressure control, statin therapy to reduce LDL below 70 to 100 mg/dL, initiation of extended-release dipyridamole for combination antiplatelet therapy, and staged bilateral carotid endarterectomies (CEAs), beginning with the left (symptomatic) carotid artery.

• Optimal timing of treatment: The current recommended timing for CEA for patients with TIA is within 2 weeks of the event.

ANALYSIS

Objectives

1. Understand the natural history and evaluation of asymptomatic carotid bruits.

2. Be familiar with the medical and surgical treatment of patients with asymptomatic carotid stenosis and symptomatic carotid stenosis.

3. Understand the current role of medical, open-operative, and endovascular management of carotid stenosis.

Considerations

This patient provides a history that is fairly classic for TIA; however, TIA symptoms are not always easy for patients or physicians to recognize. Because the disability is frequently minor and short-lived, patients frequently attribute the symptoms to fatigue or other reasons and fail to bring them to the physician’s attention. Neurologic events arising from carotid disease are almost always unilateral, with the exception of speech impediment. After reviewing the initial history and physical examination, it is also important to look for evidence of coronary artery disease and atherosclerotic disease involving other parts of the vascular system. This particular patient has bilateral carotid disease. Because of the immediate- and long-term increased risk of strokes in this patient, the patient’s medical therapy should be optimized, and this would include the initiation of statin to improve lipid profile, addition of dipyridamole. Surgical treatment should be directed toward the symptomatic side first, and this should be optimally performed within 2 weeks of the TIA. Once he has recovered from his left CEA, he should undergo an asymptomatic right CEA. Both sides meet operative stenosis criteria, but the symptomatic side is addressed first because it is the higher-risk lesion to leave on conservative therapy.

APPROACH TO: Carotid Artery Disease

DEFINITIONS

ABCD SCORING SYSTEM: This is a five-factor scoring system to help stratify stroke risks in symptomatic patients. Age ≥Images point. Blood pressure ≥140/90 mm Hg = 1 point. Clinical features: unilateral weakness = 2 points and speech impairment without weakness = 1 point. Duration of TIA: >60 minutes = 2 points and 10 to 59 minutes = 1 point. Diabetes mellitus = 1 point. Stroke risks based on scores: Scores of 0 to 3 points are associated with 1.2% stroke risk in 7 days; scores of 4 to 5 points are associated with 5.9% risk of stroke in 7 days; scores of 5 to 6 points are associated with 11.7% risk of stroke in 7 days.

CLINICAL APPROACH

Stroke is the third leading cause of death in the United States and the leading cause of disability for adults, and extracranial internal carotid stenosis is estimated to be responsible for 30% of all acute strokes. Cerebrovascular disease management involves a classic state of balancing the risks of intervention with the risks of medical treatment. The conundrum is that the main complication of both modes of management is the same: stroke. The recommendations for operative and/or percutaneous interventions versus medical management have continued to evolve over the past two decades, as advances in interventions and medical management have evolved. As the result, some of the management recommendations that were derived from highly publicized randomized controlled trials are no longer applicable.

As a general rule, the more severe the stenosis in a given situation, the higher the incidence of symptoms. A bruit represents turbulent blood flow that resonates at an audible frequency. The presence of a cervical bruit does not necessarily indicate high-grade stenosis. In fact, only 50% of patients with carotid bruits have carotid stenoses >30%, and only 25% of patients with bruits have stenoses >75%. Duplex ultrasonography can be very accurate in confirming the presence of significant carotid disease. However, this is an operator-dependent procedure. The accuracy of stenosis grading should be at the highest level if a surgeon plans to recommend treatment based on duplex ultrasonography alone. If there is question of stenosis grade on ultrasonography, other tests are needed to help guide the therapy. This could be a magnetic resonance angiogram, or a CT reconstruction angiogram. An additional workup for a patient with carotid disease should include a thorough assessment of cardiopulmonary risks.

During the 1990s and early 2000s, patient selection criteria for medical or surgical management were largely based on the reported findings from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) published in 1991, the Asymptomatic Carotid Atherosclerosis Study (ACAS) published in 1995, and the Asymptomatic Carotid Surgery Trial (ACST) published in 2004. The findings from these studies supported the use of CEA for all patients with symptomatic stenoses >70% and patients with asymptomatic stenoses >60%. The findings from the ACAS and ACST trials demonstrated approximately 2% per year incidence of ipsilateral ischemia with medical management for asymptomatic patients, and CEA reduced the risk of stroke by 1% per year over a 5-year time period (Table 33–1).

Table 33–1 • SURGICAL VERSUS MEDICAL THERAPY IN CAROTID DISEASE

Images

Since the completion of ACAS and ACST, there have been some dramatic advances in medical management. It has been recently shown that patients with asymptomatic carotid artery stenoses on best medical management have an annual stroke risk of 0.34%, which is significantly lower than the reported annual stroke risk of 2% among medically managed patients during ACAS and ACST. Given the improvements in medical management and the marginal benefits of CEA in asymptomatic patients, the indications for carotid revascularization in asymptomatic patient have become highly controversial. For patients with symptomatic stenoses ≥70%, interventions in the form of carotid endarterectomy (CEA) or carotid artery stenting (CAS) are still indicated.

What has made management decisions for asymptomatic patients even more difficult is that there is a great deal of variability in hospital and operative complication rates associated with surgical and percutaneous interventions. If the particular surgeon and hospital have a safety record equal to or better than the perioperative complication rates observed during the trials, recommendations based on trial stenosis grades are fair and reasonable. However, if a surgeon or hospital has a complication rate greater than 5% with symptomatic patients or greater than 2% with asymptomatic patients, CEA should not be recommended aggressively. Many adjuncts are available to reduce the risk of perioperative stroke. The use of an intraluminal shunt, cerebral monitoring, and a patch angioplasty closure all can make CEA safer. The majority of patients who undergo CEA are home from the hospital in less than 24 hours.

Current Status of Carotid Angioplasty/Stenting

The short-term safety of CAS has been improved with the recent introduction of cerebral protection devices that are deployed during the procedure to trap embolic debris. The Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial result was reported in 2002, in which patients with more than 80% asymptomatic stenosis and more than 50% symptomatic stenosis and high-risk operative profiles were randomized to stenting versus endarterectomy. This trial reported 30-day death and major complication rates favoring stenting. In 2008, the 3-year follow-up results from the SAPPHIRE trial suggest no significant differences in long-term outcome between the treatment groups, thus suggesting that CAS may be a reasonable approach for appropriately selected high-risk patients. The findings of this trial have been questioned by some practitioners because the trial included a large percentage of asymptomatic, high-risk patients who were not considered appropriate candidates for intervention.

COMPREHENSION QUESTIONS

33.1 A patient has a 4-minute period of documented expressive aphasia that completely resolves. A workup reveals an 80% to 85% left internal carotid stenosis. A 50% right internal carotid stenosis is present. Which of the following is the most appropriate care?

A. Right CEA

B. Left CEA

C. Aspirin therapy at 81 mg/d

D. Aspirin therapy at 325 mg/d

E. Coumadin

33.2 An 84-year-old female patient with diabetes and class IV congestive heart failure presents in the office with a right neck bruit. Duplex sonography reveals a 50% to 75% stenosis in the right carotid artery. Which of the following is the most appropriate treatment?

A. Right CEA

B. Aspirin at 325 mg/d

C. Aspirin at 325 mg/d and repeated studies in 6 months

D. Confirmatory imaging with magnetic resonance angiography

E. Right CAS

33.3 A 71-year-old man suffers a moderately dense cerebrovascular accident (CVA) affecting his right arm and leg. He initially was hemiplegic. However, over the last 3 weeks he has recovered 80% of the strength in his right leg and 80% of the strength in his right arm. It has been 8 weeks since his stroke. A workup reveals a 95% stenosis in his left internal carotid artery; his right internal carotid artery is occluded. Which of the following is the most appropriate treatment?

A. Aspirin at 325 mg/d

B. Right CEA

C. Aspirin and dipyridamole

D. Warfarin anticoagulation therapy

E. Left CEA with intraoperative intraluminal shunting

33.4 A 66-year-old woman underwent right CEA for symptoms of cerebrovascular insufficiency (right eye visual loss and left arm weakness that resolved) confirmed by a bruit and 90% stenosis on angiography. On postoperative day 1, the patient expired. Which of the following was the most likely cause of her death?

A. Myocardial infarction

B. Vascular surgical failure leading to exsanguination

C. Pulmonary embolism

D. Electrolyte imbalances

E. Infections

33.5 Which of the following statements regarding CAS is most accurate?

A. In high-risk patients, carotid stenting resulted in better early outcome than CEA.

B. Cerebral protection devices have not reduced operative stroke rate related to carotid stent placement.

C. The 3-year outcome comparing CEA to stent placement has favored CEA.

D. The success of carotid stenting with cerebral protection has extended operative indications to include asymptomatic patients with 50% carotid stenosis.

E. With the introduction of CAS, the indications for CEA have expanded.

ANSWERS

33.1 B. Left CEA. The patient has a high-grade (exceeding 70%) stenosis in the appropriate artery distribution for his symptomatic TIA. Although aspirin therapy is essential for both operative and nonoperative patients with cerebrovascular disease, this patient meets the operative criteria. The definitive dose of aspirin is still debatable. There is no clear indication that systemic anticoagulation reduces the risk of strokes in patients with carotid artery stenosis.

33.2 D. Confirmatory magnetic resonance angiography. This is a medically high-risk patient who is asymptomatic and has an equivocal duplex stenosis. If the stenosis actually turns out to be 75%, a careful discussion of the risks and benefits can be held with the patient. However, it still would be prudent to continue conservative management in this high-risk asymptomatic individual. In general, CEA is not recommended for asymptomatic patients with life expectancy of less than 5 years or expected combined perioperative death and stroke rate of greater than 3%. CAS is not indicated for asymptomatic patients.

33.3 E. Left CEA using an intraluminal shunt. This is a symptomatic patient with significant recovery from a left hemispheric CVA. His highest risk of recurrent stroke is during the first 6 months following the first event. As such, his contralateral occlusion is not a contraindication to CEA. Based on his presentation, most surgeons would use an intraluminal shunt for his CEA. Antiplatelet therapy with aspirin and dipyridamole is more efficacious than aspirin alone for stroke prevention, but medical therapy alone is not adequate for this patient.

33.4 A. Acute myocardial infarction and perioperative stroke are the two most common severe complications following carotid CEA. This knowledge should encourage preoperative evaluation for cardiovascular disease, and also monitoring for early symptoms and signs postoperatively. Symptomatic patients with very high risk of developing perioperative cardiac morbidity and mortality could be considered for CAS.

33.5 A. The SAPPHIRE trial showed that high-risk patients with asymptomatic stenoses >80% and symptomatic stenoses >50% had lower 30-day morbidity and mortality associated with stenting in comparison to CEA. In the 2008 report of the 3-year follow-up of SAPPHIRE patients, no significant difference in outcome was reported between CEA and stenting patients, suggesting that the intermediate-duration outcome of stenting is perhaps equivalent to CEA. CAS is still associated with significant periprocedural morbidity; therefore the availability of CAS does not change the indications for carotid revascularization.

CLINICAL PEARLS

Images The success and complication rates associated with CEA and carotid stenting are highly operator dependent; therefore, it is important to consider these factors prior to recommending therapy.

Images Embolization is the most common cause of a cerebral ischemic event related to carotid stenosis.

Images Dizziness, syncope, and confusion are almost never caused by carotid artery stenoses.

REFERENCES

Gurm HS, Yadav JS, Fayad P, et al. Long-term results of carotid stenting versus endarterectomy in high-risk patients. N Eng J Med. 2008;358:1572-1579.

Lanzino G, Tallarita T, Rubinstein AA. Internal carotid artery stenosis: natural history and management. Semin Neurol. 2010;30:518-527.

Lin PH, Kougias P, Bechara C, Cagiannos C, Huynh TT, Chen CJ. Arterial disease. In: Brunicardi FC, Andersen DK, Billiar TR, et al, eds. Schwartz’s Principles of Surgery. 9th ed. New York, NY: McGraw-Hill; 2010:701-775.

Perler BA. Carotid endarterectomy. In Cameron JL, Cameron AM, eds. Current Surgical Therapy. 10th ed. Philadelphia, PA: Elsevier Saunders; 2011:730-734.