Renal artery stenosis

Carotid artery stenosis is characterized by atherosclerotic changes, plaquing, ulcerations, and a progressive narrowing of the carotid vessels. Stenosis is most significant at the carotid bifurcation, also known as the carotid bulb, where the common carotid vessel branches into the internal and external carotid arteries (Figure 1).

[FIGURE 1 OMITTED]

EPIDEMIOLOGY

Carotid artery stenosis can be linked directly to 20% to 30% of the 500,000 cerebral vascular accidents (CVAs) (ie, strokes) that occur in the United States each year. (1) Stroke is the third most common cause of death in the United States, so the mechanisms of acute arterial occlusion and embolization resulting from carotid artery stenosis are significant health care issues. (2) The risk of stroke and transient ischemic attacks (TIA) increases depending on the percentage of stenosis of the carotid artery:

* 50% stenosis increases the risk of TIA and stroke by 4%,

* 75% stenosis increases the risk of TIA and stroke by 10.5% to 18%, and

* 80% stenosis increases the risk of TIA and stroke by 35% after six months and 46% after one year. (3) Specific characteristics of atheromas (eg, soft and/or ulcerative plaquing) also increase the risk of stroke. (4)

ANATOMY AND PHYSIOLOGY

Cerebral blood flow is provided by the internal carotid and vertebral arteries. The left common carotid artery branches directly off the transverse aortic arch, and the right common carotid artery branches off the brachiocephalic artery, which originates at the transverse aortic arch. The common carotid arteries branch into the internal and external carotid arteries. The internal carotid artery supplies blood to the middle ear, brain, hypophysis, orbit, and choroid plexus of the lateral ventricle. (5) The external carotid artery supplies blood to the neck, face, and skull.

The internal carotid arteries are located in the the anterior aspect of the neck and provide the greatest proportion of blood flow to the brain. Entering the cranium through the base of the skull, the internal carotid arteries pass through the cavernous sinus and divide into the anterior and middle cerebral arteries. The internal carotid arteries--along with the posterior cerebral, posterior communicating, anterior cerebral, and anterior communicating arteries--form the Circle of Willis at the base of the brain. (6) Collateral blood flow through the Circle of Willis allows the body to compensate for reduced blood flow from any of the major contributing blood vessels.

Cerebral blood flow is determined by cerebral perfusion pressure divided by cerebral vascular resistance. Factors that regulate cerebral blood flow include

* blood pressure,

* metabolic demands,

* partial pressure of carbon dioxide, and

* partial pressure of oxygen. (7)

Tissue pressure receptors (ie, pressoreceptors, mechanoreceptors) in both the aortic arch and the carotid arteries are responsible for the baroreceptor reflex, which facilitates blood pressure and heart rate changes. These receptors increase their rate of discharge when stretched by blood pressure elevations. Neural impulses are transmitted to the cardiovascular control centers in the medulla via the glossopharyngeal nerve (ie, ninth cranial nerve) from the carotid receptors and via the vagus nerve (ie, 10th cranial nerve) from the aortic receptors.

SIGNS AND SYMPTOMS

Carotid artery stenosis may be either symptomatic or asymptomatic. Symptomatic patients present with a TIA, stroke in evolution, or completed stroke. A TIA is a neurological event that may last from several seconds to 24 hours. Symptoms of TIAs may vary from

* minimal loss of sensation in one hand;

* complete hemiparesis on the contralateral side to the carotid lesion; to

* amaurosis fugax, which is a temporary blindness on the ipsilateral side of the carotid lesion caused by embolization of the ophthalmic artery.

A stroke in evolution is when the neurological deficit progresses or fluctuates but never returns to normal. A complete stroke progresses to a stable deficit without a change in degree of symptomatology and lasts for more than 24 hours. A complete stroke usually manifests as an infarct on magnetic resonance imaging (MRI) or computerized tomography (CT) scan. (8)

Asymptomatic carotid artery disease is identified during routine physical examination by the presence of a carotid bruit or during duplex ultrasound screening of high-risk patients. A bruit is indicative of turbulent blood flow through a diseased artery. (9) Stenosis in the artery causes a swishing sound, which is heard as a bruit on auscultation and also may be felt as a thrill or slight vibration in the vessel on palpation. To prevent interference from tracheal sounds, caregivers use the bell of the stethoscope to auscultate for a bruit while the patient holds his or her breath for a few seconds. In a normal vessel, neither a bruit nor thrill should be identified; however, cervical bruits may be absent in more than one-third of patients with high-grade stenosis, and the frequency of bruits sharply decreases with stenosis greater than 90%. (10) Additionally, the presence or absence of a bruit is not indicative of TIA or stroke rate. (11) A carotid bruit also may be indicative of transmitted sounds from cardiac structures (eg, aortic valve stenosis, severe aortic valve regurgitation, ruptured chordae tendinae of mitral valve). (12) Based on this, presence of a bruit is not reliable criteria with which to independently diagnose carotid artery stenosis; however, its presence indicates the need for further investigation. (13)

DIAGNOSIS

If a patient presents with symptoms of carotid artery stenosis, the cause must be identified. Ischemic stroke and TIAs may result from either cardiogenic, vascular, or hematological causes. Multiple potential causes of ischemic stroke and TIAs are listed in Table 1. After a thorough history and physical are obtained, patients presenting with signs and symptoms of TIA or risk factors for ischemic stroke should undergo radiologic evaluation of the carotid vessels. (14)

Diagnostic tests. Diagnostic tools specific to carotid artery stenosis include the duplex ultrasound study, contrast arteriography, and magnetic resonance arteriography (MRA). Duplex ultrasound uses B-mode two-dimensional imaging, color flow technology, and velocity waveform analysis to determine the percentage of stenosis in the vessel lumen. (15) This quick and noninvasive study has a high degree of sensitivity for diagnosis of carotid artery stenosis. Despite its operator-dependent variability and inability to provide information on intrathoracic and intracranial vessels, some institutions use it as the sole test before surgical intervention. Studies supporting the sole use of duplex ultrasound to identify carotid artery stenosis use institutional validation and ongoing quality assurance programs. (16) Although routine screening for carotid artery stenosis is not required at this time, studies support the limited use of duplex ultrasound screening for high-risk patients. (17) In the hands of a skilled operator, the carotid duplex ultrasound may be a good determinant of cavitated, gelatinous, "soft" atheroma, which may increase a patient's risk of stroke. (18)

The use of contrast arteriography is supported as the preferred test in all preoperative evaluations by the North American Symptomatic Carotid Endarterectomy Trial (NASCET). (19) This invasive examination, which requires the use of contrast media injected into arterial circulation, provides detailed anatomy and determination of the extent of disease in not only the carotid vessels but also the intracranial and intrathoracic vessels. (20) Although it provides additional data, contrast arteriography costs more and may incur complications (ie, stroke, arterial dissection, pseudoaneurysm formation, infection). (21)

Magnetic resonance angiography also can be used to provide noninvasive evaluation of arterial vessels. This examination is particularly helpful when evaluating patients who

* are allergic to contrast media,

* have renal insufficiency,

* desire a noninvasive test, or

* have been exposed to large quantities of contrast medium recently during other examinations, which may contribute to renal failure. (22)

Although MRA has many advantages, it is not readily available in some areas and may not be an option for patients who

* have implanted metallic devices because movement of implants may cause injury,

* may be unable to lie still, or

* cannot tolerate the claustrophobic effects of the testing environment. (23)

Despite its accuracy in determining occlusive disease, patient motion may decrease clarity and resolution in 10% to 15% of studies. (24)

TREATMENT

Treatment for patients with carotid artery stenosis depends on the severity of the stenosis and the patient's symptoms. Accordingly, patients may be treated medically or surgically. Carotid endarterectomy is the surgical treatment of choice at this time.

Medical treatment The goal of medical treatment is to minimize symptoms and reduce the risk of stroke while optimally controlling concurrent disease (eg, hypertension, diabetes mellitus, cardiac disease, hyperlipidemia). Medical treatment also includes

* weight reduction,

* smoking cessation,

* limiting alcohol consumption,

* antiplatelet therapy, and

* follow-up duplex ultrasound scans to monitor progression of disease. (25)

Just as important is patient education about early identification of TIA and nondisabling stroke symptoms. Patients must be able to recognize the symptoms and understand the importance of immediately reporting these symptoms to health care providers.

Surgical patient selection guidelines. Much debate has taken place regarding the appropriate patient selection criteria for carotid endarterectomy. During the 1980s, three prospective randomized clinical trials (ie, NASCET, European Carotid Surgery Trial [ECST], Carotid Endarterectomy and Prevention of Cerebral Ischemia in Symptomatic Carotid Stenosis Study) studied carotid endarterectomy versus best medical management for the treatment of patients with ipsilateral carotid artery stenosis. The Veterans Affairs Cooperative Symptomatic Trial produced similar results as these studies but was halted when results from NASCET and ECST studies were released. (26) Based on this research, the American Heart Association (AHA) concludes that carotid endarterectomy

* is beneficial for symptomatic patients with a recent nondisabling neurological event and ipsilateral stenosis of 70% to 90%,

* has uncertain benefit for symptomatic patients with 30% to 60% stenosis, and

* has not been proven beneficial for symptomatic patients with 0% to 29% stenosis. (27)

For patients with asymptomatic carotid stenosis, the AHA based its position on the Asymptomatic Carotid Atherosclerosis Study, taking into consideration not only surgical risk but also life expectancy rates. Surgical risk data are used to develop patient selection criteria based on age, present blood pressure, history of hypertension, smoking, coronary disease, diabetes, and hyperlipidemia (Table 2). Additional recommendations regarding concomitant coronary bypass surgery and contralateral disease can be obtained from the AHA guidelines. (28)

The AHA further states that the complication rate of carotid endarterectomy surgery should be kept extremely low to maintain its benefits over those of medical therapy. The recommended combined perioperative neurological morbidity and mortality rates for

* asymptomatic patients is 3%,

* symptomatic patients with TIAs is 50,

* symptomatic patients with recovery from CVA is 70, and

* patients with recurrent stenosis is 10%. (29)

The literature supports referring patients who require carotid endarterectomy to programs with high volumes and whose surgeons have a low rate of complications intraoperatively and postoperatively. (30) Data supporting endarterectomy in patients who have symptomatic or asymptomatic carotid artery stenosis have led to a major increase in the number of carotid endarterectomy procedures performed on high-risk patients and to continued improvement of results. (31)

Additional studies regarding the timing of carotid endarterectomy are ongoing. Some studies support performing carotid endarterectomy on patients with carotid artery stenosis after a recent stroke when intracranial bleeding and mass lesions have been ruled out. Other studies, however, strongly indicate that early revascularization precipitates hemorrhage in the infarcted area and, therefore, contraindicates endarterectomy. (32)

CAROTID ENDARTERECTOMY

The first successful carotid endarterectomy was performed in 1953, and it has since evolved as the "gold standard" for prevention of stroke from severe carotid artery stenosis. (33) Before 1953, procedures such as stellate ganglion block, cervical sympathectomy, thrombectomy of occluded carotid arteries, and carotid bifurcation ligation, were used. (34) One author described observed relationships between atherosclerotic carotid disease and stroke. The carotid endarterectomy procedure is based on these observations. (35) The procedure has been modified and refined throughout the years, resulting in a variety of acceptable surgical methods, and carotid endarterectomy soon may be performed as outpatient surgery.

Preoperative preparation. The preadmission process begins after the surgeon and patient decide that surgery is the treatment of choice. When the patient is scheduled for surgery, the surgical team is notified of any departure from the surgeon's normal routine to include the need for

* a specific anesthetic,

* electroencephalography (EEG) monitoring,

* cerebral oximetry monitoring,

* pulmonary artery catheter monitoring, or

* intra-arterial shunting.

A cardiac evaluation is needed to rule out existing disease that could complicate the planned anesthesia and surgical interventions. This evaluation is particularly important due to the frequency of comorbid cardiac disease in this patient population. The patient usually is scheduled for a preadmission visit the day before surgery, at which time the nurse performs an admission assessment and documents known allergies. One or more of the following tests are ordered depending on the patient's age and health status:

* chest x-ray,

* electrocardiogram,

* urinalysis, and

* blood tests, including complete blood count, potassium, creatinine, blood urea nitrogen, prothrombin time, partial prothrombin time, and magnesium.

Results are documented on the patient's chart, and abnormal results are reported to the surgeon or his or her designated assistant. A blood type and screen is performed, and the surgeon obtains informed consent from the patient for the surgical procedure, anesthesia, and blood transfusions, if needed. The nurse provides the patient with a 4% chlorhexidine gluconate scrub and instructs the patient to shower with it the night before surgery. The nurse also provides the patient with education pamphlets after discussing the inpatient unit, the surgical procedure, postoperative pain control, and blood and blood-product transfusion. Other topics discussed include the date and time of the surgical procedure, time of arrival, postoperative respiratory care (eg, "turn, cough, deep breathe" exercises, use of the inspirometer), progression of diet and activity, and frequency of postoperative vital signs and neurological checks. The nurse instructs the patient to take all prescribed medications before admission except warfarin sodium, aspirin, aspirin-containing products, antiplatelet medications, and diabetic medications.

The patient is admitted to the cardiovascular unit the day of surgery. After admission, the nurse verifies cardiovascular, respiratory, neurological, gastrointestinal, genitourinary, nourishment, psychosocial, skin, and safety assessments. He or she then measures the patient's vital signs, which will be done every four hours preoperatively, and performs the preoperative surgical skin prep, including shave and scrub with 4% chlorhexidine gluconate.

Intraoperative period. The anesthetic options for carotid endarterectomy are diverse, ranging from local infiltration or cervical block with or without sedation to general anesthesia. The advantage to local or cervical block anesthesia is that the surgeon can evaluate the patient's mental status and cerebral tolerance to clamping of the carotid vessels throughout the procedure. The patient's motor status also can be evaluated, ensuring adequate cerebral circulation. The disadvantages to local or cervical block anesthesia are related primarily to patient anxiety, restlessness, and altered level of consciousness. These problems disturb surgical team members and pose additional problems if the patient becomes anoxic, requiring general anesthesia and intubation during the procedure. Transitioning to general anesthesia disrupts the surgical procedure and could jeopardize the sterility of the surgical field.

Starting the procedure with general anesthesia avoids these problems and allows control of the patient's airway and activity. An additional advantage to general anesthesia is that halogenated anesthetic agents may be used, which have been shown to increase cerebral blood flow and decrease cerebral metabolic demand, allowing improved tolerance of carotid clamping. (36) The major disadvantage to general anesthesia is the inability to monitor the neurological status of the patient throughout the procedure. Although the anesthetic approach depends largely on surgeon preference, the decision often is influenced by the anesthesia care provider, the patient's health status, and patient preference.

Intraoperative EEG and cerebral oximetry may be used to monitor cerebral perfusion during carotid endarterectomy, especially during general anesthesia. These monitoring devices allow surgical team members to use an intra-arterial shunt if clamping the carotid vessels causes cerebral hypoxia (Figure 2).

[FIGURE 2 OMITTED]

Positioning. The surgeon, anesthesia care provider, and circulating nurse position the patient supine with moderate hyperextension of the neck using a shoulder roll with the patient's face turned to expose the surgical side of the neck. Cervical arthritis and limited joint mobility must be taken into consideration when positioning these patients. Extreme hyperextension actually may impede exposure by tightening the sternocleidomastoid muscle and limiting mobility of the common carotid artery and the bifurcation. (37) Slight elevation of the head of the bed will improve the presentation of the surgical site while decreasing venous pressure and minimizing incisional bleeding.

Incisional options. Two surgical incisions are used in carotid artery endarterectomies (Figure 3). The first option is a vertical incision parallel to the anterior border of the stemocleidomastoid muscle along a line connecting the sternal-clavicular junction with the mastoid process. (38) The exact length and placement of the incision are determined by the location of the carotid bifurcation and the extent of the disease. The advantage of this incision is that it can be extended distally and proximally to provide additional exposure, if needed. The second option is a horizontal incision that is oblique (ie, almost perpendicular) to the carotid artery and placed in a neck crease. (39) This incision is more acceptable cosmetically and produces less local nerve damage. The disadvantage of this incision is that skin flaps must be raised, making surgical exposure more challenging, and the incision cannot be extended in the proximal and distal arterial directions if needed later.

[FIGURE 3 OMITTED]

After the surgeon has made the initial incision, he or she extends it through the platysmal muscle layer and into the subplatysmal area. The fascia is incised, and the carotid sheath is located under the anterior border of the stemocleidomastoid muscle. As the sheath is entered, the internal jugular vein is dissected and retracted to expose the carotid vessels. The common facial vein is a landmark for the carotid bifurcation where it obliquely crosses the carotid to the internal jugular vein. The surgeon mobilizes this vein and ligates and divides it, which allows for dissection of the carotid vessels. The surgeon distally mobilizes and divides the belly of the digastric muscle, if necessary, to allow for adequate visualization of the internal carotid artery. Care is taken to preserve the ansa cervicalis and vagus nerves, which run parallel to the carotid vessels. Injury to the recurrent laryngeal nerve, a branch of the vagus nerve, may cause hoarseness secondary to temporary or permanent vocal cord paralysis. The hypoglossal nerve (ie, 12th cranial nerve), which passes across the internal and external carotid arteries, requires identification and protection during the procedure. Injury to this nerve causes lateral deviation of the tongue toward the surgical side during protrusion and can cause difficulty swallowing. When dissecting the carotid bifurcation, the surgeon may inject the tissues of the carotid body and sinus with 1% lidocaine to prevent a reflex vagal response resulting in bradycardia and subsequent hypotension. Additionally, care must be taken when dissecting the carotid vessels to avoid disturbing the atheromatous lesions causing fragmentation and subsequent embolization and stroke. The common carotid bifurcates into the internal and external carotid arteries. The superior thyroid artery lies at the beginning of the external carotid artery. The surgeon may encircle vessels with umbilical tapes and tourniquets to control blood flow later in the procedure (Figure 4). Smaller vessels may be controlled with double-looped silk ties or vessel loops.

[FIGURE 4 OMITTED]

Clamp time. After the anesthesia care provider establishes adequate systemic anticoagulation with heparin, the surgeon clamps or occludes the vessels by tourniquet and makes the arteriotomy (Figure 5). Heparin dosage and use of activated coagulation time (ACT) monitoring are surgeon dependent; however, adequate time for heparin circulation before clamping the arteries is required. Continuous observation for clotting, which may indicate inadequate anticoagulation, is required. Cerebral clamp time is monitored from this point until flow is reestablished with the use of an intraoperative shunt or the clamps are removed. It is crucial to maintain adequate blood pressure during common carotid clamping so that the Circle of Willis, if intact, can provide collateral blood flow to the brain during this time.

[FIGURE 5 OMITTED]

Carotid shunts. Intraoperative EEG, monitoring cerebral oximetry and back pressures, and inspecting for back bleeding are methods used to determine whether reestablishment of flow using a shunt during endarterectomy and suture closure of the vessel is necessary. Following are indications for the use of a shunt intraoperatively:

* changes indicating cerebral hypoxia on the EEG and cerebral oximetry monitors,

* low pressure in the clamped distal internal carotid artery, or

* poor back bleeding from an unclamped internal carotid artery.

There are many types of carotid shunts; however, the goal of temporary reestablishment of blood flow using a manufactured tube is the basic premise inherent to all designs. Although the use of a shunt may ensure reestablishment of blood flow, it is not without complications including

* intimal damage,

* air or thrombotic emboli, and

* decreased access to the vessel due to the presence of the shunt itself.

Arteriotomy. The surgeon makes the arteriotomy incision either longitudinally in the common carotid artery and into the internal carotid artery beyond the end point of the lesion to be endarterectomized (Figure 6) or transversely across the starting point of the internal carotid artery separating it from the common carotid (Figure 7). The surgeon performs the endarterectomy (ie, removal of atheromatous plaque) with the optimal plane lying between the diseased intima and the circular fibers of the arterial media (Figure 8). (40) It is essential to ensure a clean break in the distal vessel. Tacking stitches may be required at the distal point to prevent flap formation when flow is reestablished. It is necessary to create a smooth shelf at the proximal end of the endarterectomy in the common carotid artery where disease often progresses proximally beyond the accessible surgical area. When using the transverse arteriotomy, the endarterectomy of the internal carotid artery is achieved using an eversion method. Eversion endarterectomy requires turning back the arterial wall upon itself and applying traction to the atheromatous core or plaque as it is freed from the vessel wall. A smooth surface at the origin of the plaque is established before the vessel is drawn back to its normal position. The surgeon then completes the endarterectomy of the external carotid vessel, which often requires eversion. When endarterectomy is complete, the surgeon irrigates the area with heparinized saline and removes any loose debris to yield a smooth surface to the endarterectomized vessel (Figure 9).

[FIGURES 6-9 OMITTED]

Closure. The surgeon closes the vessel using a fine polypropylene suture. A vein or prosthetic patch may be used to increase the diameter of the vessel and decrease the reoccurrence of stenosis in small vessels. When the eversion method of internal carotid artery endarterectomy is used, the internal carotid artery is sutured to the bulb where it previously was removed (Figure 10). This procedure often is used when the internal carotid artery becomes kinked due to excess length. A portion of the internal carotid artery then is removed or the arteriotomy is extended to incorporate the excess length in the suture line. If a shunt is used, additional time without cerebral perfusion when the vessels are reclamped and the shunt is removed is needed to put the final sutures in place.

[FIGURE 10 OMITTED]

The incision is closed when reestablished flow has been verified by doppler ultrasound and homeostasis has been achieved (Figure 11). Protamine sulfate may be used to reverse anticoagulation based on surgeon preference. Drains may be used to prevent hematoma development in the postoperative period. Postoperative bleeding can cause hematomas, resulting in tracheal deviation and respiratory distress.

[FIGURE 11 OMITTED]

The perioperative nurse, working in conjunction with other surgical team members, develops and implements appropriate patient-specific nursing diagnoses and a plan of care for the patient undergoing carotid endartarectomy (Table 3). An RN first assistant (RNFA) with clinical expertise and training as a surgical first assistant often aids the surgical team during the procedure (Table 4). Each surgeon defines specific surgical skills used by the RNFA during carotid endarterectomy. Collaboration and interdependent relationships among the surgeon, RNFA, and patient are essential. To help prevent intraoperative complications, it is essential that the RNFA be knowledgeable in anatomy and physiology of the neck and carotid vessels, the carotid endarterectomy procedure, the use of intra-arterial shunting, and cerebral monitoring.

Postoperative recovery. In lieu of an intensive care stay, patients now are spending an extended stay in the postanesthesia care unit (PACU) (ie, two hours) to ensure cardiovascular and neurological stability. When PACU discharge criteria are met, the patient is moved to the cardiovascular unit where he or she remains overnight. If cardiovascular, respiratory, or neurological stability declines, the routine carotid endarterectomy care pathway is interrupted with an intensive care transfer. Postoperative care includes cardiovascular, respiratory, neurological, gastrointestinal, genitourinary, skin, and wound assessment upon return to the unit and every four hours after that. Additionally, vital signs and neurological assessments are performed

* on admission,

* every 30 minutes for one hour,

* every hour times four for four hours,

* every two hours times eight for 16 hours, and then

* every four hours until discharge.

The preoperatively prescribed medication regimen is resumed and IV therapy is monitored on admission and every hour. Nourishment, telemetry, pain management, safety, musculoskeletal, and education assessments are ongoing.

Discharge. Discharge criteria, usually met by early afternoon of the day after surgery, include

* stable vital signs for 24 hours,

* intact incision site,

* tolerating soft diet,

* ambulating with minimal assistance,

* pain control adequate with oral medications,

* afebrile,

* oxygen saturation greater than 91%, and

* a stable airway.

Neurological status, fever, signs and symptoms of infection, respiratory difficulties, and pain uncontrolled by oral medications are discussed with both the patient and his or her family members. The patient and family members are instructed to notify the surgeon immediately if there are any abnormalities. Additional discharge instructions include performing wound care, resuming preoperative medications, advancing from a diet of soft solids to preoperative diet, and participating in activities as tolerated.

Complications. Often patients undergoing carotid endarterectomy also have comorbid conditions, such as coronary artery disease, hypertension, or diabetes. Perioperative complications may include stroke, heart attack, and death. Postoperative complications include cranial nerve injury, hematoma, hypertension, hypotension, hyperperfusion syndrome, intracranial bleed, seizures, and recurrent stenosis. (41) Many of these complications are related directly to the early postoperative care of the patient. These patients require close postoperative supervision and have to avoid severe hypertension, restlessness, and vomiting, which can cause stress on the suture line and lead to postoperative bleeding. Swallowing and tongue control should be evaluated before patients are given oral fluids. Although studies may show that advanced age does not affect the results of carotid endarterectomy adversely, older adults with comorbid disease states may require longer postoperative recovery periods. (42)

Risk factors. Long-term postoperative care refers to controlling carotid stenosis risk factors, including hypertension, diabetes, high cholesterol, and smoking. Treatment includes the use of long-term antiplatelet medication therapy, and follow-up carotid ultrasound studies may be performed to monitor for restenosis or contralateral disease progression.

SUMMARY

Angioplasty, stenting procedures, and use of thrombolytic agents in the acute phase of evolving stroke are on the horizon for nonsurgical treatment of carotid artery stenosis. At present, carotid angioplasty and stenting are reserved for patients presenting as high-risk surgical candidates or those with lesions inaccessible by current carotid endarterectomy procedures. (43) Until these procedures have evolved to the point of equaling or surpassing the morbidity and mortality rates of surgical treatment, carotid endarterectomy will remain the "gold standard" treatment for severe carotid stenosis. (44)

NOTES

(1.) J R Eugene et al, "Carotid occlusive disease: Primary care of patients with or without symptoms," Geriatrics 54 (May 1999) 24-36.

(2.) Ibid, 24.

(3.) Ibid, 25.

(4.) Ibid.

(5.) B F Miller, C B Keane, Encyclopedia and Dictionary of Medicine and Nursing, (Philadelphia: W B Saunders, 1972) 72.

(6.) K L McCance, S E Huether, Pathophysiology: The Biologic Basis for Disease in Adults and Children, third ed (St Louis: Mosby, 1998) 401.

(7.) W E Hurford et al, eds, Clinical Anesthesia Procedures of the Massachusetts General Hospital, fifth ed (Philadelphia: Lippincott-Raven Publishers, 1998) 422.

(8.) Eugene et al, "Carotid occlusive disease: Primary care of patients with or without symptoms," 26.

(9.) C A Kirton, "Assessing for carotid bruit," Nursing 26 (October 1996) 55.

(10.) A Adelman, "Carotid artery stenosis: To screen or not to screen," American Family Physician 53 (Feb 1, 1996) 486-491.

(11.) Ibid, 491.

(12.) H M Seidel et al, Mosby's Guide to Physical Examination, third ed (St Louis: Mosby-Year Book, Inc, 1995) 367-443.

(13.) Eugene et al, "Carotid occlusive disease: Primary care of patients with or without symptoms," 25-26

(14.) Ibid, 26.

(15.) Ibid.

(16.) Ibid; J L Ballard et al, "Cost-effective evaluation and treatment for carotid disease," Archives of Surgery 132 (March 1997) 268-271.

(17.) C G Carsten III et al, "Use of limited color-flow duplex for a carotid screening project," American Journal of Surgery 178 (August 1999) 173-176; Adelman, "Carotid artery stenosis: To screen or not to screen," 486.

(18.) J E Castaldo, "Is carotid endarterectomy appropriate for asymptomatic stenosis? Yes." Archives of Neurology 56 (July 1999) 877-879.

(19.) Eugene et al, "Carotid occlusive disease: Primary care of patients with or without symptoms," 30.

(20.) Ibid; D J Bain et al, "Role of arteriography in the selection of patients for carotid endarterectomy," British Journal of Surgery 85 (June 1998) 768-770.

(21.) Bain et al, "Role of arteriography in the selection of patients for carotid endarterectomy," 768-770; Ballard et al, "Cost-effective evaluation and treatment for carotid disease," 268-271.

(22.) Eugene et al, "Carotid occlusive disease: Primary care of patients with or without symptoms," 29-30.

(23.) Ibid.

(24.) Eugene et al, "Carotid occlusive disease: Primary care of patients with or without symptoms," 29.

(25.) Ibid, 30-35; J Biller et al, "Guidelines for carotid endarterectomy: A statement for healthcare professionals from a special writing group of the stroke council," American Heart Association, http: //216.185.112.5/presenter.jhtml ?identifier= 1823 (accessed 19 Nov 2001); Castaldo, "Is carotid endarterectomy appropriate for asymptomatic stenosis? Yes." 877-879; S E Morey, "AHA updates guidelines for carotid endarterectomy," American Family Physician 58 (Nov 15, 1998) 1898-1904.

(26.) P N Riggs, J A DeWeese, "Carotid endarterectomy," Surgical Clinics of North America 78 (October 1998) 881-900.

(27.) Biller et al, "Guidelines for carotid endarterectomy: A statement for healthcare professionals from a special writing group of the stroke council"; Morey, "AHA updates guidelines for carotid endarterectomy," 1898-1904.

(28.) Ibid.

(29.) J S Yao, "Angioplasty and stenting for carotid lesions: An argument against," Advances in Surgery 32 (1999) 245-254.

(30.) D Bandyk, "Carotid Endarterectomy: The `gold standard' for prevention of stroke from severe carotid stenosis," Journal of the Florida Medical Association 84 (April/may 1997) 233; H J Barnett et al, "Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators," The New England Journal of Medicine 339 (Nov 12, 1998) 1415-1425; Castaldo, "Is carotid endarterectomy appropriate for asymptomatic stenosis? Yes" 878; R D Cebul et al, "Indications, outcomes, and provider volumes for carotid endarterectomy," JAMA 279 (April 22-29, 1998) 1282-1287; S Gaskie, "Carotid endarterectomy for symptomatic moderate stenosis," The Journal of Family Practice 48 (February 1999) 91.

(31.) J Brittenden et al, "Carotid endarterectomy before and after publication of randomized controlled trials," British Journal of Surgery 86 (February 1999) 206-210.

(32.) G E Mead et al, "Pilot study of carotid surgery for acute stroke," British Journal of Surgery 84 (July 1997) 990-992; P S Paty et al, "Timing of carotid endarterectomy in patients with recent stroke," Surgery 122 (October 1997) 850-855.

(33.) "DeBakey: The making of medical history," Baylor Medicine, http://www.bcm.tmc.edu/baylomed /Archives/November 1998/novem ber 1998.html (accessed 19 Nov 2001); Bandyk, "Carotid endarterectomy: The `gold standard' for prevention of stroke from severe carotid stenosis," 232.

(34.) Ibid.

(35.) Ibid; R S MacWalter, "A brief history of stroke treatment," http: //www.sol.co.uk/r/rsmacwalter /history.htm (accessed 19 Nov 2001).

(36.) W Moore, "Indications and surgical technique for repair of extracranial occlusive lesions," in Vascular Surgery, vol 1, fourth ed, R B Rutherford, ed (Philadelphia: W B Saunders Co, 1995) 1554-1573.

(36.) Ibid.

(37.) Ibid.

(39.) Ibid; D M Shah et al, "Carotid endarterectomy by eversion technique: Its safety and durability," Annals of Surgery 228 (October 1998) 471-478.

(40.) Moore, "Indications and surgical technique for repair of extracranial occlusive lesions," 1554-1573.

(41.) Biller et al, "Guidelines for carotid endarterectomy: A statement for healthcare professionals from a special writing group of the stroke council."

(42.) B A Perler, "The impact of advanced age on the results of carotid endarterectomy: An outcome analysis," Journal of the American College of Surgeons 183 (December 1996) 559-564.

(43.) A J Evans, J A Evans, "Advances in stroke therapy: Introduction to cerebral angioplasty and cerebral thrombolysis," Journal of the Florida Medical Association 84 (April/May 1997) 235-238; Yao, "Angioplasty and stenting for carotid lesions: An argument against," 245-254.

(44.) Bandyk, "Carotid endarterectomy: The `gold standard" for prevention of stroke from severe carotid stenosis," 232-234; Yao, "Angioplasty and stenting for carotid lesions: An argument against," 245-254.

Home Study Programs Available for CRNFA Recertification

The Certification Board Perioperative Nursing (CBPN) often is asked for clarification about using AORN Home Study Programs for certified RN first assistant (CRNFA) recertification. In response to this, the CBPN has made available an extensive list of RNFA-specific subject matter, along with other important information that should be used as a guide when determining appropriate programs for CRNFA recertification. This information is available online at http://www.certboard.org, on the CRNFA recertification application, or by calling CBPN at (888) 257-2667. A sample of these subject areas include

* scope of practice;

* nursing process for RNFAs;

* asepsis, infection control, and epidemiology;

* surgical anatomy and physiology and pathophysiology;

* intraoperative RNFA nursing behaviors;

* invasive and noninvasive diagnostic procedures and surgical complications;

* assisting considerations and procedure management;

* surgical hazard recognition and intervention;

* communication skills and professional development;

* preoperative and postoperative patient care and discharge planning;

* trauma and physical assessment;

* pharmacology;

* medical record dictation;

* legal, policy, and practice issues;

* home health care related to RNFA practice;

* technology changes and advances;

* health care reform; and

* managed care.

Take advantage of the Journal as your contact hour resource to meet the requirements for recertification. Almost all of the Home Study Programs meet the criteria. The Journal specifies whether each month's Home Study Programs meet either or both CRNFA or CNOR recertification criteria.

Examination

CAROTID ARTERY STENOSIS AND ENDARTERECTOMY

1. Carotid artery stenosis is characterized by progressive narrowing of the carotid vessels and

a. plaquing, seventh nerve paralysis, and demyelination.

b. ulcerations, bradykinesia, and demyelination.

c. atherosclerotic changes, seventh nerve paralysis, and bradykinesia.

d. atherosclerotic changes, plaquing, and ulceration.

2. The area where the common carotid vessel branches into the internal and external carotid arteries also is known as the

a. subclavian bifurcation.

b. jugular bifurcation.

c. subclavian bulb.

d. carotid bulb.

3. The mechanisms of acute arterial occlusion and embolization resulting from carotid artery stenosis are significant health care issues because

a. cerebral aneurysm is the second most common cause of death after heart attack.

b. cerebral palsy is the most debilitating neurological disease process after heart attack.

c. stroke is the third most common cause of death in the United States.

d. myocardial infarction leads to stroke in 38% of patients age 70 or older.

4. Cerebral blood flow is provided by

a. portal circulation.

b. collateral cardiac vessels.

c. the internal carotid and vertebral arteries.

d. the internal carotid and subclavian arteries.

5. Collateral blood flow through the allows the body to compensate for reduced blood flow from any of the major contributing blood vessels.

a. Palmar Arch

b. Circle of Willis

c. Phrenulum Lingua

d. Optic Chiasma

6. Factors that regulate cerebral blood flow are

a. blood pressure, metabolic demands, and the partial pressures of carbon dioxide (C[O.sub.2]) and oxygen.

b. metabolic demands, sympathetic stimulation, and heart rate.

c. partial pressure of C[O.sub.2], heart rate, and optic nerve stimulation.

d. partial pressure of oxygen, sympathetic stimulation, and optic nerve stimulation.

7. The -- facilitates blood pressure and heart rate changes.

a. moro response

b. baroreceptor reflex

c. Perez reflex

d. Babinski response

8. All of the following are symptoms of a transient ischemic attack (TIA) except

a. lower extremity claudicating pain.

b. minimal loss of sensation in one hand.

c. complete hemiparesis on the contralateral side of the carotid lesion.

d. temporary blindness on the ipsilateral side of the carotid lesion.

9. A -- is indicative of turbulent blood flow through a diseased artery.

a. rhonchus

b. bronchophony

c. gallop

d. bruit

10. The following diagnostic tools are specific to carotid artery stenosis:

a. contrast arteriography, electromyography, and echoencephalography.

b. duplex ultrasound, electromyography, and computed tomography (CT) scan.

c. duplex ultrasound study, contrast arteriography, and magnetic resonance arteriography.

d. magnetic resonance imaging, echoencephalography, and CT scan.

11. Potential cardiogenic causes of ischemic strokes or TIAs include

a. atrial fibrillation, atrial flutter, mitral valve prolapse (MVP), and patent foramen ovale.

b. atrial flutter, arterial dissection, intracranial artery stenosis, and fibromuscular dysplasia.

c. fibromuscular dysplasia, sickle cell disease, MVP, and hypercoagulation states.

d. patent foramen ovale, arterial dissection, hypercoagulation states, and sickle cell disease.

12. -- may be a good determinant of cavitated, gelatinous, "soft" atheroma.

a. Contrast arteriography

b. Carotid duplex ultrasound

c. Magnetic resonance imaging

d. Computed tomography

13.All of the following are complications of contrast arteriography except

a. arterial dissection.

b. pesudoaneurysm formation.

c. infection.

d. implant migration.

14. Magnetic resonance angiography may not be an option for patients who

a. have implanted metallic devices, may be unable to lie still, or are claustrophobic.

b. may be unable to lie still, have renal insufficiency, or have hepatic disease.

c. have implanted metallic devices, are allergic to contrast media, or have hepatic disease.

d. are claustrophobic, have renal insufficiency, or are allergic to contrast media.

15. Medical treatment for carotid artery stenosis includes all of the following except

a. weight reduction.

b. antihypertensive therapy.

c. limiting alcohol consumption.

d. antiplatelet therapy.

16. Carotid artery endarterectomy is beneficial for symptomatic patients with a recent nondisabling neurological event and ipsilateral stenosis of

a. 10% to 30%.

b. 30% to 50%.

c. 50% to 70%.

d. 70% to 90%.

17. Surgical risk data used to develop patient selection criteria are based on

a. age, blood pressure, smoking, coronary disease, diabetes, and hyperlipidemia.

b. blood pressure, diabetes, hepatic disease, renal insufficiency, neurological deficit, and pulmonary disease.

c. age, coronary disease, renal insufficiency, alcohol consumption, neurological deficit, and ethnicity.

d. smoking cessation, hyperlipidemia, hepatic disease, alcohol consumption, ethnicity, and pulmonary disease.

18. The recommended combined perioperative neurological morbidity and mortality rates for symptomatic patients with TIAs is

a. 3%.

b. 5%.

c. 7%.

d. 9%.

19. Some studies strongly indicate that early revascularization

a. rapidly occludes in spite of postoperative medication therapy.

b. increases the patient's chance for restenosis.

c. precipitates hemorrhage in the infarcted area.

d. precipitates development of intracranial lesions.

20. Before 1953, the following procedures were used to treat carotid artery stenosis:

a. cervical sympathectomy, carotid arteriovenous fistula, carotid vein stripping, and carotid artery resection.

b. thrombectomy of occluded carotid arteries, carotid vein stripping, carotid/jugular bypass, and stellate ganglion block.

c. carotid bifurcation ligation, carotid arteriovenous fistula, carotid/jugular bypass, and carotid artery resection.

d. stellate ganglion block, cervical sympathectomy, thrombectomy of occluded carotid arteries, and carotid bifurcation ligation.

21. A cardiac evaluation is particularly important in this patient population (ie, people with carotid artery stenosis) because

a. of the frequency of comorbid neurological disease.

b. a preexisting neurological deficit precludes accurate responses to health questionnaires.

c. a preexisting renal insufficiency increases the patient's risk of complications.

d. of the frequency of comorbid cardiac disease.

22. Postoperative teaching performed preoperatively includes

a. respiratory care, progression of diet and activity, and frequency of vital signs and neurological checks.

b. progression of diet and activity, preoperative bowel preparation, and the potential for speech therapy to treat aphasia, if needed.

c. respiratory care, eye care for ipsilateral lid droop, and preoperative bowel preparation.

d. frequency of vital signs and neurological checks, eye care for ipsilateral lid droop, and the potential for speech therapy to treat aphasia, if needed.

23. The nurse instructs the patient to take all preoperatively prescribed medications before admission except for

a. aspirin and aspirin-containing products, antihypertensive medications, and antidysrhythmics.

b. antiplatelet medications, antihypertensive medications, and neuromuscular blocking agents.

c. warfarin sodium, aspirin and aspirin-containing products, antiplatelet medications, and diabetic medications.

d. diabetic medications, all facial medicated creams and lotions, and antidysrhythmics.

24. All of the following are advantages to local or cervical block anesthesia except that the

a. surgeon can evaluate the patient's mental status.

b. anesthesia care provider can use halogenated anesthetic agents.

c. patient's motor status can be evaluated ensuring adequate cerebral circulation.

d. surgeon can evaluate cerebral tolerance to clamping of the carotid vessels.

25. Halogenated anesthetic agents have been shown to increase cerebral blood flow and decrease cerebral metabolism allowing

a. anesthesia to be provided to a specific region of the body.

b. the surgeon to evaluate the patient's motor status.

c. the patient to independently maintain a patent airway and respond to verbal commands.

d. improved tolerance of carotid clamping.

26. Cerebral perfusion may be monitored during carotid endarterectomy with intraoperative

a. electroencephalography (EEG) and cerebral oximetry.

b. cerebral oximetry and continuous CT scans.

c. EEG and pneumoencephalography.

d. continuous CT scans and echoencephalography.

27. Extreme hyperextension of the neck during positioning should be avoided because it may

a. stimulate arthritic symptoms postoperatively and adversely affect the recovery process.

b. increase venous pressure and stimulate incisional bleeding.

c. actually impede exposure by tightening the stemocleidomastoid muscle and limit mobility of the common carotid artery and the bifurcation.

d. cause fragmentation of the atheromatous lesions and subsequent embolization and stroke.

28. The advantage of a vertical incision is that it

a. is more acceptable cosmetically.

b. produces less local nerve damage.

c. can be extended distally and proximally to provide additional exposure, if needed.

d. heals more rapidly and provides greater postoperative muscular support.

29. The -- is a landmark for the carotid bifurcation where it obliquely crosses the carotid to the internal jugular vein.

a. common facial vein

b. retromandibular vein

c. superior sagittal vein

d. transverse sinus vein

30. Injury to the hypoglossal nerve, which passes across the internal and external carotid arteries, causes

a. bradycardia and subsequent hypotension.

b. lateral deviation of the tongue toward the surgical side during protrusion and difficulty swallowing.

c. droopy eyelid on the contralateral side.

d. difficulty swallowing and speech impairment.

31. When dissecting the carotid bifurcation, the surgeon may inject the tissues of the carotid body and sinus with 1% lidocaine to

a. provide vasoconstriction, which minimizes intraoperative bleeding.

b. mobilize tissue layers, facilitating dissection and cross clamping.

c. slow the rate of absorption, providing a longer duration of postoperative pain relief.

d. prevent a reflex vagal response, resulting in bradycardia and subsequent hypotension.

32. A shunt may be used intraoperatively for all of the following reasons except

a. EEG and cerebral oximetry changes indicating cerebral hypoxia.

b. hypotension resulting in sensorium changes and facial numbness.

c. low pressures in the clamped distal internal carotid artery.

d. poor back bleeding from an unclamped internal carotid artery.

33. Complications of using a shunt include

a. air or thrombotic emboli, decreased peripheral circulation, and intimal damage.

b. intimal damage and excessively rapid blood flow resulting in overprofusion.

c. intimal damage, air or thrombotic emboli, and decreased access to the vessel.

d. decreased access to the vessel and excessively rapid blood flow, which results in overprofusion.

34. A vein or prosthetic patch may be used to

a. keep the internal and external carotid in close proximity.

b. increase the diameter of the vessel.

c. control blood flow later in the procedure.

d. radiologically identify the carotid vessels post-operatively.

35. -- may be used at the end of the procedure to reverse anticoagulation.

a. Warfarin sodium

b. Protamine sulfate

c. Anistreplase

d. Papaverine hydrochloride

36. Bleeding postoperatively can cause

a. hematomas resulting in tracheal deviation and respiratory distress.

b. decreased cerebral circulation resulting in transient ischemic attacks and stroke.

c. coagulapathies and blood pressure abnormalities.

d. decreased tissue perfusion and poor wound healing.

37. The intraoperative role of the RN first assistant includes all of the following except

a. positioning, prepping, and draping.

b. exposing the surgical site.

c. retracting and providing hemostasis.

d. injecting the carotid body and sinus with lidocaine.

38. To ensure cardiovascular and neurological stability, patients now are spending an extended time in the postanesthesia care unit rather than an intensive care stay.

a. true

b. false

30. Discharge instructions include all of the following except

a. performing wound care.

b. resuming preoperative medications.

c. continuing on a diet of soft solids for two weeks to minimize stress on the incision.

d. setting up a postoperative follow-up appointment in two weeks.

40. Severe hypertension should be avoided postoperatively because

a. residual plaque may break away and cause a stroke.

b. it causes subcutaneous swelling, which delays healing.

c. residual plaque may break away and cause a heart attack.

d. it can cause stress on the suture line and lead to postoperative bleeding.

AORN, Association of periOperotive Registered Nurses, is accredited os o provider of continuing education in nursing by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. AORN recognizes this activity as continuing education for registered nurses. This recognition does not imply that AORN or the ANCC's Commission on Accreditation approves or endorses any product included in the activity. AORN maintains the following state board of nursing provider numbers: Alabama ABNP0075, California CEP13019, and Florida FBN 2296. Chock with your state board of nursing for acceptability of education activity for relicensure.

Professional nurses ore invited to submit manuscripts for the Home Study Program. Manuscripts or queries should be sent to Editor, AORN Journal, 2170 S Parker Rd, Suite 300, Denver, CO 80231-5711. As with all manuscripts sent to the Journal, papers submitted for Home Study Programs should not hove been previously published or submitted simultaneously to any other publication.

Answer Sheet

[ILLUSTRATION OMITTED]

Learner Evaluation

CAROTID ARTERY STENOSIS AND ENDARTERECTOMY

The following evaluation is used to determine the extent to which this Home Study Program met your learning needs. Rate the following items on a scale of 1 to 5.

[ILLUSTRATION OMITTED]

OBJECTIVES

To what extent were the following objectives of this Home Study Program achieved?

(1) Define the physiology of cerebral circulation.

(2) Discuss the pathophysiology of impaired cerebral circulation.

(3) Identify the selection criteria for the treatment options available to patients with carotid artery stenosis.

(4) Describe the preoperative process of patients undergoing carotid artery endarterectomy.

(5) Discuss perioperative nursing care of patients undergoing carotid endarterectomy for carotid artery stenosis.

(6) Describe the postoperative course of patients undergoing carotid endarterectomy.

PURPOSE/GOAL

To educate the perioperative nurse about carotid artery stenosis and treatment with carotid artery endarterectomy.

CONTENT

(7) Did this article increase your knowledge of the subject matter?

(8) Was the content clear and organized?

(9) Did this article facilitate learning?

(10) Were your individual objectives met?

(11) How well did the objectives relate to the overall purpose/goal?

TEST QUESTIONS/ANSWERS

(11) Were they reflective of the content?

(12) Were they easy to understand?

(13) Did they address important points?

What other topics would you like to see addressed in a future Home Study Program? Would you be interested or do you know someone who would be interested in writing an article on this topic?

Topic(s): --

Author names and addresses: --

JoAnn Basso Cundy, RN, BSN, CNOR, CRNFA, is the certified RN first assistant for cardiothoracic surgical services, Watson Clinic, Lakeland, Fla.

COPYRIGHT 2002 Association of Operating Room Nurses, Inc.
COPYRIGHT 2002 Gale Group