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Current status in cervical carotid artery stent placement
Seminars in Cerebrovascular Medicine and Stroke Vol. 2 No. 4 2002
Current Status in Cervical Carotid Artery Stent Placement MICHAEL H. WHOLEY, BOULUS TOURSARKISSIAN, HECTOR FERRAL San Antonio, Texas
ABSTRACT
Carotid artery stenting has become a recommended alternative to carotid endarterectomy at many clinical centers in this country and aboard. Results of randomized clinical trials that established the efficacy of carotid endarterectomy are described and compared with retrospective analyses of results from investigative groups in this country and aboard. Introduction of cerebral protection devices appears to have decreased the 30-day stroke and death rate. These data suggest comparability with the results of carotid endarterectomy and support the value of currently on-going trials and registries. Increasing use of carotid artery stenting is predicted. Key words: carotid artery stenting, carotid endarterectomy, cerebral protection device.
As a result of important landmark studies such as the North American Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Atherosclerotic Study (ACAS), surgical intervention was found to be beneficial in decreasing the relative risk of morbidity and mortality in patients with significant carotid artery atherosclerotic disease. 1-4 However, carotid endarterectomy still carries significant perioperative risk. The risk of perioperative stroke from carotid endarterectomy varies from 1.5% to 9% depending on the published series. 5'6 The perioperative stroke and death rate was 7.5% in the European Carotid Surgery Trial (ECST), 5.8% in NASCET, and 2.3% in A C A S . 1-4'7"8 Also, the N A S C E T perioperative stroke and death rate for contralateral occlusions was 14.3%. 9 The risk of cranial nerve palsies occurs in 7.6% to 27% cases, and these results frequently are not recorded as morbidity in surgical publications. 5,s'l~
As an alternative to the traditional surgical treatment of carotid artery occlusive disease, there has been much interest in the use of carotid artery stent placement. 7'8'~~ Very few other new specialties have faced as much political and overall scrutiny as has carotid stenting. This article presents the current status of the new field of carotid stenting including historical developments, techniques, technical successes, complications rates, and follow up.
Development Of Carotid Stenting Mathias,~ 2 Theron, I3 and Kache114 pioneered treatment of cervical carotid artery disease in the 1980s. With the advent of stent technology, interventional management of carotid artery disease began to develop as a practical new technique as shown in early work by Diethrich, 7 Roubin, s and Wholey. j5 Stents provide key improvements compared with angioplasty alone. They also help to decrease restenosis, to prevent disastrous dissections, and to contain lesion surfaces susceptible for thromboemboli. When the use of stenting was pioneered (from 1995 to 1999), especially in the United States, only 2 peripheral stent systems were primarily available: the balloonmounted Palmaz stent (Cordis Johnson and Johnson,
From the Departments of Cardiovascular and Interventional Radiology and Vascular Surgery, University of Texas Health Science Center at San Antonio, San Antonio, TX. Address reprint requests to Michael H. Wholey, MBA, MD, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr, San Antonio, TX 78284. Email: [email protected]. Copyright 2002, Elsevier Science (USA). All rights reserved. 1528-9931/02/0204-0005535.00/0 doi: 10.1053/scds.2002.130316
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Carotid Artery Stent Placement 9 Wholey et al Warren, NJ) and the Wallstent (Schnieder, Boston Scientific, Natick, MA). According to the 1997 world carotid registry, of approximately 2,041 stents placed, Palmaz stents were used in 1,110 cases (54%) followed by Wallstents in 840 cases (40%). 11 Both systems have advantages and disadvantages. The Palmaz was of shorter length, required only a 2-step process (predilation and deployment), and had more precise deployment, which allowed it to be placed at the ostium of the internal carotid artery as opposed to the Wallstent, which was frequently placed across the origin, extending into the common carotid artery. However, the major disadvantage of the Palmaz, like other balloon-expandable stents, was the compression and deformability issue. In our series and others, compression and deformability was a rare occurrence (less than 2% per year); however, stent compression was a real threat and could not be toleratedJ ~.15 Other centers have experienced higher deformity rates. Mathur et a116 reported Palmaz stent collapse in 11 of 70 patients who came for 6-month follow-up angiographic examinations. When nitinol stents became available in 1999 in the United States, many surgeons had changed or were in the process of changing from balloon-mounted stents to either Wallstents or the newer nitinol stents. In the updated 2000 world registry, of 5,427 stents placed, Wallstents were placed in 3,144 cases (57%) and Palmaz in 1,826 cases (33%). 17
Development Of Carotid Cerebral Protection Unlike angioplasty and stent placement of peripheral arteries, the brain is an unforgiving end organ. Dislodge-
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ment of embolic particles during catheter manipulation and stent placement can result in disastrous consequences. Dislodgment is a sporadic event; both symptomatic and asymptomatic patients can suffer the occurrence. Embolic is also been a sporadic event. The most common route for particles dislodged during stent placement has been the middle cerebral artery and frequently on to the posterior parietal artery. Various cerebral protection devices--including various filters and balloon catheter systems--have been developed to prevent dislodgment of embolic particles. These devices trap, collect, and remove particles distal to the lesion. Yet, the devices must be of low profile so they do not increase the risk of dislodging particles as well as simple and quick to deploy so they do not lengthen procedure time or damage the vessel distal to the lesion. Currently, 3 types of cerebral protective devices are used. The first type is a microcatheter, such as the PercuSurge Guardwire (Medtronics, Minneapolis, MN), that has a soft, occlusive balloon catheter at or near the distal tip (Fig 1.) This distal tip is inflated during the procedure. The second type is a microcatheter or wire with a filter designed to capture and retrieve embolic particles. Several companies manufacture this type of device. The third type, manufactured by ArteriA (Menlo Park, CA), relies on an occluding guiding catheter and occluding balloon in the external carotid artery, which allows for reverse arterial flow from the targeted internal carotid artery into the guide catheter and then via the femoral vein through a special sheath system (Fig 2.) The balloon catheter system was initially developed and employed by Theron et a112'18 in 1990. They used a triple-coaxial system with a guiding catheter and a microcatheter with the distal latex balloon catheter. The microcatheter is carefully advanced past the carotid
Fig. 1. The PercuSurge (Medtronics, Minneapolis, MN) occluding balloon protection system.
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Fig. 2. The ArteriaA (Menlo Park, CA) reverse flow protection system.
lesion and inflated during the procedure. The angioplasty balloon catheter is advanced over the microcatheter and through the guiding catheter. With the microcatheter inflated, embolic debris is aspirated through the guiding catheter. Modifications of the general concept have been made to the Theron technique with the PercuSurge, ie, a small, elastomeric balloon catheter is inserted on a distal 0.014-inch to 0.018-inch guide wire. The second type of neurological protection device is the microfilter. The filter is designed to be advanced past the lesion in a closed state and then opened during the procedure to collect embolic debris. After the procedure is completed, the filter collapses, and the particles are removed from the body. Gott et a119 developed an early vascular filter in 1968 for application during coronary bypass procedures. One of the earliest developments for a carotid filter-like system was by Wholey et al in 1988. 20 Several new companies have developed embolic filter designs based on the general principle stated above. In addition, the filter may be used on a guide wire design to allow balloon catheters and stents to be advanced coaxially along the filter wire. The various companies with filters in different stages of development include the following: 9 Angioguard (recently acquired by Cordis Johnson & Johnson, Warrenton, NJ; Fig 3) 9 Embolic Protection, Inc (recently acquired by Boston Scientific, Natick, MA; Fig 4)
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Fig. 3. The Cordis Johnson & Johnson (Warrenton, NJ) (formerly AngioGuard) microfilter protection system.
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Fig. 4. The Boston Scientific (Natick, MA) (formerly Embolic Protection, Inc) microfilter protection system demonstrating an off-center lasso-type microfilter.
oMednova (recently acquired by Abbott, Abbott Park, IL; Fig 5) oACS Guidant Accunet (Santa Clara, CA; Fig 6) oMetamorphic Surgical (Pittsburgh, PA) oIntraTherapeutics (Minneapolis, MN) Which device is better suited for cerebral protection: the occlusive balloon catheter or the microfilter? Both systems must be of low-enough profile to be advanced past high-grade lesions while still functioning as a highly torquable guide wire. The use of a secondary guide wire for support across tight lesions, ie, a "buddy wire," as well as the need for predilation before filter passage is attempted, must be eliminated.
Both protection devices have advantages and disadvantages. The advantages of the balloon catheter system, such as the PercuSurge, include (1) the existence of clinical studies in both neurological and coronary systems, (2) the use of soft latex and other materials that minimally damage the artery, and (3) a high rate of removal of embolic debris.Disadvantages of the balloon system include (1) occlusion of the entire flow during all or a majority of the procedure in patients who frequently have compromised contralateral carotid artery and Circle of Willis and (2) inability to evaluate the lesion fluoroscopically while the balloon is inflated in the internal carotid artery. Advantages of an embolic filter device include (1) the ability to provide flow during the procedure while fully
Fig. 5. The Abbott (Abbott Park, IL) (formerly Mednova) microfilter protection system.
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Fig. 6. The ACS (Santa Clara, CA) Guidant Accunet microfilter protection system.
expanded and (2) that is does not require flushing. Disadvantages of the umbrella-type microfilter technique include (1) the induction of spasm or damage to the vessel wall by strong struts; (2) the risk of releasing micro particles (ie, particles < 100 [am in size); and (3) the possibility of trapped embolic particles being squeezed out the filter as it is retracted and collapsed.
Carotid Stent TechniqueWith Cerebral Protection Carotid stenting can be divided into to several steps. Regardless of whether cerebral protection is used, all patients are pretreated with aspirin (325 mg daily) and clopidogrel bisulfate (75 mg orally daily) for 3 to 5 days before the procedure. Pretreatment imaging includes a complete diagnostic angiogram including a left anterior oblique view of the aortic arch, selective carotid views of the cervical and intracerebral arteries, and a view of the vertebral arteries with attention to the circle of Willis. Additionally, cerebral computed tomography scans with contrast are obtained(Figs 7A through H). Standard retrograde access is obtained in ithe common femoral artery for all cases. Approximately 5,000 U heparin is administered to maintain ACT levels between 250 and 300. With the use of filters, it is imperative to maintain adequate heparinization. Using a 5-Fr catheter and steerable 0.035-inch guide wire, the common carotid artery is selected. Under road map images, the external carotid artery is selected whenever possible to allow for the exchange of a stiff 0.035-inch guide wire into one of the external carotid artery branches. This stiff wire serves as an anchor for advancement of an 8-Fr guiding catheter or a 6- to 7-Fr long vascular sheath into the common carotid artery approximately 2 cm caudal to the carotid bifurcation.
Under road map images, the embolic protective system is advanced past the lesion, and the filter or embolic protective balloon is deployed in the cervical or petrous portion of the internal carotid artery. For cases involving the carotid bulb, 1.0 mg atropine is administered intravenously. Over the filter or protective balloon, a 3.5- to 4.0-ram PTCA balloon catheter is advanced to predilate the lesion. Predilation helps advance the approaching stent delivery system, allowing for smoother stent placement, and provides a final check of vessel and lesion dimensions. Next, the self-expandable stent is advanced and placed into position relative to the lesion. The stent size is chosen depending on lesion and vessel characteristics. If possible, we avoid crossing into the bifurcation, but because of the less-precise nature of self-expandable stents, we frequently cross into the common carotid artery; this requires a slightly longer stent. We choose a stent approximately 1 mm larger than the diameter of the largest vessel stented. For the common carotid artery, the stent size is normally 8 to 10 m m in diameter. Tapered stents have recently become available and have been employed. With necessary injections of contrast to ensure positioning, we then deploy the stent. Afterwards, we perform angioplasty on a majority (80%) of lesions with either a 5-, 5.5-, or 6.0-mm balloon catheter. Poststent angiograms of the lesion and intracerebral angiograms are then obtained. After the procedure, patients are maintained on a regimen of 81 mg aspirin and 75 mg clopidogrel every day for 1 month.
Results Of Carotid Stenting and Cerebral Protection Since the beginning of its use, carotid stenting has had high technical success of 98% to 99% regardless of the initial use of peripheral and coronary guide wires,
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Fig. 7. (A) Initial angiogram of the thoracic aorta of a symptomatic 83-year-old man showed patent origin of great vessels and minimal tortuosity of the innominate and right common carotid arteries. (B) Visualization of a selected right common carotid artery with a 5-Fr catheter showed a high-grade (80%) lesion in the proximal internal carotid artery. (C) Under road map images, the external carotid was selected with a torquable 0.035-inch guide wire to allow advancement of 5-Fr catheter and subsequent exchange to a 0.035-inch Amplatz super-stiff guide wire. continued
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Fig. 7 continued. (D) After advancing a 7-Fr, 90-cm vascular sheath into the common carotid approximately 2 to 3 cm caudal to the bifurcation, the PercuSurge Guardwire (Medtronics, Minneapolis, MN) was carefully advanced under road map images past the lesion near the level of the petrous carotid artery. (E) The PercuSurge Guardwire balloon was inflated to ensure occlusion of the vessel, and the internal carotid lesion was predilated with a 3.5 x 2-cm percutaneous transluminal coronary angioplasty balloon catheter. (F) The Precise 6 x 30-ram stent was positioned under road map images and deployed. Next, postdilation with a 5.0 mm x 2 cm-compatible balloon catheter (0.014 inch) was performed (not shown). With the PercuSurge Guardwire balloon still inflated, a 5-Fr aspiration catheter was advanced over it, past the stent, to th~ level of the balloon catheter where blood and embolic debris was aspirated (not shown). (G) After deflation, postintervention angiograms were performed of the carotid stent. (H) Poststent angiogram (anteroposterior view) of the intracerebral arteries compared with preintervention angiogram. Anterior cerebral arterial flow was present but not seen on the preintervention angiogram.
Carotid Artery Stent Placement 9 balloons, and stents, el The rate of complications, based on minor and major strokes and procedure-related deaths, has decreased from 5.7% to 4.3% based on the results of 8,612 carotid artery stenting procedures as published in the w o r l d registry, u'21'22 With regard to non-procedure-related deaths, the total stroke and death rate has increased to 5.20%. 21 This is slightly higher than the rates reported by the major centers and takes into account the learning curve from smaller centers. During a 5-year study period, the 30-day minor stroke rate improved from 7.1% (n = 7) for the first year to 3.1% (n = 5) for the fifth year in Roubin et al's study of 528 patients, z3 Wholey et al,24 at PittsburghVascular Institute (PVI), reported a total minor and major stroke and neurological-related death rate of 3.9% (n = 20) for 513 patients treated. With the advent of embolic protection, complications associated with carotid stenting have decrease. At PVI, Wholey et a124 reviewed immediate complications with and without embolic protection and found fewer strokes and neurological-related deaths: 2.4% with protection versus 4.2% without protection. This occurred despite a relatively high rate of technical failures. Others have reported similar improvements in neurological events with cerebral protection. Reimers et a125 reported a stroke and death rate of 1.2% in 86 patients with cerebral protection; A1-Mubarek et a126 reported a 2% stroke and death rate for 162 patients in a multicenter study; and Henry et a127 reported a stroke and death rate of 2.7% for 167 patients. In our long-term follow-up of patients who had received carotid artery stents, we found the rate of ipsilateral minor and major strokes and neurologicalrelated death-free rates to be low. We reported a 3-year freedom rate from all fatal and iPsilateral nonfatal strokes, not including the 30-day periprocedural period, of 94.1% and a 5-year rate of 93.1% using the Palmaz stent. 24 Others have reported similar numbers. In a follow-up of 528 patients, Roubin et al23 performed Kaplan-Meier analysis, which revealed that the 3-year freedom rate from all fatal and ipsilateral nonfatal strokes--with and without the inclusion Of the 30-day periprocedural period--was 92_+1% and 99+_1%, respectively, Paniagua et a128 followed up 62 patients for a mean of 17 months and noted that 2.8% of patients (n = 2) suffered ipsilateral neurological events after coronary artery stenting. In long-term f011ow-up of vessel patency, there were good overall rates: for the 496 patients in the PVI study, the 3-year patency rate for the combined stent types was 91.4% using "fairly strict ultrasound c r i t e r i a . 24 Others have reported similar figures in a limited number of publications. Paniagua et al28 reported 94.3% patency in their-4ong-term follow up (mean, 17 months) of 62 patients. Dietz et a129 reported 98.5% patency in long-
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term follow-up (mean, 20 months) of 43 patients. On the contrary, Leger et al 3~ showed significant to critical recurrent stenosis in 75% of patients (n = 6 of 8) in a 20-month follow up study.
Status Of Clinical Trials Unlike with PTCA, renal, or innominate artery stenting, the Federal Drug Administration (FDA) has required that randomized trials and registries be performed to assess the safety of carotid stenting. The end points for the carotid tilter are major neurological events such as minor and major strokes and deaths. Currently, 2 randomized trials are underway in the United States. The Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) is a randomized carotid stent placement-versus-surgical endarterectomy trial that has been recently approved by the FDA. It is being initiated currently and will eventually comprise approximately 40 centers and 2,300 patients with symptomatic carotid stenoses. The stent to be used is the ACS (Santa Clara) Guidant Acculink with Accunet Filter. The second randomized trial is SAPPHIRE, which is studying stent placement versus surgical endarterectomy in high surgical-risk patients with symptomatic lesions (Tables 1 and 2). The SAPPHIRE trial uses the Cordis Precise Stent and Angioguard Filter and will comprise approximately 30 centers and 600 patients in each arm of the study. Various registries exist, most of which comprise high surgical-risk patients (Table 3). These registries include Archer, BEACH, Security, Caress, Cabernet, and Shelter. European studies include SPACE, a German trial, and EVA I!, a French study.
Conclusion Within the past 5 years, carotid stent placement has evolved as an alternative treatment for extracranial carotid artery disease. 7"a'12-1a The high technical success of the procedure, as well as its relatively low complication rate, makes carotid stenting a substitute for carotid endarterectomy for symptomatic patients, especially those with high-risk medical comorbidities. Although it is difficult to compare endarterectomy with endovascular stent placement, especially regarding generally higherrisk patients in the latter group, some early comparisons can be made. The rate of neurological complications and deaths associated with endovascular stent placement, with and without cerebral protection, in symptomatic patients is 5.36%, which is acceptable for a newly developed procedure. 22 This rate generally falls within the 6% to 7% perioperative stroke and death rate established by the AHA for symptomatic patients under-
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Table 1. High-Risk Classification Used in the SAPPHIRE, BEACH, and Security Trials
Table 2. Exclusion Criteria for Carotid Stenting Patient is experiencing an acute ischemic neurologic stroke or has experienced a stroke within the past 48 h Patient has an intracranial mass lesion (ie, abscess, arteriovenous malformation, tumor, or infection) Intraluminal thrombus Total occlusion of the target carotid artery treatment site Patient has any intracranial aneurysm (>9 mm) Previous life-threatening contrast reaction Patient is at high risk for nephrotoxicity from contrast secondary to underlying renal disease and is not yet on dialysis Patient has an uncorrected bleeding disorder Lesions not technically feasible via a percutaueous approach Patient or his or her legal representatives are unable to give informed consent Patient has long multiple lesions or complex lesions with ulcerative and/or active thrombotic changes at the carotid bifurcation as diagnosed by previous angiograms
Significant medical comorbidities CHF: III/IV LVF: <30% OHS within 6 weeks Recent MI 24 h to 30 d Unstable angina; CCS HI/IV Concurrent requirement for coronary revascularization Abnormal stress test? Severe pulmonary disease Chronic oxygen therapy Resting Po2 s 60 mm Hg Baseline hematocrit s 50% of normal FEV1 or DLCO s 50% of normal Age > 80 y Significant anatomical abnormalities Contralateral carotid occlusion Contralateral laryngeal palsy Previous radiation to head and/or neck Previous CEA recurrent stenosis Surgically difficult-to-access high cervical lesions (high cervical lesions or CCA lesions below the clavicle Severe tandem lesions Laryngectomy or tracheostomy Inability to extend head from arthritis or other Hostile neck Abbreviations: SAPPHIRE; BEACH; SECURITY; CHF, congestive heart failure; LVF, left ventricular function; OHS, open heart surgery; MI, myocardial infarction; CCS, chronic compartment syndrome; P% partial pressure of oxygen; FEV~, forced expiratory volume in 1 second; DLCO, single-breath diffusing capacity; CEA, carotid endarterectomy; CCA, common carotid artery.
g o i n g endarterectomy. 31 The rate of c o m p l i c a t i o n s incurred in stenting a s y m p t o m a t i c patients was r e c o r d e d as 2.91% in the latest survey; this n u m b e r is higher than the accepted 2.3% incurred in the A C A S study. 2-4' 22 W i t h the added safety of carotid e m b o l i c filters and o c c l u s i o n balloons, the rate of c o m p l i c a t i o n s will c o n t i n u e to decrease, especially after the initial learning c u r v e f r o m filters is o v e r c o m e and the next generations o f d e v i c e s are d e v e l o p e d .
E n d 0 v a s c u l a r stent p l a c e m e n t will g r o w in application as t e c h n o l o g i c a l i m p r o v e m e n t s in devices and e q u i p m e n t are d e v e l o p e d and as m o r e training and education o f physicians and patients occurs. T h e use o f carotid stenting is currently g r o w i n g b e t w e e n 20% and 4 0 % per year despite political and e c o n o m i c difficulties. B y the end o f the decade, the n u m b e r o f stenting procedures should equal the n u m b e r o f carotid endarterectomies performed. As the design and applicability o f stents, guide catheters, and cerebral protection d e v i c e s are i m p r o v e d , the technical success, patency, and c o m p l i c a t i o n rates will improve. Still, the important test for carotid stent placem e n t will be its l o n g - t e r m (1-, 3-, and 5-year) patency as w e l l as the results o f r a n d o m i z e d studies c o m p a r e d with the " g o l d standard" of carotid endarterectomy.
Acknowledgment The author thanks R o s e a n n B o s t at Pittsburgh Vascular Institute and R e n e R o d r i g u e z and Betty R o b l e s at U n i versity of Texas Health S c i e n c e Center at San A n t o n i o
Table 3. Current Clinical Trials and Registreries Trials Sapphire* Crest* Sheltea" Beach Caress EndoTex (Cabernet) Archer Maverick Security Bard *Randomized triall
Device
Distal Protection
5-Fr Precise 6-Fr Acculink 5.5-Fr Wallstent 5.5-Fr Carotid Wallstent 5.5-Fr Wallstent 5-Fr Nexstent 6-Fr Acculink Medtronic-AVE Xact (Abbott) 7-Fr Memotherm
Angioguard-Ex Accunet PercuSurge BSC-EPI PercuSurge BSC-EPI Accunet PercuSurge Mednova Trial stopped
Carotid Artery Stent Placement * for their managerial work; Kathy Hill, RN, Jack Buechtel, RN, and William Mook, nurses and statisticians; and the special team of nurses and technicians at Pittsburgh Vascular Institute and the University of Texas Health Science Center at San Antonio.
References 1. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis: North American Symptomatic Carotid Endarterectomy Trial collaborators. N Engl J Med 325:445-453, 1991 2. Asymptomatic Carotid Atherosclerosis Study Group. Endarterectomy for asymptomatic carotid artery stenosis. JAMA 273:1421-1428, 1995 3. Clinical Advisory: Carotid endarterectomy for patients with asymptomatic internal carotid artery stenosis. J Neurologic Sci 129:76-77, 1995 4. Clinical advisory: Carotid endarterectomy for patients with asymptomatic internal carotid artery stenosis. Stroke 25:2523-2524, 1994 5. Lusby RJ, Wylie EJ: Complications of carotid endarterectomy. Surg Clin North Am 63:1293-1301, 1983 6. Zarins CK: Carotid endarterectomy: The gold standard. J Endovasc Surg 3:10-15, 1996 7. Diethrich EB: Indications for carotid stenting: A preview of the potential derived from early clinical experience. J Endovasc Surg 3:132-139, 1996 8. Yadav JS, Roubin GS, King R et al: Angioplasty and stenting for restenosis after carotid endarterectomy. Stroke 27:2075-2079, 1997 9. Gasecki AP, Elliasziw M, Ferguson GG, et al: Long-term prognosis and effect of endarterectomy in patients with symptomatic severe carotid stenosis and contralateral carotid stenosis or occlusion: Results from NASCET. J Neurosurg 83:778-782, 1995 10. Diethrich EB: Cerebrovascular disease therapy: The past, the present, and the future. J Endovasc Surg 3:7-9, 1996 11. Wholey MH, Wholey M, Bergeron R et al: CUrrent global status of carotid artery stent placement. Cath Cardiovasc Diagn 44:1-6, 1998 12. Theron J, Courtheroux P, Alachkar, et al: New triple coaxial catheter systems for carotid angioplasty with cerebral protection. Am J Neuroradiol 11: 867-874, 1990 13. Mathias KD, Jaeger MJ, Sahl H: Internal carotid stentsPTA: 7 Year exPerience, Cardiovasc Intervent Radiol 20:I-46, 1997 (abstr) 14. Kachel R, Basche St, Heerklotz I, et al: Percutaneous transluminal angioplasty (PTA) of supra-aortic arteries especially the internal carotid artery. Neuroradiology 33:191-194, 1991 15. Wholey MH, Wholey M, Eles G, et al: Endovascular stents for carotid occlusive disease. J Endovasc Surg 4:326-338, 1997
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16. Mathur A, Dorros G, Iyer SS, et al: Palmaz stent compression in patients following carotid artery stenting. Cathet Cardiovasc Diagn 41:137-140, 1997 17. Wholey MH. Wholey M, Mathias K, et al: Global experience in cervical carotid artery stent placement. Cathet Cardiovasc Interv 50:160-167, 2000 18. Theron JG, Payelle GG, Coskun, O, et al: Carotid artery stenosis: Treatment with protected balloon angioplasty and stent placement. Radiology 201:627-636, 1996 19. Fadali AM, Topaz MM, Gott VL: A filtering device for the prevention of particulate embolization during the course of cardiac surgery. Surgery 64:634-639, 1968 20. Wholey MH, Nagurka M, Katz RS: US Patent 4,723,549. Method and apparatus for dilating blood vessels. February 8, 1988 21. Brott T, Adams HE Olinger CP, et al: Measurement of acute cerebral infarction: A clinical examination Scale. Stroke 20:864-870, 1989 22. Wholey MH, Mubarek N, Kracjier Z, et al: Updated Global Carotid Artery Stent Registry (in press). 23. Ronbin GS, New G, Iyer SS, et al: Immediate and late clinical outcomes of carotid artery stenting in patients with symptomatic and asymptomatic carotid artery stenosis: A 5-year prospective analysis. Circulation 103:532537, 2001 24. Wholey MH, Wholey M, Tan WA, et al: Long term follow up comparing balloon-mounted and self-expandable stents (in press). 25. Reimers B, Corvaja N, Moshiri S, et al: A cerebral protection with filter devices during carotid artery stenting. Circulation 104:12-15, 2001 26. A1-Mubarak N, Colombo A, Gaines PA, et al: Multicenter evaluation of carotid stenting with a filter protection system. J Am Coll Cardiol 39:841-846, 2002 27. Henry M, Henry I, Klonaris C, et al: Benefits of cerebral protection during carotid stenting with the PercuSurge GuardWire system: midterm results. J Endovasc Ther 9: 1-13, 2002 28. Paniagua D, Howell M, Strickman N, et al: Outcomes following extracranial carotid artery stenting in high-risk patients. J Invasive Cardiol 13:375-381, 2001 29. Dietz A, Berkefeld J, Theron JG, et al: Endovascular treatment of symptomatic carotid stenosis using stent placement: Long-term follow-up of patients with a balanced surgical risk/benefit ratio. Stroke 32:1855-1859, 2001 30. Leger AR, Neale M, Harris JP: Poor durability of carotid angioplasty and stenting for treatment of recurrent artery stenosis after carotid endarterectomy: An institutional experience. Vasc Surg 33:1008-1014, 2001 31. Moore WS, Barnett HJM, Beebe HG, et al: Guidelines for carotid endarterectomy: a multidisciplinary consensus statement from the ad hoc committee, American Heart Association. Stroke 26:188-200, 1995
Current Status in Cervical Carotid Artery Stent Placement MICHAEL H. WHOLEY, BOULUS TOURSARKISSIAN, HECTOR FERRAL San Antonio, Texas
ABSTRACT
Carotid artery stenting has become a recommended alternative to carotid endarterectomy at many clinical centers in this country and aboard. Results of randomized clinical trials that established the efficacy of carotid endarterectomy are described and compared with retrospective analyses of results from investigative groups in this country and aboard. Introduction of cerebral protection devices appears to have decreased the 30-day stroke and death rate. These data suggest comparability with the results of carotid endarterectomy and support the value of currently on-going trials and registries. Increasing use of carotid artery stenting is predicted. Key words: carotid artery stenting, carotid endarterectomy, cerebral protection device.
As a result of important landmark studies such as the North American Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Atherosclerotic Study (ACAS), surgical intervention was found to be beneficial in decreasing the relative risk of morbidity and mortality in patients with significant carotid artery atherosclerotic disease. 1-4 However, carotid endarterectomy still carries significant perioperative risk. The risk of perioperative stroke from carotid endarterectomy varies from 1.5% to 9% depending on the published series. 5'6 The perioperative stroke and death rate was 7.5% in the European Carotid Surgery Trial (ECST), 5.8% in NASCET, and 2.3% in A C A S . 1-4'7"8 Also, the N A S C E T perioperative stroke and death rate for contralateral occlusions was 14.3%. 9 The risk of cranial nerve palsies occurs in 7.6% to 27% cases, and these results frequently are not recorded as morbidity in surgical publications. 5,s'l~
As an alternative to the traditional surgical treatment of carotid artery occlusive disease, there has been much interest in the use of carotid artery stent placement. 7'8'~~ Very few other new specialties have faced as much political and overall scrutiny as has carotid stenting. This article presents the current status of the new field of carotid stenting including historical developments, techniques, technical successes, complications rates, and follow up.
Development Of Carotid Stenting Mathias,~ 2 Theron, I3 and Kache114 pioneered treatment of cervical carotid artery disease in the 1980s. With the advent of stent technology, interventional management of carotid artery disease began to develop as a practical new technique as shown in early work by Diethrich, 7 Roubin, s and Wholey. j5 Stents provide key improvements compared with angioplasty alone. They also help to decrease restenosis, to prevent disastrous dissections, and to contain lesion surfaces susceptible for thromboemboli. When the use of stenting was pioneered (from 1995 to 1999), especially in the United States, only 2 peripheral stent systems were primarily available: the balloonmounted Palmaz stent (Cordis Johnson and Johnson,
From the Departments of Cardiovascular and Interventional Radiology and Vascular Surgery, University of Texas Health Science Center at San Antonio, San Antonio, TX. Address reprint requests to Michael H. Wholey, MBA, MD, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr, San Antonio, TX 78284. Email: [email protected]. Copyright 2002, Elsevier Science (USA). All rights reserved. 1528-9931/02/0204-0005535.00/0 doi: 10.1053/scds.2002.130316
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Carotid Artery Stent Placement 9 Wholey et al Warren, NJ) and the Wallstent (Schnieder, Boston Scientific, Natick, MA). According to the 1997 world carotid registry, of approximately 2,041 stents placed, Palmaz stents were used in 1,110 cases (54%) followed by Wallstents in 840 cases (40%). 11 Both systems have advantages and disadvantages. The Palmaz was of shorter length, required only a 2-step process (predilation and deployment), and had more precise deployment, which allowed it to be placed at the ostium of the internal carotid artery as opposed to the Wallstent, which was frequently placed across the origin, extending into the common carotid artery. However, the major disadvantage of the Palmaz, like other balloon-expandable stents, was the compression and deformability issue. In our series and others, compression and deformability was a rare occurrence (less than 2% per year); however, stent compression was a real threat and could not be toleratedJ ~.15 Other centers have experienced higher deformity rates. Mathur et a116 reported Palmaz stent collapse in 11 of 70 patients who came for 6-month follow-up angiographic examinations. When nitinol stents became available in 1999 in the United States, many surgeons had changed or were in the process of changing from balloon-mounted stents to either Wallstents or the newer nitinol stents. In the updated 2000 world registry, of 5,427 stents placed, Wallstents were placed in 3,144 cases (57%) and Palmaz in 1,826 cases (33%). 17
Development Of Carotid Cerebral Protection Unlike angioplasty and stent placement of peripheral arteries, the brain is an unforgiving end organ. Dislodge-
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ment of embolic particles during catheter manipulation and stent placement can result in disastrous consequences. Dislodgment is a sporadic event; both symptomatic and asymptomatic patients can suffer the occurrence. Embolic is also been a sporadic event. The most common route for particles dislodged during stent placement has been the middle cerebral artery and frequently on to the posterior parietal artery. Various cerebral protection devices--including various filters and balloon catheter systems--have been developed to prevent dislodgment of embolic particles. These devices trap, collect, and remove particles distal to the lesion. Yet, the devices must be of low profile so they do not increase the risk of dislodging particles as well as simple and quick to deploy so they do not lengthen procedure time or damage the vessel distal to the lesion. Currently, 3 types of cerebral protective devices are used. The first type is a microcatheter, such as the PercuSurge Guardwire (Medtronics, Minneapolis, MN), that has a soft, occlusive balloon catheter at or near the distal tip (Fig 1.) This distal tip is inflated during the procedure. The second type is a microcatheter or wire with a filter designed to capture and retrieve embolic particles. Several companies manufacture this type of device. The third type, manufactured by ArteriA (Menlo Park, CA), relies on an occluding guiding catheter and occluding balloon in the external carotid artery, which allows for reverse arterial flow from the targeted internal carotid artery into the guide catheter and then via the femoral vein through a special sheath system (Fig 2.) The balloon catheter system was initially developed and employed by Theron et a112'18 in 1990. They used a triple-coaxial system with a guiding catheter and a microcatheter with the distal latex balloon catheter. The microcatheter is carefully advanced past the carotid
Fig. 1. The PercuSurge (Medtronics, Minneapolis, MN) occluding balloon protection system.
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Fig. 2. The ArteriaA (Menlo Park, CA) reverse flow protection system.
lesion and inflated during the procedure. The angioplasty balloon catheter is advanced over the microcatheter and through the guiding catheter. With the microcatheter inflated, embolic debris is aspirated through the guiding catheter. Modifications of the general concept have been made to the Theron technique with the PercuSurge, ie, a small, elastomeric balloon catheter is inserted on a distal 0.014-inch to 0.018-inch guide wire. The second type of neurological protection device is the microfilter. The filter is designed to be advanced past the lesion in a closed state and then opened during the procedure to collect embolic debris. After the procedure is completed, the filter collapses, and the particles are removed from the body. Gott et a119 developed an early vascular filter in 1968 for application during coronary bypass procedures. One of the earliest developments for a carotid filter-like system was by Wholey et al in 1988. 20 Several new companies have developed embolic filter designs based on the general principle stated above. In addition, the filter may be used on a guide wire design to allow balloon catheters and stents to be advanced coaxially along the filter wire. The various companies with filters in different stages of development include the following: 9 Angioguard (recently acquired by Cordis Johnson & Johnson, Warrenton, NJ; Fig 3) 9 Embolic Protection, Inc (recently acquired by Boston Scientific, Natick, MA; Fig 4)
\
\
Fig. 3. The Cordis Johnson & Johnson (Warrenton, NJ) (formerly AngioGuard) microfilter protection system.
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Fig. 4. The Boston Scientific (Natick, MA) (formerly Embolic Protection, Inc) microfilter protection system demonstrating an off-center lasso-type microfilter.
oMednova (recently acquired by Abbott, Abbott Park, IL; Fig 5) oACS Guidant Accunet (Santa Clara, CA; Fig 6) oMetamorphic Surgical (Pittsburgh, PA) oIntraTherapeutics (Minneapolis, MN) Which device is better suited for cerebral protection: the occlusive balloon catheter or the microfilter? Both systems must be of low-enough profile to be advanced past high-grade lesions while still functioning as a highly torquable guide wire. The use of a secondary guide wire for support across tight lesions, ie, a "buddy wire," as well as the need for predilation before filter passage is attempted, must be eliminated.
Both protection devices have advantages and disadvantages. The advantages of the balloon catheter system, such as the PercuSurge, include (1) the existence of clinical studies in both neurological and coronary systems, (2) the use of soft latex and other materials that minimally damage the artery, and (3) a high rate of removal of embolic debris.Disadvantages of the balloon system include (1) occlusion of the entire flow during all or a majority of the procedure in patients who frequently have compromised contralateral carotid artery and Circle of Willis and (2) inability to evaluate the lesion fluoroscopically while the balloon is inflated in the internal carotid artery. Advantages of an embolic filter device include (1) the ability to provide flow during the procedure while fully
Fig. 5. The Abbott (Abbott Park, IL) (formerly Mednova) microfilter protection system.
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Fig. 6. The ACS (Santa Clara, CA) Guidant Accunet microfilter protection system.
expanded and (2) that is does not require flushing. Disadvantages of the umbrella-type microfilter technique include (1) the induction of spasm or damage to the vessel wall by strong struts; (2) the risk of releasing micro particles (ie, particles < 100 [am in size); and (3) the possibility of trapped embolic particles being squeezed out the filter as it is retracted and collapsed.
Carotid Stent TechniqueWith Cerebral Protection Carotid stenting can be divided into to several steps. Regardless of whether cerebral protection is used, all patients are pretreated with aspirin (325 mg daily) and clopidogrel bisulfate (75 mg orally daily) for 3 to 5 days before the procedure. Pretreatment imaging includes a complete diagnostic angiogram including a left anterior oblique view of the aortic arch, selective carotid views of the cervical and intracerebral arteries, and a view of the vertebral arteries with attention to the circle of Willis. Additionally, cerebral computed tomography scans with contrast are obtained(Figs 7A through H). Standard retrograde access is obtained in ithe common femoral artery for all cases. Approximately 5,000 U heparin is administered to maintain ACT levels between 250 and 300. With the use of filters, it is imperative to maintain adequate heparinization. Using a 5-Fr catheter and steerable 0.035-inch guide wire, the common carotid artery is selected. Under road map images, the external carotid artery is selected whenever possible to allow for the exchange of a stiff 0.035-inch guide wire into one of the external carotid artery branches. This stiff wire serves as an anchor for advancement of an 8-Fr guiding catheter or a 6- to 7-Fr long vascular sheath into the common carotid artery approximately 2 cm caudal to the carotid bifurcation.
Under road map images, the embolic protective system is advanced past the lesion, and the filter or embolic protective balloon is deployed in the cervical or petrous portion of the internal carotid artery. For cases involving the carotid bulb, 1.0 mg atropine is administered intravenously. Over the filter or protective balloon, a 3.5- to 4.0-ram PTCA balloon catheter is advanced to predilate the lesion. Predilation helps advance the approaching stent delivery system, allowing for smoother stent placement, and provides a final check of vessel and lesion dimensions. Next, the self-expandable stent is advanced and placed into position relative to the lesion. The stent size is chosen depending on lesion and vessel characteristics. If possible, we avoid crossing into the bifurcation, but because of the less-precise nature of self-expandable stents, we frequently cross into the common carotid artery; this requires a slightly longer stent. We choose a stent approximately 1 mm larger than the diameter of the largest vessel stented. For the common carotid artery, the stent size is normally 8 to 10 m m in diameter. Tapered stents have recently become available and have been employed. With necessary injections of contrast to ensure positioning, we then deploy the stent. Afterwards, we perform angioplasty on a majority (80%) of lesions with either a 5-, 5.5-, or 6.0-mm balloon catheter. Poststent angiograms of the lesion and intracerebral angiograms are then obtained. After the procedure, patients are maintained on a regimen of 81 mg aspirin and 75 mg clopidogrel every day for 1 month.
Results Of Carotid Stenting and Cerebral Protection Since the beginning of its use, carotid stenting has had high technical success of 98% to 99% regardless of the initial use of peripheral and coronary guide wires,
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Fig. 7. (A) Initial angiogram of the thoracic aorta of a symptomatic 83-year-old man showed patent origin of great vessels and minimal tortuosity of the innominate and right common carotid arteries. (B) Visualization of a selected right common carotid artery with a 5-Fr catheter showed a high-grade (80%) lesion in the proximal internal carotid artery. (C) Under road map images, the external carotid was selected with a torquable 0.035-inch guide wire to allow advancement of 5-Fr catheter and subsequent exchange to a 0.035-inch Amplatz super-stiff guide wire. continued
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Fig. 7 continued. (D) After advancing a 7-Fr, 90-cm vascular sheath into the common carotid approximately 2 to 3 cm caudal to the bifurcation, the PercuSurge Guardwire (Medtronics, Minneapolis, MN) was carefully advanced under road map images past the lesion near the level of the petrous carotid artery. (E) The PercuSurge Guardwire balloon was inflated to ensure occlusion of the vessel, and the internal carotid lesion was predilated with a 3.5 x 2-cm percutaneous transluminal coronary angioplasty balloon catheter. (F) The Precise 6 x 30-ram stent was positioned under road map images and deployed. Next, postdilation with a 5.0 mm x 2 cm-compatible balloon catheter (0.014 inch) was performed (not shown). With the PercuSurge Guardwire balloon still inflated, a 5-Fr aspiration catheter was advanced over it, past the stent, to th~ level of the balloon catheter where blood and embolic debris was aspirated (not shown). (G) After deflation, postintervention angiograms were performed of the carotid stent. (H) Poststent angiogram (anteroposterior view) of the intracerebral arteries compared with preintervention angiogram. Anterior cerebral arterial flow was present but not seen on the preintervention angiogram.
Carotid Artery Stent Placement 9 balloons, and stents, el The rate of complications, based on minor and major strokes and procedure-related deaths, has decreased from 5.7% to 4.3% based on the results of 8,612 carotid artery stenting procedures as published in the w o r l d registry, u'21'22 With regard to non-procedure-related deaths, the total stroke and death rate has increased to 5.20%. 21 This is slightly higher than the rates reported by the major centers and takes into account the learning curve from smaller centers. During a 5-year study period, the 30-day minor stroke rate improved from 7.1% (n = 7) for the first year to 3.1% (n = 5) for the fifth year in Roubin et al's study of 528 patients, z3 Wholey et al,24 at PittsburghVascular Institute (PVI), reported a total minor and major stroke and neurological-related death rate of 3.9% (n = 20) for 513 patients treated. With the advent of embolic protection, complications associated with carotid stenting have decrease. At PVI, Wholey et a124 reviewed immediate complications with and without embolic protection and found fewer strokes and neurological-related deaths: 2.4% with protection versus 4.2% without protection. This occurred despite a relatively high rate of technical failures. Others have reported similar improvements in neurological events with cerebral protection. Reimers et a125 reported a stroke and death rate of 1.2% in 86 patients with cerebral protection; A1-Mubarek et a126 reported a 2% stroke and death rate for 162 patients in a multicenter study; and Henry et a127 reported a stroke and death rate of 2.7% for 167 patients. In our long-term follow-up of patients who had received carotid artery stents, we found the rate of ipsilateral minor and major strokes and neurologicalrelated death-free rates to be low. We reported a 3-year freedom rate from all fatal and iPsilateral nonfatal strokes, not including the 30-day periprocedural period, of 94.1% and a 5-year rate of 93.1% using the Palmaz stent. 24 Others have reported similar numbers. In a follow-up of 528 patients, Roubin et al23 performed Kaplan-Meier analysis, which revealed that the 3-year freedom rate from all fatal and ipsilateral nonfatal strokes--with and without the inclusion Of the 30-day periprocedural period--was 92_+1% and 99+_1%, respectively, Paniagua et a128 followed up 62 patients for a mean of 17 months and noted that 2.8% of patients (n = 2) suffered ipsilateral neurological events after coronary artery stenting. In long-term f011ow-up of vessel patency, there were good overall rates: for the 496 patients in the PVI study, the 3-year patency rate for the combined stent types was 91.4% using "fairly strict ultrasound c r i t e r i a . 24 Others have reported similar figures in a limited number of publications. Paniagua et al28 reported 94.3% patency in their-4ong-term follow up (mean, 17 months) of 62 patients. Dietz et a129 reported 98.5% patency in long-
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term follow-up (mean, 20 months) of 43 patients. On the contrary, Leger et al 3~ showed significant to critical recurrent stenosis in 75% of patients (n = 6 of 8) in a 20-month follow up study.
Status Of Clinical Trials Unlike with PTCA, renal, or innominate artery stenting, the Federal Drug Administration (FDA) has required that randomized trials and registries be performed to assess the safety of carotid stenting. The end points for the carotid tilter are major neurological events such as minor and major strokes and deaths. Currently, 2 randomized trials are underway in the United States. The Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) is a randomized carotid stent placement-versus-surgical endarterectomy trial that has been recently approved by the FDA. It is being initiated currently and will eventually comprise approximately 40 centers and 2,300 patients with symptomatic carotid stenoses. The stent to be used is the ACS (Santa Clara) Guidant Acculink with Accunet Filter. The second randomized trial is SAPPHIRE, which is studying stent placement versus surgical endarterectomy in high surgical-risk patients with symptomatic lesions (Tables 1 and 2). The SAPPHIRE trial uses the Cordis Precise Stent and Angioguard Filter and will comprise approximately 30 centers and 600 patients in each arm of the study. Various registries exist, most of which comprise high surgical-risk patients (Table 3). These registries include Archer, BEACH, Security, Caress, Cabernet, and Shelter. European studies include SPACE, a German trial, and EVA I!, a French study.
Conclusion Within the past 5 years, carotid stent placement has evolved as an alternative treatment for extracranial carotid artery disease. 7"a'12-1a The high technical success of the procedure, as well as its relatively low complication rate, makes carotid stenting a substitute for carotid endarterectomy for symptomatic patients, especially those with high-risk medical comorbidities. Although it is difficult to compare endarterectomy with endovascular stent placement, especially regarding generally higherrisk patients in the latter group, some early comparisons can be made. The rate of neurological complications and deaths associated with endovascular stent placement, with and without cerebral protection, in symptomatic patients is 5.36%, which is acceptable for a newly developed procedure. 22 This rate generally falls within the 6% to 7% perioperative stroke and death rate established by the AHA for symptomatic patients under-
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Table 1. High-Risk Classification Used in the SAPPHIRE, BEACH, and Security Trials
Table 2. Exclusion Criteria for Carotid Stenting Patient is experiencing an acute ischemic neurologic stroke or has experienced a stroke within the past 48 h Patient has an intracranial mass lesion (ie, abscess, arteriovenous malformation, tumor, or infection) Intraluminal thrombus Total occlusion of the target carotid artery treatment site Patient has any intracranial aneurysm (>9 mm) Previous life-threatening contrast reaction Patient is at high risk for nephrotoxicity from contrast secondary to underlying renal disease and is not yet on dialysis Patient has an uncorrected bleeding disorder Lesions not technically feasible via a percutaueous approach Patient or his or her legal representatives are unable to give informed consent Patient has long multiple lesions or complex lesions with ulcerative and/or active thrombotic changes at the carotid bifurcation as diagnosed by previous angiograms
Significant medical comorbidities CHF: III/IV LVF: <30% OHS within 6 weeks Recent MI 24 h to 30 d Unstable angina; CCS HI/IV Concurrent requirement for coronary revascularization Abnormal stress test? Severe pulmonary disease Chronic oxygen therapy Resting Po2 s 60 mm Hg Baseline hematocrit s 50% of normal FEV1 or DLCO s 50% of normal Age > 80 y Significant anatomical abnormalities Contralateral carotid occlusion Contralateral laryngeal palsy Previous radiation to head and/or neck Previous CEA recurrent stenosis Surgically difficult-to-access high cervical lesions (high cervical lesions or CCA lesions below the clavicle Severe tandem lesions Laryngectomy or tracheostomy Inability to extend head from arthritis or other Hostile neck Abbreviations: SAPPHIRE; BEACH; SECURITY; CHF, congestive heart failure; LVF, left ventricular function; OHS, open heart surgery; MI, myocardial infarction; CCS, chronic compartment syndrome; P% partial pressure of oxygen; FEV~, forced expiratory volume in 1 second; DLCO, single-breath diffusing capacity; CEA, carotid endarterectomy; CCA, common carotid artery.
g o i n g endarterectomy. 31 The rate of c o m p l i c a t i o n s incurred in stenting a s y m p t o m a t i c patients was r e c o r d e d as 2.91% in the latest survey; this n u m b e r is higher than the accepted 2.3% incurred in the A C A S study. 2-4' 22 W i t h the added safety of carotid e m b o l i c filters and o c c l u s i o n balloons, the rate of c o m p l i c a t i o n s will c o n t i n u e to decrease, especially after the initial learning c u r v e f r o m filters is o v e r c o m e and the next generations o f d e v i c e s are d e v e l o p e d .
E n d 0 v a s c u l a r stent p l a c e m e n t will g r o w in application as t e c h n o l o g i c a l i m p r o v e m e n t s in devices and e q u i p m e n t are d e v e l o p e d and as m o r e training and education o f physicians and patients occurs. T h e use o f carotid stenting is currently g r o w i n g b e t w e e n 20% and 4 0 % per year despite political and e c o n o m i c difficulties. B y the end o f the decade, the n u m b e r o f stenting procedures should equal the n u m b e r o f carotid endarterectomies performed. As the design and applicability o f stents, guide catheters, and cerebral protection d e v i c e s are i m p r o v e d , the technical success, patency, and c o m p l i c a t i o n rates will improve. Still, the important test for carotid stent placem e n t will be its l o n g - t e r m (1-, 3-, and 5-year) patency as w e l l as the results o f r a n d o m i z e d studies c o m p a r e d with the " g o l d standard" of carotid endarterectomy.
Acknowledgment The author thanks R o s e a n n B o s t at Pittsburgh Vascular Institute and R e n e R o d r i g u e z and Betty R o b l e s at U n i versity of Texas Health S c i e n c e Center at San A n t o n i o
Table 3. Current Clinical Trials and Registreries Trials Sapphire* Crest* Sheltea" Beach Caress EndoTex (Cabernet) Archer Maverick Security Bard *Randomized triall
Device
Distal Protection
5-Fr Precise 6-Fr Acculink 5.5-Fr Wallstent 5.5-Fr Carotid Wallstent 5.5-Fr Wallstent 5-Fr Nexstent 6-Fr Acculink Medtronic-AVE Xact (Abbott) 7-Fr Memotherm
Angioguard-Ex Accunet PercuSurge BSC-EPI PercuSurge BSC-EPI Accunet PercuSurge Mednova Trial stopped
Carotid Artery Stent Placement * for their managerial work; Kathy Hill, RN, Jack Buechtel, RN, and William Mook, nurses and statisticians; and the special team of nurses and technicians at Pittsburgh Vascular Institute and the University of Texas Health Science Center at San Antonio.
References 1. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis: North American Symptomatic Carotid Endarterectomy Trial collaborators. N Engl J Med 325:445-453, 1991 2. Asymptomatic Carotid Atherosclerosis Study Group. Endarterectomy for asymptomatic carotid artery stenosis. JAMA 273:1421-1428, 1995 3. Clinical Advisory: Carotid endarterectomy for patients with asymptomatic internal carotid artery stenosis. J Neurologic Sci 129:76-77, 1995 4. Clinical advisory: Carotid endarterectomy for patients with asymptomatic internal carotid artery stenosis. Stroke 25:2523-2524, 1994 5. Lusby RJ, Wylie EJ: Complications of carotid endarterectomy. Surg Clin North Am 63:1293-1301, 1983 6. Zarins CK: Carotid endarterectomy: The gold standard. J Endovasc Surg 3:10-15, 1996 7. Diethrich EB: Indications for carotid stenting: A preview of the potential derived from early clinical experience. J Endovasc Surg 3:132-139, 1996 8. Yadav JS, Roubin GS, King R et al: Angioplasty and stenting for restenosis after carotid endarterectomy. Stroke 27:2075-2079, 1997 9. Gasecki AP, Elliasziw M, Ferguson GG, et al: Long-term prognosis and effect of endarterectomy in patients with symptomatic severe carotid stenosis and contralateral carotid stenosis or occlusion: Results from NASCET. J Neurosurg 83:778-782, 1995 10. Diethrich EB: Cerebrovascular disease therapy: The past, the present, and the future. J Endovasc Surg 3:7-9, 1996 11. Wholey MH, Wholey M, Bergeron R et al: CUrrent global status of carotid artery stent placement. Cath Cardiovasc Diagn 44:1-6, 1998 12. Theron J, Courtheroux P, Alachkar, et al: New triple coaxial catheter systems for carotid angioplasty with cerebral protection. Am J Neuroradiol 11: 867-874, 1990 13. Mathias KD, Jaeger MJ, Sahl H: Internal carotid stentsPTA: 7 Year exPerience, Cardiovasc Intervent Radiol 20:I-46, 1997 (abstr) 14. Kachel R, Basche St, Heerklotz I, et al: Percutaneous transluminal angioplasty (PTA) of supra-aortic arteries especially the internal carotid artery. Neuroradiology 33:191-194, 1991 15. Wholey MH, Wholey M, Eles G, et al: Endovascular stents for carotid occlusive disease. J Endovasc Surg 4:326-338, 1997
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16. Mathur A, Dorros G, Iyer SS, et al: Palmaz stent compression in patients following carotid artery stenting. Cathet Cardiovasc Diagn 41:137-140, 1997 17. Wholey MH. Wholey M, Mathias K, et al: Global experience in cervical carotid artery stent placement. Cathet Cardiovasc Interv 50:160-167, 2000 18. Theron JG, Payelle GG, Coskun, O, et al: Carotid artery stenosis: Treatment with protected balloon angioplasty and stent placement. Radiology 201:627-636, 1996 19. Fadali AM, Topaz MM, Gott VL: A filtering device for the prevention of particulate embolization during the course of cardiac surgery. Surgery 64:634-639, 1968 20. Wholey MH, Nagurka M, Katz RS: US Patent 4,723,549. Method and apparatus for dilating blood vessels. February 8, 1988 21. Brott T, Adams HE Olinger CP, et al: Measurement of acute cerebral infarction: A clinical examination Scale. Stroke 20:864-870, 1989 22. Wholey MH, Mubarek N, Kracjier Z, et al: Updated Global Carotid Artery Stent Registry (in press). 23. Ronbin GS, New G, Iyer SS, et al: Immediate and late clinical outcomes of carotid artery stenting in patients with symptomatic and asymptomatic carotid artery stenosis: A 5-year prospective analysis. Circulation 103:532537, 2001 24. Wholey MH, Wholey M, Tan WA, et al: Long term follow up comparing balloon-mounted and self-expandable stents (in press). 25. Reimers B, Corvaja N, Moshiri S, et al: A cerebral protection with filter devices during carotid artery stenting. Circulation 104:12-15, 2001 26. A1-Mubarak N, Colombo A, Gaines PA, et al: Multicenter evaluation of carotid stenting with a filter protection system. J Am Coll Cardiol 39:841-846, 2002 27. Henry M, Henry I, Klonaris C, et al: Benefits of cerebral protection during carotid stenting with the PercuSurge GuardWire system: midterm results. J Endovasc Ther 9: 1-13, 2002 28. Paniagua D, Howell M, Strickman N, et al: Outcomes following extracranial carotid artery stenting in high-risk patients. J Invasive Cardiol 13:375-381, 2001 29. Dietz A, Berkefeld J, Theron JG, et al: Endovascular treatment of symptomatic carotid stenosis using stent placement: Long-term follow-up of patients with a balanced surgical risk/benefit ratio. Stroke 32:1855-1859, 2001 30. Leger AR, Neale M, Harris JP: Poor durability of carotid angioplasty and stenting for treatment of recurrent artery stenosis after carotid endarterectomy: An institutional experience. Vasc Surg 33:1008-1014, 2001 31. Moore WS, Barnett HJM, Beebe HG, et al: Guidelines for carotid endarterectomy: a multidisciplinary consensus statement from the ad hoc committee, American Heart Association. Stroke 26:188-200, 1995