Cerebrovascular Angioplasty and Stenting for the Prevention of Stroke
John C. Chaloupka, MD*, John B. Weigele, MD, PhD†, Sundeep Mangla, MD‡, and Walter S. Lesley, MD†
Address*Section of Interventional Neuroradiology, and Custom Stent and Interventional Radiological Device Center, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52243, USA. E-mail: [email protected]†Section of Interventional Neuroradiology, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52243, USA.‡Section of Interventional Neuroradiology, College of Physicians and Surgeons of Columbia University, 177 Fort Washington Avenue, New York, NY 10032, USA.
IntroductionStroke remains one of the leading contributors to majormorbidity and mortality in the United States, where approx-imately 700,000 new or recurrent cases are encounteredannually [1,2]. It is the third most common cause of death(behind cardiovascular disease and cancer), with over 70%of cases resulting from thromboembolic ischemia. Strokealso has become the leading cause of serious, long-term dis-ability in the United States, accounting for more than half ofall patients hospitalized for acute neurologic disease [1].
Although there are multiple etiologies of thromboem-bolic stroke, up to 30% of cases may be attributableto atherosclerosis of the cervical carotid system (primarilythe common carotid bifurcation and internal carotidbulb) [3]. Furthermore, intracranial atherosclerotic occlu-sive disease, albeit less common than extracranial carotidatherosclerosis, may cause another 8% to 10% of throm-boembolic strokes [4,5]. In certain patient populations(eg, blacks, Asians), the incidence of intracranial occlusivedisease is considerably higher [6,7••,8–10], therebyproportionately increasing the rate of attributable strokefrom this pathoetiology. Owing to a combination of ter-tiary referral patterns and differing demographic charac-teristics of the populations served by some hospitals,many cerebrovascular centers (including ours) are seeingsubstantially higher proportions of stroke victims withintracranial occlusive disease.
Consequently, for the past several decades there havebeen considerable multidisciplinary efforts toward moreprecisely defining the epidemiology, pathogenesis, naturalhistory, and optimal therapeutic approach toward strokeprevention from extracranial and intracranial cerebrovascu-lar occlusive disease. These efforts demonstrated therelationship between atherosclerotic plaque formationin various cerebrovascular locations, and the resultantcerebral ischemia from either downstream artery-to-arteryembolism or local/region hypoperfusion [11–15]. Thispathoetiologic linkage was crucial for the subsequent devel-opment of both medical and surgical therapeutic interven-tions aimed at stroke prevention. Of course, considerabletime and effort elapsed to evaluate the merits and limita-tions of various treatment paradigms, which have beenlargely driven by advances in biomedical science and tech-nology. Eventually, such interventions needed validation bylarge-scale, evidence-based, clinical trials, such as the Euro-pean Carotid Trialists Collaborative Group (ECST) [16,17],Asymptomatic Carotid Atherosclerosis Study (ACAS) [18],North American Symptomatic Carotid Endarterectomy Trial(NASCET) [19,20], Carotid Artery Surgery AsymptomaticNarrowing Operation Versus Aspirin (CASANOVA) Trial[21], and the Mayo Asymptomatic Carotid EndarterectomyStudy [22]. These clinical trials showed that one particulartreatment (carotid endarterectomy) was efficacious inpreventing stroke in properly selected patients at risk.
Until recently, stroke preventive strategies have focused on either medical regimens aimed at antagonizing or reversing atherosclerosis, or surgical intervention for revascularization of the cerebrovascular system. However, with the advent of rapidly emerging microcatheterization techniques and technology, endovascular surgical revascularization of the brain is rapidly emerging as a powerful therapeutic modality. In particular, significant advances already have been made in revascularization of the extracranial carotid artery and many common anatomic sites of intracranial athero-occlusive disease, using special adaptations of conventional percutane-ous angioplasty and stenting techniques. This paper reviews the cumulative experience with these emerging techniques, with a particular emphasis on clinical outcomes and future directions. It also reports the substantial cumulative institutional experience of the authors over the past 18 months with both extracranial carotid and intracranial artery stent-assisted carotid angioplasty.
40 Stroke
However, despite the documented successes of certaintherapies in preventing thromboembolic stroke, thereremains considerable room for improvement. For example,although most large clinical trials have shown thatlow complication rates of carotid endarterectomy (CEA)can be achieved in certain symptomatic and asymptomaticgroups, there are many patients who are at substantiallyhigher risk (at least 10%) for serious perioperativemorbidity or mortality [23]. These include patientswith contralateral carotid occlusion, severe coronary arterydisease (CAD), other significant medical comorbidities(eg, chronic obstructive pulmonary disease, obesity),unstable neurologic status, and recurrent stenosis afterCEA [23]. Furthermore, many types of extracranial occlu-sive lesions present difficulties related to limited opensurgical access (eg, stenoses of the internal carotid artery[ICA] distal to the bulb, proximal common carotid artery[CCA], and entire vertebral artery), which also results insubstantially higher perioperative risk that may be exces-sive to the relative benefits of intended stroke prevention.For all intracranial occlusive lesions, the situation is farworse, whereby surgical access and techniques for directrevascularization are either impossible or associated withexcessive risk of major neurologic morbidity or mortality.Indirect surgical revascularization techniques (typically viaextracranial to intracranial bypass operations) also havebeen shown in a large clinical trial to be of no significantbenefit [24,25]. Finally, the best medical management,including systemic anticoagulation and antiplatelettherapy, is still associated with a very high cumulative riskof stroke. For example data from the EC/IC bypass studyestimated this risk to be as high as 8% per year [25].
Owing to the above-mentioned shortfalls in bothmedical and surgical management of cerebrovascularocclusive disease, there has been growing interest andeffort in expanding the role of endovascular surgery forrevascularization of both extracranial and intracraniallesions using such modalities as percutaneous trans-luminal angioplasty (PTA) and stenting. As technique andtechnology have evolved over this period, it has becomeclear that these therapeutic modalities are increasinglyuseful for the management of certain types of cerebro-vascular occlusive disease. In this paper we review thecumulative clinical experience of these efforts and comparethem with our institution’s most recent experience.
Review of Clinical OutcomesExtracranial circulationThe value of endarterectomy for symptomatic carotidartery stenosis, and the success of PTA in coronary, renal,iliac, and peripheral arteries led to an interest in carotidartery angioplasty as a less invasive alternative to surgicalendarterectomy. Enthusiasm was tempered, however, byconcerns for the risks of acute thrombosis, arterial dissec-tion, distal emboli, and delayed restenosis, which could be
more catastrophic and less salvageable in the target organ(brain) than in other vascular beds. The possible benefitsof carotid angioplasty or stenting compared with endarter-ectomy might include lower periprocedural morbidity/mortality, equal or better stroke prevention, lower costs,and better patient acceptance [26].
In 1980, percutaneous angioplasty of an atheroscleroticstenosis of a CCA origin was published [31]. Several casereports and small series followed, including angioplasty ofcarotid bifurcation atherosclerotic stenosis [27–30]. Thefirst large case series was published in 1986. Twenty-sevenpatients underwent carotid angioplasty for atherosclerosis,fibromuscular disease, and Takayasu’s disease. All of theprocedures were successful, without morbidity or mortality.No recurrent symptoms occurred in 3 months to 4 years offollow-up [32]. A large, single institution study in 1996reported percutaneous angioplasty of 85 high-gradesymptomatic carotid stenoses over a 4-year period. Thetechnical success rate was 92% (less than 50% residualstenosis). The 30-day mortality rate was 0%, and 30-daymorbidity rate was 4.9% [33].
In spite of the favorable results obtained with carotidangioplasty, theoretical advantages of vascular stentshave held strong appeal to endovascular surgeons. Theseinclude the prevention of elastic recoil, arterial dissec-tions, and distal emboli, as well as possible lower rest-enosis rates. Supporting the concept, coronary arterystents were reported to result in higher technical successrates, lower rates of acute occlusions, and lower resteno-sis rates than coronary angioplasty. For these reasons,most of the recent series on carotid endovascular inter-vention have reported primary stenting of the carotidartery, although these advantages compared with angio-plasty remain unproven [26,34].
A number of large carotid artery stenting reports werepublished between 1996 and 1999, most of which wererelated to stroke prevention of athero-occlusive disease[35–49]. In addition, a few reports were published regard-ing the use of stenting for stroke prevention in otherdiseases, such as carotid blowout syndrome, radiation-induced occlusive disease, carotid dissection, and fibro-muscular dysplasia [50–52]. Phatouros et al. [53••]summarized the results of 11 of the larger publishedstudies, which comprised over 800 total patients. Thisreview noted that a true meta-analysis of outcomes wasdifficult because of various inconsistencies in the selectedpatient populations, lesion characteristics, endovasculartechniques, and results terminology. The overall reportedtechnical success rate exceeded 95%. Procedure-relatedmortality ranged from 0.6% to 4.5%, major stroke rateswere from 0% to 4.5%, minor stroke rates were from 0%to 6.5%, and 6-month restenosis rates were less than 5%.The stroke and death rates compared favorably with theNASCET [19,20] and ECST data [16,17]. This is particu-larly notable because in five of the studies, 80% of 574patients did not fulfill the inclusion critieria for these
Cerebrovascular Angioplasty and Stenting for the Prevention of Stroke • Chaloupka et al. 41
endarterectomy trials owing to comorbidities [53••].The reported 6-month restenosis rate of less than 6%compared well with the reported postendarterectomycarotid artery restenosis rate of 10% in the first year, 3% inthe second year, and 2% in the third year [54].
Wholey et al. [55••] recently surveyed the global statusof carotid artery stenting. Between February and June,1997, surveys were sent to 29 major carotid stent centersthroughout the world, who were identified by publica-tions, presentations, and discussions at meetings. Therewere 24 respondents (86%). As of June, 1997, a total of2048 patients had undergone carotid stent deployment atthose centers. The average percentage of symptomaticpatients was 66.4% (range, 47% to 100%). The overalltechnical success rate (less than 30% residual stenosis) was98.6%. The rate of major strokes was 1.32% (0% to3.85%). The rate of minor strokes was 3.08% (0% to 7%).The average perioperative (30-day) mortality rate was1.37% (0% to 6.9%). The combined average major andminor stroke and death rate was 5.77%. The most com-monly used stents were the Palmaz (53%) (Cordis, Warres,NJ), Wallstent (39%) (Boston Scientific, Boston, MA), andStrecker (8%) (Boston Scientific, Boston, MA). Stent defor-mations were exclusively reported with the Palmaz stent(1.4% at 6 months). Only two centers used cerebral protec-tion. The overall restenosis rate (greater than 50% stenosis)was 4.8% at 6 months [55••].
In contrast, there have been two recent reports with lessfavorable carotid stent complication rates. A prospective,consecutive, randomized trial of endarterectomy versuscarotid stenting in a single institution was stopped becauseof unacceptable morbidity after 17 patients. Five of sevenstent patients had periprocedural strokes. Three strokeswere disabling at 30 days. None of the 10 endarterectomypatients had a neurologic deficit or perioperative death[56]. This study suffered from a critical flaw in that theendovascular operator had no prior experience or trainingwith carotid stenting, raising serious doubts concerningthe validity of the study. Jordan et al. [57] performed aretrospective comparison of carotid stenting in 312 patientsand endarterectomy with local anesthesia in 121 patients.There were 11 transient ischemic attacks (TIAs) (4.1%), 23strokes (8.6%), and three deaths (1.1%) in the stent groupcompared with two TIAs (1.8%), one stroke (0.9%), and nodeaths (0%) in the endarterectomy group [57].
The suggestion that carotid stenting may be more costeffective than endarterectomy has been challenged.Jordon et al. [58] compared the total hospital charges forcarotid balloon angioplasty and stenting to endarterec-tomy. During a consecutive 14-month period, 239 carotidartery stenoses were electively treated, 109 by stenting and130 by endarterectomy. In the stent group, there wereeight total strokes (7.7%) (six minor, two major), and onedeath (0.9%). In the endarterectomy group, there weretwo strokes (1.5%) (1 minor, 1 major) and two neurologicdeaths (1.5%). Total hospital charges per admission were
$30,140 for the stent group and $21,670 for the endarter-ectomy group. Excluding the charges for care of complica-tions, the respective hospital charges were $24,848 forstenting and $19,247 for endarterectomy. Catheterizationlab charges averaged $12,968 versus $4,263 for operatingroom charges. The details of the catheterization labcharges were not provided [58].
There is limited validity in directly comparing theresults of carotid stent series and endarterectomy data,because there are often significant differences in the ageand medical conditions of patients who undergo the twoprocedures. Many carotid stent patients would not havequalified for the NASCET, ECST, and ACAS trials becauseof older age or serious medical comorbidities. The endart-erectomy clinical trials all rigorously selected relativelyyoung, healthy patients. It is also doubtful that the endart-erectomy trial statistics are typical of general endarte-rectomy results in the United States [38]. Patients withadvanced age or with serious additional medical problemswho undergo endarterectomy have significantly higherperioperative morbidities and mortality than the NASCETand ECST trial patients [2,23,59]. A recent study showedthere was a significantly higher death rate for unselectedMedicare patients undergoing carotid endarterectomy atthe same institutions participating in the NASCET andACAS studies than for the original study participants(NASCET 0.6%, ACAS 0.1%, unselected 1.4%). The perio-perative mortality rates for nontrial hospitals were evenhigher; 1.7% for high-volume institutions, 1.9% foraverage-volume institutions, and 2.5% for low-volumeinstitutions. These data likely reflect differences in selec-tion criteria (high-risk patients) and surgical expertise [59].
Conners et al. [60•] noted that there a number of newdrugs available to treat atherosclerosis and prevent strokesthat have appeared since the endarterectomy clinicaltrials, including new oral antiplatelet agents (eg, ticlopi-dine, clopidigrel), lipid-lowering agents (HMG-CoA reduc-tase inhibitors), antiplatelet aggregators (glycoprotein IIb/IIIa receptor inhibitors), and treatments for hyperho-mocysteinemia. Although the NASCET and ECST trialsused the best medical therapy of the time (aspirin), it wasnot optimal medical therapy by current standards. Thepotential benefits or lack thereof for both endovascularand surgical carotid interventions compared with contem-porary medical therapy are unknown [60•].
Beebe [61] points out that the clinical carotid stentliterature is largely anecdotal. A peer-reviewed, externallyadjudicated, randomized trial comparing carotid stent-ing and endarterectomy has never been published. Thecarotid stent articles consist of abstracts, anecdotalreports, and largely anecdotal clinical series. Problemsinclude small numbers and incomplete data on condi-tions, selection criteria, and follow-up. Often patientswith dissimilar histories, stroke risks, and types oflesions are grouped together. The potential for investi-gator bias is often present. Although the published
42 Stroke
data support the premise that carotid stenting can beperformed reasonably effectively and safely, they cannotbe used to prove the hypothesis that carotid stenting isequal or superior to endarterectomy [61]. Hobson [62]further observed that the current literature on carotidangioplasty and stenting only qualifies for level IV orlevel V evidence and grade C clinical recommendations.No level I or II studies have been conducted, and nograde A or B clinical recommendations are available.
These issues are being addressed. The Carotid andVertebral Angioplasty Study (CAVATAS) is a large, prospec-tive, randomized, multicenter European trial comparingcarotid angioplasty with endarterectomy. The trial hasbeen completed but not yet published. A preliminaryreport at a meeting in 1998 indicated there was no signifi-cant difference in the rate of stroke or death between thetwo techniques [53••]. A multicenter, prospective,randomized, clinical trial recently has been funded by theNational Institute for Neurological Disorders and Stroke,National Institutes of Health to compare the clinicalefficacy of carotid revascularization by endarterectomyversus endoluminal stenting (Carotid RevascularizationEndarterectomy vs Stent Trial [CREST]). The study willenroll approximately 3000 patients in 50 participatingcenters. The endovascular surgeons will be requiredto complete a formal credentialing phase. The primaryoutcome events will be a) any stroke, myocardial infarc-tion, or death during the 30-day perioperative period; orb) ipsilateral stroke after 30 days. Secondary goals include1) comparison of 30-day perioperative morbidity/mortal-ity for the two procedures; 2) comparison of the postoper-ative morbidity/mortality for the two procedures; 3)restenosis rates; 4) identification of high-risk subgroupsfor both procedures; 5) comparison of quality of life andcosts; and 6) report outcome differences and complica-tions by stent type, technique, and experience [62,63].
Although there has been resistance in the surgical com-munity to endorse carotid angioplasty and stenting ascomparable with endarterectomy, there are some acceptedindications. These include surgically inaccessible lesions(intrathoracic, high cervical), nonatherosclerotic pathology(fibromuscular disease, post-radiation angiitis, post-endart-erectomy restenosis, dissection), and high-risk patients[64,65]. In 14 patients with radiation-induced extracranialcarotid artery stenosis, stenting was technically successful in100%, with a reduction in mean stenosis from 77% to 8%.There was one minor stroke with complete recovery in 2days, no major stroke, and no procedural mortality. Therewas no restenosis in the nine patients imaged at 6 months offollow-up [50]. In 17 postendarterectomy restenoses, carotidstenting was technically successful in 100%, with no periop-erative stroke or death. In comparison, surgical repair of 16carotid restenoses was technically successful in 100%, withno stroke or death, and one recurrent laryngeal nerve palsy[66]. Lanzino et al. [67] reported angioplasty (n=7) or angio-plasty with carotid stenting (n=18) for 25 patients with
carotid artery restenosis following endarterectomy. There wasone TIA, and there was no major stroke or death. Stentingyielded better technical results and a lower restenosis rate(one out of 18) [67]. Liu et al. [68] reported technically andclinically successful stent placement in seven patients forcarotid dissection. All remained asymptomatic and withoutrestenosis at a mean 3.5 years of follow-up [68]. Bejjani et al.[51] reported successful treatment of five symptomaticcarotid dissections with complete long-term recovery.
The technical aspects of carotid stenting are evolving.Ongoing chal lenges include the development ofimproved stents optimized for the carotid artery and theprevention of procedure-related cerebral emboli. Mathuret al. [69] reported 14 patients with deformed Palmazstents on a 6-month routine angiographic follow-up.Some patients required repeat intervention. As a result ofthese and similar observations, there has been a trendtoward the use of less deformable, self-expanding stentssuch as the Wallstent or Smart Stent (Cordis, Miami, FL).A new generation of stents optimized for the carotidbifurcation is under development [70].
The current major concern of carotid stenting is therisk of embolic stroke. An ex vivo carotid bifurcationmodel was developed to quantify the emboli produced bycarotid stenting and to correlate the embolic risk withplaque morphology [71]. Human carotid plaquesobtained during endarterectomy were dilated and stentedin the model. Both the Palmaz stent and the Wallstentwere studied. Every experimental dilatation and stentinggenerated emboli, ranging in number from two to 126particles (median of 15), and ranging in size from 120 to2100 mm (mean of 338 mm). The emboli consisted of ath-erosclerotic debris, organized thrombus, and calcifiedmaterial. Sonographically echolucent plaques andstenoses greater than or equal to 90% produced moreemboli [71]. Manninen et al. [72] compared balloonangioplasty with stent placement in human cadavercarotid arteries in situ. Unexpectedly, both techniquescaused the same frequency and severity of embolization.The largest embolic particles were intimal strips measur-ing up to 5 mm in diameter, occurring in all stent deploy-ments and most balloon angioplasties [72].
A cerebral protection device has been described toprevent cerebral emboli during carotid stenting. Theron et al.[73] designed a triple coaxial catheter system forcerebral protection against emboli during angioplasty basedon temporary distal internal carotid occlusion. The cerebralprotection was reported to reduce distal embolic complica-tions from 8% in 38 patients undergoing angioplasty with-out the device to 0% in 43 patients with the distalballoon protection device [45]. Few groups, however, haveadopted the technique [55]. This has likely been due to therather cumbersome nature of the system and complicationsattributed to the device [40]. Additional cerebralprotection systems are currently under development, andmay further improve the safety of carotid stenting [53••].
Cerebrovascular Angioplasty and Stenting for the Prevention of Stroke • Chaloupka et al. 43
Intracranial circulationIn sharp contrast to the extracranial carotid circulation, theuse of stents in the intracranial arteries has been signifi-cantly delayed. The relatively large and stiff catheters andguidewires of both the distant and recent past wereincapable of negotiating tortuous, delicate intracranialarteries. In addition, the risks of complications were formi-dable and included arterial dissection, embolus, thrombo-sis, and rupture, potentially resulting in stroke and death.
The early intracranial angioplasty literature consistedof scattered pioneering case reports that mostly high-lighted the promises and significant limitations/risks ofthe technique. Sundt et al. [74] were probably first to reporttwo successful cases of basilar artery angioplasty performedin 1980. Both patients had severe basilar artery stenosesand progressive, intolerable, vertebrobasilar neurologicsymptoms despite maximal medical therapy. One patienthad failed multiple surgical bypasses. The relative inflexi-bility of the available catheters and guidewires of that eranecessitated an operative exposure of the suboccipitalvertebral artery at C1-C2 to gain vascular access. Bothpatients experienced postprocedural TIAs, but otherwisehad good clinical responses [74]. The same group,however, reported a similar case several years later, whichresulted in the delayed onset of a basilar artery pseudoan-eurysm and rupture that was fatal [75]. Subsequently,Higashida et al. [76] reported an unsuccessful percutane-ous transfemoral attempt to balloon dilate tandem basilarartery stenoses, followed by an angioplasty via operativeexposure of the C1-2 vertebral artery that was technicallysuccessful, but resulted in a brainstem infarct.
The first anterior circulation intracranial angioplastywas reported in 1984. A transfemorally placed coronaryangioplasty balloon catheter was successfully used to dilatea symptomatic cavernous carot id s tenos is [77] .A subsequent report described use of a relatively softsilicone elastomer balloon catheter (designed to treatvasospasm) to dilate an atherosclerotic middle cerebralartery stenosis. Following transient vasospasm, there wasan enlarged vascular lumen. A Tc-99m HMPAO singlephoton emission computed tomography (SPECT)cerebral blood flow (CBF) study showed increased flow tothe middle cerebral artery distribution, the first directdemonstration of improved cerebral perfusion followingintracranial angioplasty [78]. Subsequent successful casereports of petrous carotid and basilar artery angioplastyappeared [79,80]. The petrous carotid artery had under-gone progressive remodeling and was widely patent at 2-year angiographic follow-up. The basilar artery wasoccluded on 6-month angiography, but the patient wasasymptomatic. The authors speculated that the angioplastyallowed sufficient time for adequate collateral formation.
Additional case reports and a number of retrospectiveseries, including from several to 70 patients, have beenpublished in the past few years. All of the studies have beenhistorical and uncontrolled. No prospective, randomized,
controlled trial comparing intracranial angioplasty withmedical or open surgical therapy has been published.In spite of these important limitations, the recent literaturehas provided valuable information on a number ofkey scientific issues, including appropriate patient selec-tion, operative technique, technical and clinical success,complications, and restenosis.
Touho [81] reported a series of 19 attempted intra-cranial carotid artery angioplasties in symptomatic patients(TIA or prior cerebrovascular accident with unstable neuro-logic symptoms on maximal medical therapy). Theprocedure was successful in 13 patients (68.4%). Themean stenosis was reduced from 83.1% before theangioplasty to 35.8% after the procedure. Seven of the 13patients demonstrated clinical improvement. All of thepatients who responded had below normal cerebral perfu-sion and abnormal vasodilatory response on preprocedurerCBF SPECT, whereas most of the nonresponding patientsdid not. He suggested this may be of value in patient selec-tion. There was a 38.5% restenosis rate at 6 to 12 monthsof follow-up [81].
Improved microcatheters and micro-guidewires havebeen used more recently for successful transfemoral percu-taneous angioplasty of basilar artery stenoses. One casereport described a successful basilar artery angioplasty withno symptoms at 12-month follow-up. The authorssuggested complications may be minimized by gentle,short inflations [82]. Terada et al. [83] described verte-brobasilar angioplasty in 12 patients. Eight (67%) weresuccessful without complications. There were two iatro-genic dissections with permanent infarcts, one ultimatelyleading to death from a brainstem infarction. There weretwo thromboembolic complications with TIAs. Meanstenosis decreased from 84% to 44%. Restenosis occurredin two patients [83]. Nakatsuka et al. [84] also reportedtwo successful basilar artery PTAs with no new neurologicdeficits at 10 and 13 months after the angioplasties. Theyemphasized the use of low-pressure, submaximal PTA withan undersized balloon diameter to minimize risk.
Mori et al. [85] demonstrated the technical feasibilityof reopening chronic total MCA occlusions, successfulin four occlusions less than 3 months old and unsuccess-ful in two occlusions more than 3 months old. Therewere no complications.
Several small series combined both anterior and poste-rior circulation PTAs. McKenzie et al. [86] reported intrac-ranial angioplasty for 12 atherosclerotic stenoses and fivevasculitis-induced stenoses. Although 16 of 17 lesionsdemonstrated initial improvement, all five of the stenosescaused by vasculitis rapidly recurred and progressed tocomplete occlusion. Eleven of 12 patients with atheroscle-rotic lesions were clinically improved at 12 months. Theauthors suggested that intracranial PTA for vasculitis is notrecommended [86]. Callahan and Berger [87] reported aseries of 15 patients. Intracranial angioplasty was techni-cally successful in all but one (fatal ICA rupture). There
44 Stroke
was also one PTA-induced brainstem infarction. There wasno restenosis or symptom recurrence over more than 24months [87]. Takis et al. [88] reported a small series with ahigher complication rate. Eight of 10 intracranial angio-plasties were technically successful; however, there werefive cases of vasospasm resulting in two infarcts, anddissections causing strokes in two other patients. Yokoteet al. [89] reported 17 cases of intracranial PTA. Fourfollowed intra-arterial thrombolysis. Sixteen of 17 weretechnically successful. There was one fatal MCA reocclu-sion caused by a dissection. Restenosis occurred in 25% ofpatients during a mean 14-month follow-up [89].
Several series have focused on follow-up. Mori et al.[90] characterized the short- and intermediate-termpatency rates in a series of 35 patients undergoing intracra-nial PTA. Twenty-seven procedures were technicallysuccessful. There were three permanent complications. Therestenosis rate at 3 months was 29.6%. For patients with-out significant restenosis at 3 months, all remained free ofrestenosis at 12 months. Restenosis was more commonwith severe, eccentric lesions, extreme angulation oflesions, and total occlusions [90]. Marks et al. [91••]reported 16 to 74-month clinical follow-up in a series of23 patients, 21 of who had technically successful intracra-nial angioplasties. There was one fatal vessel rupture, andone stenosis could not be crossed. There was one stroke inthe in the same vascular territory as the angioplasty duringthe follow-up period, an annual rate of 3.2%. The authorssuggested intracranial angioplasty reduces the risk of futurestroke in patients with symptomatic stenoses [91••]. In adifferent study, Mori et al. [92] compared follow-uppatency rates with lesion morphology to find the attributesof atherosclerotic lesions most amenable to angioplasty.Lesions were assigned to three groups: type A—short(5 mm or less in length), concentric or moderatelyeccentric, and less than totally occlusive; type B—5 to 10mm in length, extremely eccentric, or totally occluded atless than 3 months; and type C—more than 10 mm inlength, extremely angulated, or totally occluded at morethan 3 months. Clinical success rates for type A, B, and Clesions were 92%, 86%, and 33%, respectively. Cumulativerisks of stroke or bypass surgery for type A, B, and C lesionswere 8%, 26%, and 87%, respectively. The authors con-cluded type A lesions are the most favorable for intracra-nial angioplasty. Restenosis at 1 year for type A was 0%(92% follow-up), for type B was 33% (86% follow-up),and type C was 100% (33% follow-up) [92].
Conners et al. [7] retrospectively reviewed a 9-yearexperience of 70 intracranial angioplasties with specialattention to procedural technique. Cases were assignedto three time periods, which employed evolving tech-niques. In the early period, angioplasty was moderatelyrapid and brief. The balloon was sized slightly smallerthan vessel diameter. In the middle period, angioplastywas extremely rapid and brief. The balloon was sized toequal or slightly exceed the vessel diameter. In the latest
period, the balloon was undersized and inflation wasextremely slow (several minutes). Clinical improvementoccurred in 87.5% of cases in the early period, 83.3% ofthe cases in the middle period, and 98% of cases in thelatest period. Complications including dissection, abruptocclusion, and death were most common in the middleperiod (extremely rapid and brief inflation, slight over-sizing permitted). Extremely slow balloon inflation andballoon undersizing yielded the fewest complicationsand best clinical results. These authors also advocatedthe use of a platelet glycoprotein IIb/IIIa receptor inhibi-tor such as abciximab during the procedure, as well asoral aspirin, oral nimodipine, and intravenous heparin.The angioplasty site was periodically observed for 1 hourfollowing the PTA for possible thrombus formation.After the procedure, these patients were maintained onticlopidine and aspirin [7].
A summary of the literature is presented in Table 1.Since the original report by Sundt et al. [74] in 1980, over300 cases of intracranial angioplasty have appeared in theliterature. All of the published series have uniformlyselected symptomatic patients experiencing recurrent TIAsor prior infarcts with continued neurologic symptoms inspite of maximal medical therapy (anticoagulation, anti-platelet medication). Two thirds of the PTAs have been inthe anterior circulation (distal intracranial internal carotid,anterior and middle cerebral arteries), and one thirdhave been in the posterior circulation (vertebrobasilarsystem). The overall reported technical success rate is 84%.Of interest, the technical success rate in cases reported upto 1995 was 74%, whereas the technical success rate inseries reported from 1996 to the present has improved to88%. This reflects greater surgical experience, as well asimproving techniques and equipment. The overall clinicalsuccess rate mirrors the technical success rate at 84%. Thisis strong evidence that appropriate candidates have beenselected for intracranial angioplasty; therefore, a successfulprocedure is highly likely to have therapeutic value. Majorcomplications have occurred in 13% (TIA, infarct, vesselocclusion, vasospasm, embolus, symptomatic dissection,rupture). There have been six reported deaths (2%), andfour reported vessel ruptures (1.4%). Recent improvementsin equipment and technique are decreasing complicationrates. Long-term patency rates have yet to be determined.However, short- and intermediate-term rates of restenosiscompare favorably with other vascular systems.
Intracranial StentingSince the initial clinical introduction of the peripheralarterial Palmaz stent in the late 1980s, there has been adramatic, continually increasing use of stents in the coro-nary, renal, and iliac arteries as data accumulates thatvascular stents improve the initial angioplasty technicalresults, can repair angioplasty complications (dissections),and may improve long-term patency rates. The recent
Cerebrovascular Angioplasty and Stenting for the Prevention of Stroke • Chaloupka et al. 45
introduction of second generation coronary stents withlower profiles, greater flexibility, and improved tractabilityin the past several years has resulted in preliminary appli-cations in the intracranial arteries.
The first published report of use of an intracranialstent for atherosclerotic occlusive disease appeared in1996, in which a patient with a symptomatic 99% stenosisof the petrous segment of the internal carotid arterywas treated. The stenosis was initially predilated with a 4-mm diameter Bandit angioplasty balloon (SciMed, MapleGrove, MN). The post-PTA appearance was described as“better but hazy", prompting use of a 4-mm Palmaz-Schatz coronary stent, which was eventually deployedafter "moderate resistance" to advancement was encoun-tered. The patient had no immediate complicationsand remained symptom-free at a 4-month follow-up.The authors acknowledged that the indication for stentdeployment was controversial, but strongly believed itsuse not only created a better angiographic result, but alsolowered the risk of an acute arterial occlusion, and mayhave been associated with a lower restenosis rate [93].
Dorros et al. [94] subsequently described the use of aPalmaz-Schatz coronary stent to salvage an angioplasty-induced flow-limiting dissection of the petrous carotidartery. They described "much difficulty" advancing therelatively stiff catheter across the site, however, the proce-dure was successful. The artery was widely patent on thepost-stent angiogram. The patient remained asymptom-atic on 5-month follow-up and there was no restenosis onfollow-up angiography [94].
The development of second-generation coronary stentswith greater flexibility, lower profiles, and superior trackabil-ity has increased the feasibility and appeal of intracranialstent deployment. A Cook GRII (Cook, Bloomington, IN)second-generation coronary stent was used to improve aresidual post-angioplasty stenosis in the petrous/precavern-ous internal carotid artery from 57% to 8% [95]. Phatouroset al. [96] reported a case of an acute vertebrobasilar throm-bosis superimposed on a severe proximal basilar arterystenosis. The acute clot was successfully lysed with uroki-nase, however, there was a minimal response of the underly-ing s tenos is to angioplas ty, ra i s ing concern fo rrethrombosis. A GRII stent was deployed across the stenosiswith an excellent angiographic result. The patient had agood neurologic recovery, but unfortunately died of unre-lated cardiogenic shock and sepsis soon after the procedure.GFX (AVE, Santa Rosa, CA) stents have been used in severalcases, including a high-grade, eccentric, intracranial vertebralartery stenosis [97], a severe proximal basilar artery stenosis[98], and a 90% petrous carotid artery stenosis [99], all withgood technical and clinical results.
Reliable intracranial stents represent a powerful "bail-out" tool for angioplasty-related failures and complica-tions. Malek et al. [100] reported a delayed iatrogenic dis-section of the entire basilar artery 2 days after an initiallysuccessful vertebral artery PTA/stent, which was success-
fully repaired with a second tandem GFX stent positionedto tack down the entry point of the dissection. The patientmade a good clinical recovery. In another case, an acutebasilar artery occlusion was successfully recannalized withchemical thrombolytic, uncovering an atheroscleroticstenosis. Unfortunately, the artery repeatedly occludedafter multiple balloon dilatations. A Cook flex stent wasplaced successfully, restoring antegrade flow [87].
Several small series of intracranial stents deployedfor atherosclerotic occlusive disease have been recentlypublished. Morris et al. [101] reported three successfulcases of intracranial PTA and GFX stent deployment. Thefirst case involved a flow-limiting angioplasty-induceddissection of a symptomatic cavernous carotid athero-sclerotic stenosis, successfully repaired with a stent deploy-ment. Two intracranial vertebral artery stenoses weresuccessfully treated with PTA and stent placement. Therewere no complications, and all of the patients were asymp-tomatic on short-term follow-up [101]. Horowitz et al.[102] reported angioplasty and stenting (GFX, Multilink[Guidant, Temecula, CA]) of three symptomatic mid-basi-lar stenoses without complication. This was followed by alarger series by Gomez et al. [103], who reported 12patients who underwent elective stenting (Microstent II[Ave, Santa Rosa, CA], GFX, Multilink Duet (Guidant,Temecula, CA) of symptomatic basilar artery stenoses. Allcases were technically successful. Mean stenosis wasreduced from 71.4% to 10.3%. There was one case of post-procedural sixth and seventh nerve palsies with diplopia,which resolved within 8 weeks. No other postproceduralcomplications were noted. Another patient had a recurrentTIA at 4 months. Repeat angiography revealed a proximalbasilar artery occlusion, which was successfully recannal-ized. All of the other patients remained asymptomatic onclinical follow-up at 0.5 to 16 months (mean, 5.9 months)[103]. Mori et al. [104•] reported 12 attempted stent (GFX,Multilink) deployments in the intracranial vertebral,carotid, and basilar arteries, which were technically suc-cessful in 10. Two vertebrobasilar cases failed due to proxi-mal arterial tortuosity and inability to advance the stentsacross the lesions. Mean stenosis was reduced from 80% to7%. No complications occurred. Three-month angio-graphic follow-up in all patients demonstrated a meanstenosis of 19%, without a single significant (greater than50%) restenosis. All patients remained asymptomatic on 8-to 14-month clinical follow-up [104•]. Rasmussen et al.[105] reported stent-assisted (GFX, Duet) angioplasty ofeight symptomatic intracranial vertebrobasilar stenoses.One patient had a dissection proximal to the stent anddied of a massive subarachnoid hemorrhage the eveningof the operation. All of the other cases were technicallyand clinically successful, remaining asymptomatic at upto 8-months of follow-up. Mean stenosis decreasedfrom 84% to 7% [105].
A summary of the current intracranial stent literature ispresented in Table 2. Forty-seven cases have been reported.
46 Stroke
Tab
le 1
.S
um
mar
y o
f clin
ical
rep
ort
s o
f in
trac
ran
ial P
TA
Stu
dy /
year
Ste
nose
s / l
ocat
ion
Tec
hnic
al s
ucce
ssC
linic
al s
ucce
ssC
ompl
icat
ions
Med
icat
ions
Fo
llow
-up
Sund
t et
al.
[74]
/ 19
802
/ BA
2/2
2/2
Post
-pro
cedu
re T
IAs,
m
inor
per
fora
tor
pont
ine
infa
rct
LMW
dex
tran
, di
pyri
d, v
erap
amil
Clin
ical
ly s
tabl
e at
5
mo,
7 w
k
O’L
eary
and
Clo
use
[77]
/ 19
841
/ IC
A1/
11/
1N
one
Hep
arin
Clin
ical
ly s
tabl
e at
1 y
Hig
ashi
da e
t al.
[76]
/ 19
87
1 / B
A1/
10/
1Br
ains
tem
infa
rct
Hep
arin
Non
e
Purd
y et
al.
[78]
/ 19
901
/ MC
A1/
11/
1T
rans
ient
vas
ospa
smH
epar
inA
ngio
grap
hic
rest
enos
is a
t 3
d,
clin
ical
ly s
tabl
e at
2 m
oR
osto
mily
et a
l. [8
0] /
1992
1 / I
CA
1/1
1/1
Non
eH
epar
inA
ngio
grap
hica
lly
pate
nt a
nd c
linic
ally
st
able
at
2 y
Ahu
ja e
t al.
[79]
/ 19
921
/ BA
1/1
1/1
Post
-pro
cedu
re T
IAs
Hep
arin
Ang
iogr
aphi
cally
oc
clud
ed a
t 6
mo,
cl
inic
ally
sta
ble
Tou
ho
[81]
199
519
/ 8
ICA
, 9
MC
A, 2
AC
A13
/19
7/13
1 as
ympt
omat
ic
diss
ectio
n, 2
tra
nsie
nt
neur
olog
ic d
efic
its
Hep
arin
38.5
% a
ngio
grap
hic
rest
enos
is
at 6
–11
mo
Ter
ada
et a
l.[8
3] /
1995
12
/ 7
VA
, 4 B
A,
1 V
A&
BA8/
128/
122
diss
ectio
ns (
1 in
farc
tion,
1 d
eath
), 2
thro
mbo
embo
lic
infa
rcts
, 2 T
IAs
Hep
arin
10/1
1 cl
inic
ally
as
ympt
omat
ic
at 2
y, a
ngio
grap
hic
rest
enos
is 2
/7
at 6
mo
Hou
dart
et a
l. [
82]
/ 199
6 1
/ BA
1/1
1/1
Tra
nsie
nt S
AH
Hep
arin
Clin
ical
ly s
tabl
e at
12
mo,
no
angi
ogra
phic
re
sten
osis
at
6 m
oN
akat
suka
et a
l.[8
4] /
1996
2 / 2
BA
2/2
2/2
Non
eU
nrep
orte
dC
linic
ally
sta
ble
at 1
0 an
d 13
mo
McK
enzi
e et
al.
[86]
/ 19
9617
/ 8
ICA
, 1 A
CA
, 2
MC
A, 4
VA
, 2 B
A16
/17
11/1
2 at
hero
scle
rosi
s;
0/5
vasc
uliti
s 1
sym
ptom
atic
dis
sect
ion
Hep
arin
11/1
2 at
hero
scle
rotic
le
sion
s cl
inic
ally
im
prov
ed a
t 1
yC
alla
han
and
Berg
er
[108
] / 1
997
15 /
9 IC
A, 3
MC
A,
1 V
A, 2
BA
14/1
513
/15
1 ve
ssel
rup
ture
-dea
th, 1
br
ains
tem
infa
rct
Nife
dipi
ne,
hepa
rin,
ASA
0/14
res
teno
sis
at
24 m
o, c
linic
ally
st
able
Tak
is e
t al.
[88]
/ 19
9710
/ 3
ICA
, 1 M
CA
, 1
BA, 5
VA
8/10
5/10
5 va
sosp
asm
, 2 C
VA
, di
ssec
tion,
per
fora
tor
occl
usio
n in
2 w
ith C
VA
IV h
epar
in, I
a T
NG
, IA
pap
av, n
imod
ipin
e 9
clin
ical
ly s
tabl
e 2–
30 m
o
ASA
—as
piri
n; B
A—
basa
l art
ery;
CV
A—
cere
brov
ascu
lar
acci
dent
; IA
—in
tra-
arte
rial
; IC
A—
inte
rnal
car
otid
art
ery;
IV—
intr
aven
ous;
LM
W—
low
mol
ecul
ar w
eigh
t; M
CA
—m
iddl
e ce
rebr
al a
rter
y;
PTA
—pe
rcut
aneo
us t
rans
lum
inal
ang
iopl
asty
; SA
H—
suba
rach
noid
hem
orrh
age;
TIA
—tr
ansi
ent
isch
emic
att
ack;
TN
G—
nitr
ogly
ceri
n.
Cerebrovascular Angioplasty and Stenting for the Prevention of Stroke • Chaolupka et al. 47
Mor
i et a
l. [8
5] /
1997
6 / M
CA
(ch
roni
c t
otal
occ
lusi
ons)
4/6
4/6
Non
eA
SA,
hepa
rin
1 re
sten
osis
3 m
o,
no r
este
nose
s in
3
at 3
,4,1
2 m
oM
ori e
t al.
[90]
/ 19
9735
/ 9
ICA
, 20
MC
A,
3 V
A, 1
BA
, 2 P
CA
27/3
5N
ot r
epor
ted
1 sy
mpt
omat
ic
diss
ectio
n, 1
abr
upt
occl
usio
n, 1
ves
sel
rupt
ure
ASA
, LM
W d
extr
an,
hepa
rin,
IA is
osor
bide
8/27
res
teno
sis
at
3 m
o, n
o ch
ange
at
12
mo
Nak
amay
a et
al.
[112
] / 1
998
3 / 3
VA
&BA
3/3
3/3
3 sm
all C
VA
IV h
epar
inA
ll an
giog
raph
ical
ly
pate
nt a
t 3–
6 m
oY
okot
e et
al.
[89]
/ 19
9817
/ 9
ICA
, 4 M
CA
, 4
VA
&BA
16/1
716
/17
1 fa
tal M
CA
dis
sect
ion
Tic
lopi
dien
, IV
hep
arin
3/16
at
3mo,
4/1
6 at
1 y
rM
ori e
t al.
[92]
/ 19
9842
/ 8
ICA
, 21
MC
A,
6 V
A, 5
BA, 2
PC
A33
/42
32/4
2A
brup
t cl
osur
e-C
VA
, di
ssec
tion
CV
AA
SA, L
MW
dex
tran
, he
pari
n, IA
isos
orbi
de
9/32
res
teno
sis
at 1
yEc
kard
et a
l. [1
09]
/ 199
88
/ IC
A7/
87/
81
diss
ectio
n, T
IALo
w M
W d
extr
an,
deca
dron
, ni
mod
ipin
e,
ASA
, he
pari
n
1/7
rest
enos
is
Nom
ura
et a
l. [1
13]
/ 199
96
/ 1 B
A, 5
VA
6/6
6/6
Non
eIV
hep
arin
2 re
sten
oses
at
3
and
4 m
oJim
inez
et a
l. [1
11]
/ 199
91
/ BA
1/1
1/1
Vas
ospa
sm-s
ucce
ssfu
lly
trea
ted
IA u
roki
nase
, IA
ve
rapa
mil,
hep
arin
, IA
pap
aver
ine
Stab
le a
t 7
mo
follo
w-
up
Mar
ks e
t al.
[91•
•] /
1999
23 /
7 IC
A, 3
MC
A,
8 V
A, 4
BA
, 1 P
CA
21/2
321
/23
1 M
CA
rup
ture
-dea
th,
1 ab
rupt
ICA
th
rom
bosi
s-su
cces
sful
ly
sis
IV h
epar
in20
/21
clin
ical
ly
stab
le a
t 16
–74
mo
Con
nors
and
Woj
ack
[7••
] / 1
999
70 /
23 IC
A,
20 M
CA
, 15
VA
, 10
BA
, 2 P
CA
66/7
066
/70
1 C
VA
due
to d
isse
ctio
n,
2 he
mor
rhag
ic s
trok
es,
1 de
ath
due
to a
brup
t oc
clus
ion,
1 d
eath
due
to
ves
sel p
erfo
ratio
n
Abc
ixim
ab, t
iclo
pidi
ne,
ASA
, nim
odip
ine,
he
pari
n
Tab
le 1
.S
um
mar
y o
f clin
ical
rep
ort
s o
f in
trac
ran
ial P
TA
(Co
ntin
ued)
Stu
dy /
year
Ste
nose
s / l
ocat
ion
Tec
hnic
al s
ucce
ssC
linic
al s
ucce
ssC
ompl
icat
ions
Med
icat
ions
Fo
llow
-up
ASA
—as
piri
n; B
A—
basa
l art
ery;
CV
A—
cere
brov
ascu
lar
acci
dent
; IA
—in
tra-
arte
rial
; IC
A—
inte
rnal
car
otid
art
ery;
IV—
intr
aven
ous;
LM
W—
low
mol
ecul
ar w
eigh
t; M
CA
—m
iddl
e ce
rebr
al a
rter
y;
PTA
—pe
rcut
aneo
us t
rans
lum
inal
ang
iopl
asty
; SA
H—
suba
rach
noid
hem
orrh
age;
TIA
—tr
ansi
ent
isch
emic
att
ack;
TN
G—
nitr
ogly
ceri
n.
48 Stroke
Nine (19%) have been placed in the intracranial internalcarotid artery, and 38 (81%) have been placed in theintracranial vertebrobasilar arteries. Ninety-three percenthave been technically and clinically successful. There havebeen four infarcts (two clinically silent), two TIAs, andone procedurally related death. There was one arterialocclusion at 4-months of follow-up. Short-term follow-uphas detected no cases of restenosis.
The University of Iowa Hospitals and Clinics ExperienceRecently, our group has had considerable cumulativeexperience with both extracranial and intracranialcerebral revascularization using endovascular PTA andstenting. In particular, within the past 18 months therehas been a dramatic rise in caseload stemming froma combination of enhanced technical and technologiccapabilities, and an increasing willingness to considerendovascular surgical revascularization in patients withpoor alternative therapeutic options.
In reviewing our last 75 consecutive extracranial carotidPTA and stenting cases, we have achieved the followingshort-term technical and clinical results with the techniquesdescribed earlier. Our technical success rate is 98.7%, inwhich one carotid lesion intended for revascularization hadspontaneously occluded when the patient returned forendovascular stenting after suffering a stroke 4 weeks earlierfrom a nearly occluded ICA. There have been no deaths(0%), major or minor strokes (0%), and only one TIA(1.3%). It must be emphasized that these results have beenachieved without the use of distal protection devicesdesigned to minimize downstream embolization, and allhave undergone third-party adjudication of neurologicoutcomes (as a result of our multidisciplinary effort toprovide this type of endovascular operation) (Fig. 1).
It has previously been noted that extracranialcarotid PTA and stenting (particularly in the ICAbulb region) can be associated with certain cardiovascularcomplications such as bradycardia, hypotension, arrhyth-mia, and myocardial infarction. Although many practi-tioners have expressed significant concern for these typesof complications, the frequency and magnitude of theseproblems remain poorly defined. This led us to retrospec-tively review our case series experience of carotid stenosestreated with PTA and stenting in 75 patients. Our cardio-vascular monitoring routine includes measurement ofheart rate continuously, blood pressure periodically (q 2min), and electrocardiogram (ECG) continuously, before,during, and after PTA and stenting. Prior to endovascularsurgery, patients are evaluated for pre-existing ischemic car-diac disease and arrhythmias by screening history andECG. For patients with suspected coronary occlusivedisease, a stress thalium perfusion study is also obtained,which if positive prompts further work-up by a cardiologist(typically leading to a cardiac catheterization study). In
this case series we avoided prophylactic use of both tempo-rary cardiac pacemakers and pressor infusions. In our lastconsecutive series of 75 PTA and stent operations, majorcardiovascular events occurred only in four cases (5.3%),consisting of persistent hypotension (4%) alone or incombination with persistent bradycardia (1.3%) thatrequired extended hospitalization. One myocardial infarc-tion (1.3%) also occurred in association with persistenthypotension/bradycardia without major sequelae.Although severe bradycardia and hypotension were rarelyencountered in this series, transient or rapidly reversiblehypotension and bradycardia were observed in 40% ofcases. Persistent hypotension and bradycardia in the threecases were treated successfully with either a continuousintravenous infusion of dopamine or intermittent intrave-nous boluses of glycopyrrolate. There were no deaths, andno patient required cardiac pacemaker placement.
Based upon this experience, we believe that clinicallysignificant cardiovascular complications (defined asevents either potentially life-threatening or requiring anextension of hospitalization) are very uncommon, andtypically can be managed medically without the use ofprophylactic pacemaker placement. It is also our impres-sion that cardiovascular complications may be reduced bya combination of pre-emptive measures, includinghypervolemic hydration, glycopyrrolate premedication,and certain technical modifications (eg, slow ballooninflation, avoidance of high inflation pressures, or exces-sive oversizing of self-expanding stents).
Our most recent experience with intracranial PTA andstenting has also been very favorable. In reviewing our last28 consecutive cases, we have achieved the following short-term technical and clinical results using techniques thathave been adapted and modified from those previouslyreported in the literature. Our overall technical successrate is approximately 96%, in which all but one lesionintended for revascularization could not be crossed for PTAor stenting. Our technical success rate specifically forintracranial stenting is slightly lower at 93%. There havebeen no deaths (0%), and only one minor perioperativestroke (3.6%), which was likely related to a hyper-perfusion injury with breakdown of the blood-brain bar-rier. That patient suffered from a chronic, nearly completeocclusion of his left M1 segment of the MCA. He devel-oped a mild right upper extremity paresis and mild expres-sive dysphasia immediately after technically successfulPTA, in which postoperative computed tomographyshowed persistent gyriform enhancement of a portion ofthe frontal lobe. Fortunately, the patient’s deficits com-pletely resolved over a 24-hour period. In our series therealso has been one (3.6%) delayed major stroke occurringin a patient suffering from first a reperfusion hemorrhage 4days after distal ICA stenting, and subsequently a largehemispheric infarction 8 days after stenting. There havebeen no recurrent ipsilateral symptoms in the remainingpatients for variable follow-up intervals of 1 to 16 months.
Cerebrovascular Angioplasty and Stenting for the Prevention of Stroke • Chaolupka et al. 49
Tab
le 2
.S
um
mar
y o
f clin
ical
rep
ort
s o
f in
trac
ran
ial s
tent
ing
Stu
dy /
year
Les
ions
/ lo
cati
onS
tent
sT
echn
ical
su
cces
sC
linic
al
succ
ess
Com
plic
atio
nsM
edic
atio
nsF
ollo
w-u
p
Feld
man
et a
l. [9
3] /
1996
1 / I
CA
Palm
az-S
chat
z1
/ 11
/ 1N
one
ASA
, tic
lopi
dine
, pr
ocar
dia,
hep
arin
No
sign
s at
4 m
o
Dor
ros
et a
l. [9
4] /
1998
1 / I
CA
Palm
az-S
chat
z,1
/ 11
/ 1N
one
Hep
arin
No
sign
s at
5 m
o
Al-M
ubar
ak e
t al.
[95]
/ 19
981
/ IC
AG
iant
e R
oubi
n-2
1 / 1
1 / 1
Non
eN
one
No
sign
s at
4 m
o
Phat
ouro
s et
al.
[96]
/ 19
991
/ BA
Gia
nte
Rou
bin-
21
/ 11
/ 1D
eath
due
to
seps
is/
card
ioge
nic
shoc
kH
epar
in, I
A u
roki
nase
Dea
th o
n po
st-s
tent
day
10
Mor
i et a
l. [9
7] /
1999
1 / V
AG
FX1
/ 11
/ 1N
one
LMW
dex
tran
, hep
arin
, IA
isos
orbi
deN
one
Lanz
ino
et a
l. [9
8] /
1999
1 / B
AG
FX1
/ 11
/ 1N
one
IA u
roki
nase
, hep
arin
No
sign
s at
5 m
o
Fess
ler
et a
l. [9
9] /
1999
1 / I
CA
GFX
1 / 1
1 / 1
2 cl
inic
ally
sile
nt e
mbo
lic C
VA
Hep
arin
, IA
NT
G,
IA u
roki
nase
Stab
le a
t 5
mo
Mal
ek e
t al.
[100
] / 1
999
1 / V
BAG
FX1
/ 11
/ 1St
ent-
indu
ced
diss
ectio
n,
brai
nste
m C
VA
Hep
arin
, clo
pido
grel
, ASA
Impr
oved
at
5 m
o,
min
imal
hem
ipar
esis
Hor
owitz
et a
l. [1
02]
/ 199
93
/ BA
GFX
, M
ultil
ink
3 / 3
3 / 3
Pont
ine
infa
rct,
tran
shem
ipar
esis
ASA
, clo
pido
grel
, hep
arin
, IA
uro
kina
se, a
bcix
imab
Non
e
Mor
ris
et a
l. [1
01]
/ 199
93
/ 1 IC
A,
2 V
AG
FX3
/ 33
/ 3N
one
ASA
, clo
pido
grel
, he
pari
n, a
bcix
imab
No
rest
enos
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50 Stroke
One (3.6%) angiographic restenosis has been thus fardetected in a patient undergoing intracranial PTA alone.
ConclusionsDramatic technical and technologic innovations are likelyto occur as operators gain more experience and insight intothe best ways to more safely and effectively revascularizethe cerebrovascular system using endovascular surgery. Theimmediate effects of this cumulating experience will be inthe continuing refinement and standardization of existingconventional percutaneous transarterial access and revas-cularization applied specifically to the cerebrovascularsystem. This may sound like a modest goal to aspire to,however, as noted earlier, there has been a considerable lagin properly defining the best technical and technologicparameters for cerebrovascular PTA and stenting. Theseparameters first will have to be clearly defined and articu-lated in a way that will eventually permit their validation
through the technical and clinical outcomes achieved infuture reports of case series experience.
Future enhancements also will be particularly depen-dent upon technologic innovation, largely owing tothe medical device industry’s recent realization of thesubstantial economic implications of this emerginghealth-care market. Newer PTA and stent devices willlikely be more streamlined and flexible, permitting saferand more reliable delivery into the cerebrovascular sys-tem. Adjunctive downstream embolic protection deviceswill become widely utilized. Advances in material scienceand engineering will permit construction of stentswith superior mechanical properties and biocompatibilitythat may overcome many of the current problems andlimitations of these devices. With our ever increasingunderstanding of the cellular and molecular basisof vascular biology, we predict that stent coating withvarious biologically active molecules (eg, growth factors,cytokines, recombinant constructs) will be commonly
Figure 1. An 83-year-old white male presented with a 14-day history of intermittent slurred speech, light-headedness, and right facial droop. Magnetic resonance imaging revealed chronic ischemia of the cerebellar hemispheres, occipital lobes, and right pons. A, Right vertebral angiogram revealed a 10-mm long 75% stenosis of the V4-5 segments (arrow). B, Using a micro-guidewire, a balloon-mounted, 3.5 mm x 12 mm AVE GFX stent was placed across the stenosis. C, The stent was deployed by inflating the balloon to 9 atm. D, An agniogram following angioplasty and stent placement revealed no significant residual stenosis of the vertebral artery (arrows).
Cerebrovascular Angioplasty and Stenting for the Prevention of Stroke • Chaloupka et al. 51
employed to promote a more controlled and predictableneointimalization, and possibly to stimulate beneficialarterial wall remodeling. It is also likely that novel techno-logic innovation will bring to clinical practice manyunconventional tools such as self-navigating catheters,angioscopy, endovascular atherectomy devices, and bio-logically active thin-film covered stents, all of which willexpand the capabilities and indications of endovascularsurgical management of cerebrovascular occlusive disease.
Finally, with its increasing capabilities, various endo-vascular surgical revascularization techniques will likelybe considered more routinely (albeit probably initiallyreluctantly) as a primary therapeutic modality for strokeprevention. This is likely because of a lack of promisingprimary pharmacologic interventions, and the overalltrend in all surgical disciplines towards more minimallyinvasive therapies. However, for this to occur, far morerigorous scientific evaluation of both short-term and long-term efficacy of cerebrovascular PTA and stenting will beneeded, including the need for multicenter, randomized,clinical trials designed to evaluate either equivalency orsuperior efficacy to conventional interventions.
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