Cerebral protection during carotid artery stenting: collection and histopathologic analysis of embolized debris

Magnetic resonance plaque imaging to predict the occurrence of the slow-flow phenomenon in carotid artery stenting procedures

INTRODUCTION

The purpose is to investigate the feasibility of magnetic resonance (MR) plaque imaging in predicting the arterial flow impairment (slow-flow phenomenon) during carotid artery stenting (CAS) using a filter-type protection device.

METHODS

Thirty-one carotid artery stenotic lesions in 30 patients (28 men and two women; mean age, 71.8 years) were evaluated by MR plaque imaging with black blood T1- and T2-weighted and time-of-flight sequences before CAS. Main plaque components were classified as vulnerable (intraplaque hemorrhage and lipid-rich/necrotic core) or stable (fibrous tissue and dense calcification) from the signal pattern. The plaque classification was statistically compared with the occurrence of slow-flow phenomenon.

RESULTS

The slow-flow phenomenon was observed in ten CAS procedures (five flow arrests and five flow reductions). Flow arrests consisted of four vulnerable and one stable plaque, and flow reductions consisted of four vulnerable and one stable plaque. The slow-flow phenomenon occurred significantly (P<0.01) more frequently in patients with vulnerable plaque.

CONCLUSIONS

Vulnerable carotid plaques have a significantly higher risk of slow-flow phenomenon than stable plaques. The occurrence of the slow-flow phenomenon can be predicted by MR plaque imaging before CAS.

V, Karakhanian WK, Caffaro RA. Técnica para quantificação e qualificação de material coletado em filtros de proteção cerebral

Contexto: A qualidade e a quantidade de partículas coletadas em filtros de proteção cerebral (FPC) durante angioplastia transluminal percutânea com stent (ATPS) podem esclarecer a importância desses dispositivos no tratamento de estenoses carotídeas. Objetivos: Analisar o conteúdo retido por FPC em pacientes submetidos a ATPS de artéria carótida interna com nova técnica de análise qualiquantitativa. Métodos: O material coletado em 10 FPC durante ATPS da bifurcação da carótida em pacientes com alto risco cirúrgico foi submetido a análise microscópica qualiquantitativa. Fotografias digitais das lâminas com material corado com hematoxilina e eosina foram analisadas com o programa Axio Vision LE Release 4.1, que calculou a área das partículas em micrômetros/metro quadrado (µm²). Resultados: O exame histopatológico evidenciou material em 100% dos filtros consistindo predominantemente de restos hemáticos, cristais de colesterol e cálcio. A área média de fragmentos coletados foi expressiva (1.570.310 µm²), e houve ampla variância desses valores. Conclusões: Os FPC coletam quantidade importante de fragmentos de placas de ateroma, e a grande variância nas quantidades de material coletado pode estar associada com a gravidade da lesão, motivo pelo qual se tornam relevantes estudos que utilizem técnica padronizada para a quantificação desses fragmentos e para a compreensão de seu real significado clínico.

Observation of the embolus protection filter for Carotid Artery Stenting

BACKGROUND

Carotid artery stenting in patients with high surgical risk is considered as an effective alternative to carotid endarterectomy. Because the occurrence of distal embolization with CAS is still a major concern, an embolus protection device is usually used during the procedure. We developed a technique for observation of embolus protection filter and evaluated the debris or thrombus microscopically, and the pathologic findings were compared with preoperative imaging studies.

METHODS

After completing CAS, the filter membrane was stained with HE solution and removed from filter strut. Mounting onto a glass slide, the filter was evaluated under a microscope. Plaque debris and appearance of filter membrane were evaluated, and the covered area was measured. The pathologic findings were compared with preoperative imaging studies.

RESULTS

Microscopic observation of the slide revealed atheromatous debris as well as thrombotic material to the filter membrane. Hematoxylin-eosin stain facilitates the characterization of the debris composition, namely, thrombotic debris, calcified debris, organized debris, fibrous debris, and lipid-rich debris. The subtypes of debris were consistent with preoperative imaging studies. Thus, in cases of intraprocedural flow impairment, more than 50% of the filter area was covered with debris or thrombotic material.

CONCLUSION

Carotid plaque debris captured during carotid stenting with protection filter can be visualized with HE stain on the glass side. This simple method allows us to better understand the plaque debris and appearance of embolus protection filter.

Volume and composition of emboli in neuroprotected stenting of the carotid artery

BACKGROUND AND PURPOSE

Periprocedural microembolization is a major and permanent risk for patients treated by angioplasty and stent placement of high-grade carotid stenoses. Little is known however about the characteristics and significance of these embolized particles. Our aim was to assess the volume and composition of debris captured by filters during carotid angioplasty and stent placement (CAS) of severe internal carotid artery (ICA) stenoses.

MATERIALS AND METHODS

Institutional review board approval and informed consent from all subjects were obtained. Two hundred one patients (mean age, 66.2 years; range, 35-82 years) with > or = 70% stenosis of the ICA underwent filter-protected CAS. Ultrastructural and semiquantitative analysis of the volume of filters was obtained. Multifactorial statistical analysis was performed to determine factors related to debris volume and composition.

RESULTS

Transient ischemic attack occurred in 6 patients (3%), and a major stroke, in 1 (0.5%). Debris was found in 117 filters (58.2%), with volume <1 lambda (0.001 mL) in 71%. The number of balloon dilations, age older than 65 years, and calcified plaques in pre-CAS angiography were significantly associated with the presence of particulates inside the filters (P < .03, P < .004, and P < .05, respectively).

CONCLUSIONS

Vessel wall and atheromatous plaques are the main source of microemboli during CAS. Embolization is mainly related to the number of balloon dilations during CAS. Planning a proper and individualized strategy for the procedure in each patient is essential to minimize the potential effects of manipulation during CAS.

Microscopic and macroscopic evaluation of emboli captured during angioplasty and stent procedures in extracranial vertebral and internal carotid arteries

PURPOSE

To compare the quantities of emboli dislodged during percutaneous transluminal angioplasty/stenting in the vertebral artery (VA) with those released during stent placement in the internal carotid artery (ICA).

METHODS

Macroscopic images of distal protection devices (DPD) used during 30 stent procedures in 16 ICAs (11 men; mean age 64.6+/-10.6 years) and 14 VAs (9 men; mean age 67.1+/-9.8 years) were reviewed. The amount of captured embolic debris was calculated and expressed as a proportion to the size of the filter. Histological examinations were performed to characterize the material trapped in the filters.

RESULTS

Relative to the size of the filter, the proportion of captured debris ranged from 0.1% to approximately 22% in the ostial VA filters and from 0.1% to approximately 21% in the filters used in the ICA procedures (p = NS). Plaque fragments with or without thrombus were discovered in the histological examinations of captured material. There were no significant differences in the characteristics of the debris between the 2 vascular regions, nor did sex, race, or plaque morphology correlate significantly with the proportion of captured debris. However, the severity of stenosis was significantly (p<0.029) greater in the ICA (73%+/-0.11%) than the VA (63%+/-0.09%) territory.

CONCLUSION

The study suggests that the frequency and amount of captured emboli during stent procedures in ICA and ostial VAs are comparable. Therefore, the use of a DPD for stent placement in the vertebral artery may be advisable.

Initial experience of using the filter protection device during carotid artery stenting in Japan

PURPOSE

No filter protection devices for carotid artery stenting (CAS) have been formally approved for use in Japan; however, as of April 2008, the Angioguard XP (AGXP) was approved. This article describes our initial results using the AGXP during CAS for the treatment of carotid artery stenosis.

MATERIAL AND METHODS

A group of 15 patients (14 men) with a mean age of 72.3 years (range 53-81 years) were treated by CAS using the AGXP. Among them, 10 were symptomatic with >50% stenosis of the common or internal carotid artery (ICA), and 5 were asymptomatic with >70% stenosis. The rates of technical success, periprocedural stroke, ICA flow impairment, filter movement, and development of new ischemic lesions on diffusion-weighted imaging (DWI) were assessed.

RESULTS

CAS using the AGXP was successful in all cases. There was one minor stroke, and flow impairment occurred in six patients. Filter movement averaged 1.9 vertebral bodies. DWI showed new ipsilateral ischemic lesions in eight of the patients.

CONCLUSION

Initial clinical experience using the AGXP for CAS has been generally sufficient. However, attention must be paid to three problems when using the AGXP: the filter may move after placement; the filter may disturb blood flow in the ICA; and debris may pass around the filter.

Flow impairment during protected carotid artery stenting: impact of filter device design

PURPOSE

To investigate the impact of filter design on blood flow impairment in the internal carotid artery (ICA) among patients undergoing carotid artery stenting (CAS) using filter-type emboli protection devices (EPD).

METHODS

Between July 2003 and March 2007, 115 filter-protected CAS procedures were performed at an academic institution in 107 consecutive patients (78 men; mean age 68 years, range 38-87). The Angioguard, FilterWire EZ, and Spider filters were used in 68 (59%), 32 (28%), and 15 (13%) of cases, respectively. Patient characteristics, procedural and angiographic data, and outcomes were prospectively entered into an electronic database and reviewed retrospectively along with all angiograms.

RESULTS

Flow impairment while the filter was in place was observed in 25 (22%) cases. The presumptive reason of flow impairment was filter obstruction in 21 (18%) instances and flow-limiting spasm at the level of the filter in 4 (4%). In all cases, flow was restored after retrieval of the filter. Flow obstruction in the ICA occurred more frequently with Angioguard (22/68; 32.3%) than with FilterWire EZ (2/32; 6.2%) or Spider (1/15; 6.7%; p = 0.004). No flow occurred in 13 (19%) procedures, all of them protected with Angioguard; no patient treated with other devices experienced this event (p = 0.007). Two (8.0%) strokes occurred in procedures associated with flow impairment, while 1 (1.1%) event was observed in the presence of preserved flow throughout the intervention (p = 0.11).

CONCLUSION

Flow impairment in the ICA during filter-based CAS is common and related to the type of filter used.

Cerebral ischemia detected with diffusion-weighted MR imaging after protected carotid artery stenting: comparison of distal balloon and filter device

Objective

The aim of this study was to examine the incidence of ischemia during protected carotid artery stenting (CAS) as well as to compare the protective efficacy of the balloon and filter devices on diffusion-weighted MR imaging (DWI).

Materials and Methods

Seventy-one consecutive protected CAS procedures in 70 patients with a severe (> 70%) or symptomatic moderate (> 50%) carotid artery stenosis were examined. A balloon device (PercuSurge GuardWire) and a filter device (FilterWire EX/EZ, Emboshield) was used in 33 cases (CAS-B group) and 38 cases (CAS-F group) to prevent distal embolization, respectively. All the patients underwent DWI within seven days before and after the procedures. The number of new cerebral ischemic lesions on the post-procedural DWI were counted and divided into ipsilateral and contralateral lesions according to the relationship with the stenting side.

Results

New cerebral ischemic lesions were detected in 13 (39.4%) out of the 33 CAS-Bs and in 15 (39.5%) out of the 38 CAS-Fs. The mean number of total, ipsilateral and contralateral new cerebral ischemic lesion was 2.39, 1.67 and 0.73 in the CAS-B group and 2.11, 1.32 and 0.79 in the CAS-F group, respectively. No statistical differences were found between the two groups (p = 0.96, 0.74 and 0.65, respectively). The embolic complications encountered included two retinal infarctions and one hemiparesis in the CAS-B group (9.09%), and one retinal infarction, one hemiparesis and one ataxia in the CAS-F group (7.89%). There was a similar incidence of embolic complications in the two groups (p = 1.00).

Conclusion

The type of distal protection device used such as a balloon and filter does not affect the incidence of cerebral embolization after protected CAS.

Treatment of cholesterol crystal embolisation syndrome with filter-assisted stenting

A 70-year-old man with acutely painful fingertips on the left hand, with ulceration and necrosis of the second and fourth fingertip, was referred to our centre for evaluation. Crystal cholesterol embolisation (CCE) from the left subclavian artery plaque was suspected on the basis on a normal brachial pulse. A selective arteriography confirmed the presence of mild (60%) subclavian stenosis and suggested the need for filter-assisted stenting of the subclavian artery to prevent CCE. The vessel was hooked with a right coronary curve 8-Fr guiding catheter and the lesion crossed with an Angioguard filter (Cordis, J&J Medical, Warren, New York, USA), 8 mm in diameter, open distally to the stenosis. A 6 mm x 18 mm balloon expandable Genesis stent (Cordis, J&J Medical, Miami Lakes, Florida, USA) was successfully deployed at a pressure of 12 atm, with good angiographic result. Macroscopic lipidic material was visible in the filter after retrieval and microscopic analysis confirmed the presence of cholesterol crystals. The patient was symptom-free with healing of the fingertips on follow-up, suggesting that CCE may be safely and effectively treated with filter-assisted angioplasty.

Particulate debris collected during carotid stenting: are we missing something?

Particulate and histopathologic examination of atherosclerotic material collected during carotid artery stenting is presented, illustrating the limitations of current knowledge regarding the use of distal protection devices (DPD) during this novel vascular intervention.

Exclusion of Atherosclerotic Plaque from the Circulation Using Stent-Grafts: Alternative to Carotid Stenting with a Protection Device?

PURPOSE

To retrospectively assess the feasibility, safety, and clinical mid-term outcome of patients undergoing carotid artery stenting with stent-grafts.

METHODS

Over a 4 year period stent-grafts were used in the endovascular treatment of symptomatic internal carotid artery stenosis in 12 patients (2 women, 10 men, aged 47-83 (mean 64) years). Protection devices were not used. Possible microembolic complications were evaluated by magnetic resonance imaging (MRI) examinations of the brain before and the day after the procedure in all patients. Mean follow-up was 22 months (range 1-42 months), by Doppler ultrasonography and conventional angiography as well as clinical examination.

RESULTS

The technical success rate was 100%. A total of 13 coronary stent-grafts were used. The mean stenosis rate (in terms of diameter) was 85% and the mean length of stent-grafts used was 20.9 mm. The mean diameter to which the stent-grafts were dilated was 4.66 mm. In-hospital complications occurred in 1 patient who suffered a minor femoral access hematoma that did not require transfusion or surgical decompression. Post-stenting diffusion-weighted MRI revealed several ipsilateral silent microemboli in only 1 case, which was completely asymptomatic. Two patients had a major stroke after 2 years of follow-up. Restenosis was found in 2 patients who underwent successful balloon dilatation followed by placement of a self-expandable bare stent within the stent-grafts.

CONCLUSIONS

Stent-grafts may prevent microembolic complications during stenting of atherosclerotic carotid lesions in selected cases, offering immediate exclusion of the atherosclerotic lesion from the circulation by pressing the plaque against the vessel wall. Comparative, randomized studies in larger series of patients are needed with carotid-dedicated stent-graft designs.

Determining the quantity and character of carotid artery embolic debris by electron microscopy and energy dispersive spectroscopy

OBJECTIVES

Carotid artery angioplasty and stenting (CAS) is now routinely performed with embolic protection devices, yet little is known about the compositional characteristics of the captured embolic debris and whether the type or quantity of debris correlates with patient, lesion, or operator characteristics. This study examined the embolic debris generated during CAS using electron microscopy and energy dispersive spectroscopy (EDS) for symptomatic and asymptomatic patients.

METHODS

Between 2003 and 2005, CAS for carotid stenosis was performed in 175 patients. Cerebral protection devices were used in all but three cases. Sixty-four consecutive unselected microporous filters from procedures performed by a single vascular surgeon were obtained for analysis. Captured particulate debris within the protection devices was quantified (number and mean size of particles) by light microscopy for all filters. Twenty protection devices (9 symptomatic, 11 asymptomatic patients) were processed for electron microscopy and EDS to assess morphology, cellular composition, and calcium content of debris.

RESULTS

Captured particulate matter was present in 49 filters (77%) and included particles measuring 200 to 500 mum in 72%, 500 to 1000 mum in 53%, and >1000 mum in 33%. The mean number of captured particles was 6.9, and mean size was 248 +/- 150 mum. Univariate analysis revealed that sequential patient cohort and filter type were correlated with the number (but not size) of captured particles. The number of particles significantly decreased after the first cohort of 20 patients (11.5 particles) compared with the second (5.0 particles, P = .023) and third (5.2 particles, P = .029) cohorts. The type of captured debris ranged from sheets of damaged red blood cells without other components to clumps of recently activated platelets with early fibrin crosslinking to plaque debris coated with well-organized coalescing areas of platelet thrombus. Platelet activation was more common in symptomatic patients (78%) than asymptomatic patients (27%; P < .05). Despite the presence of calcified lesions in six patients whose filters were analyzed by EDS, <1% of energy emission on EDS of scanned particulate debris fell within the emission range of calcium, indicating the presence of minimal calcium in the embolic particles.

CONCLUSIONS

Particulate embolic debris is released in most patients during CAS and can measure >1000 mum in one third of patients. The number of particles may decrease with increasing operator experience with CAS. Debris captured during CAS with embolic protection exhibits a range of cellular and acellular components on electron microscopy, with a higher prevalence of platelet activation evident in symptomatic patients.

Protected carotid stenting: the usefulness of filter protection devices

We report our experience in carotid artery stenting using a filter protection device. From July 2003 to September 2006 we treated 62 patients by internal carotid stenting using a filter protection device. Procedural success was achieved in 100% of cases. There were five periprocedural complications: one dissection of the internal carotid artery, two TIAs and two groin haematomas at the site of needle access. Neurological examination performed after the procedure and during the 30 days of follow-up did not reveal major neurological complications. Cerebral protection with a filter during carotid artery stenting seemed feasible and safe.

Double-Wire Technique in Balloon-Protected Carotid Artery Stenting

OBJECTIVES

To evaluate the safety and efficacy of a double-wire technique in carotid artery stenting (CAS) with a distal occlusion balloon system, PercuSurge GuardWire.

METHODS

Fifty-one consecutive patients with 53 de novo lesions were scheduled to undergo balloon-protected CAS with the "double-wire technique," the use of two wires, one for independent predilatation and the other for stent implantation.

RESULTS

Fifty consecutive patients underwent a total of 52 balloon-protected CAS except for 1 patient with one lesion that could not be accessed. The use of a 1.5-mm coronary balloon was necessary in only 2 cases (3.8%) to let the PercuSurge GuardWire cross critically stenotic lesions. The placement of the PercuSurge GuardWire into the internal carotid artery was successful in all cases. Technical success was obtained in all cases. Fifty lesions (96.2%) were treated with one inflation of the distal occlusion balloon during the entire procedure consisting of predilatation, stent implantation, and aspiration, and among them three lesions (5.8%) required postdilatation. The mean occlusion time of cerebral blood flow for 50 lesions was 266 +/- 37 seconds. Out of 50 procedures, 45 (90.0%) had occlusion times of 300 seconds or less. Neurological intolerance requiring intravenous anesthesia was seen in 4 cases (7.7%) and periprocedural neurological complication in 2 cases (3.8%).

CONCLUSIONS

The "double-wire technique" is safe and effective for the shortening of occlusion time during predilatation, stent implantation, and aspiration, leading to satisfactory technical and clinical outcomes, in most cases. This technique should be considered for balloon-protected CAS using the PercuSurge GuardWire.

New distal embolic protection device the FiberNet® 3 dimensional filter: First carotid human study

OBJECTIVE

Evaluate the performance and safety of the FiberNet Embolic Protection System during carotid artery intervention.

BACKGROUND

Carotid Angioplasty and Stenting (CAS) can be proposed to treat the majority of carotid stenoses. Brain embolization takes place and routine use of Embolic Protection Devices (EPD) is warranted. Many EPDs have significant limitations, which may be addressed by a new EPD, the FiberNet (Lumen Biomedical, Plymouth, MN).

METHODS

The system consists of a 3-dimensional expandable filter made of fibers, which expand radially, mounted onto a 0.014'' wire and retrieval catheter. FiberNet can capture particles as small as 40 microm without compromising flow.

RESULTS

35 lesions treated in 34 patients. Male 67.6%. Age: 71.4 +/- 8.8 (50-85). Average stenosis 84.5% +/- 7.9 (70-99). 29.4% were symptomatic. Technical success: 34/35 (97%). No stroke or death within 30 days. Neurological events: two permanent amaurosis, one amaurosis fugax. All samples visually contained significant amounts of emboli. The mean surface area of debris caught was 63.8 mm(2) (37.7-107.5). Comparisons were made with other EPDs. The mean surface area of debris caught was 12.2 mm(2) (2.7-34.3). No changes were noted in CT/MRI at 30-day post procedure.

CONCLUSION

The first human use of this new novel EPD in carotid artery stenting is encouraging. The FiberNet was easy to use and confirmed the ability to capture particles less than 100 microm. The feasibility of the FiberNet has been demonstrated. Additional patients will demonstrate the overall safety and efficacy of this new EPD device.

Distal embolism during percutaneous revascularization of infra-aortic arterial occlusive disease: an underestimated phenomenon

PURPOSE

To investigate distal embolism during endovascular procedures of the infra-aortic arteries by utilizing a commercial filter basket and unveil any correlation between the baseline clinical and procedural variables and the histopathological findings of the collected particles.

METHODS

In a prospective study, 48 patients (37 men; mean age 70.8+/-7.8 years, range 50- 83) underwent endoluminal therapy of infra-aortic lesions (stenosis >75% or occlusion; mean lesion length 52.2+/-38.0 mm) with standard endovascular procedures. A nitinol filter basket (n=50) was employed for distal protection. The collected particles were histopathologically analyzed. The harvested specimens were quantified after digital image post processing.

RESULTS

Procedural success of filter-protected revascularization was 93.8%. Three failures included 1 vasospasm, 1 distal embolus, and 1 side-branch occlusion. The total area of retrieved particles per basket was 2.76+/-6.49 mm(2) (range 0.0-40.3). Particles with a major axis >1 and >3 mm were detected in 29 (58.0%) and 6 (12.0%), respectively, of the examined filters. Collected particles consisted primarily of platelets and fibrin conglomerates, trapped erythrocytes, inflammatory cells, and extracellular matrix. Increased lesion length, increased reference vessel diameter, acute thromboses, and total occlusions were positively correlated with higher amounts of captured particles (p<0.05). Multivariate analysis incriminated declotting procedures as the only independent predictor of increased embolic burden (p<0.05).

CONCLUSION

The embolism phenomenon during infra-aortic interventions is frequent and underestimated. The liberated particles consisted primarily of atheromatous plaque elements and thrombus. The reported data might support the application of a protective filter basket in selected subsets of lesions with a riskier embolic profile and whenever declotting procedures are performed.

Endovascular Treatment of In-Stent Restenosis After Carotid Artery Stenting: Immediate and Midterm Results

PURPOSE

To evaluate the immediate and midterm outcome and analyze the debris captured after repeat endovascular intervention for the treatment of in-stent restenosis after carotid artery stenting (CAS).

METHODS

Thirty-one consecutive patients (27 men; mean age 63.7+/-13.0 years, range 53- 81) underwent repeat endovascular intervention (balloon angioplasty and provisional stenting) for the treatment of 32 in-stent restenoses following CAS.

RESULTS

Procedural success was achieved in all patients. An additional stent was implanted in 10 (31%) cases. No procedural complication was observed. Filter analysis was performed in 17 (53%) procedures; on 12 (71%), macroscopically visible material was captured. The histomorphometric analysis performed on 6 (19%) filters showed fibrin nets entrapping erythrocytes, leucocytes, platelets, and in 2 cases, fibrous hypercellular tissue fragments. At 30 days and during follow-up (mean 17+/-5 months), no deaths, transient ischemic attacks, or strokes were observed. In 1 (3.1%) patient, asymptomatic recurrence of ISR was found on Doppler ultrasonography and successfully treated with balloon angioplasty.

CONCLUSION

Repeat endovascular intervention using balloon angioplasty with provisional stenting and routine cerebral protection appears to be a feasible, safe, and clinically effective strategy for the treatment of in-stent restenosis after CAS.

Embolic protection filters for carotid stenting: differences in flow obstruction depending on filter construction

PURPOSE

To investigate the pressure gradient and degree of flow reduction associated with embolus protection filters for carotid stenting in an in vitro experiment.

METHODS

Three filter devices with a perforated membrane design and one wire mesh type filter were tested. At a pressure of 70 mmHg, the flow reduction and pressure gradient were measured in a 5-mm tube using blood-mimicking fluid.

RESULTS

The pressure gradient in the wire mesh filter was 1.65+/-0.49 mmHg (95% CI 1.32 to 1.86). The mean pressure gradient in the perforated membrane filters was 6.88+/-2.62 mmHg (95% CI 6.22 to 7.55, p<0.0001). There was also a significant correlation between pressure gradient and flow reduction (r=-0.77, p<0.01).

CONCLUSION

Embolic protection filters cause a pressure gradient and obstruct blood flow. This effect is marked in perforated membrane filters and almost absent in the wire mesh filter.

Assessment of short-term outcomes for protected carotid angioplasty with stents using recent evidence

BACKGROUND

Carotid artery stenosis is an important risk factor and etiology of stroke. Carotid endarterectomy (CEA) is the gold standard for the treatment of carotid artery stenosis; however, there are potential benefits to adopting the use of carotid artery stenting (CAS) with protection devices. A number of large protected CAS (PCAS) trials are underway, but final results are still several years away. In the interim, numerous PCAS studies have recently been published, and the aim of this study was to combine the published results and examine the outcomes and safety of PCAS.

METHODS

Electronic, manual, and bibliographic searches of PubMed and PreMedline were conducted. Proportion differences were calculated for the periprocedural (30-day) outcomes of any stroke and any stroke or death.

RESULTS

More than 400 articles were identified. Only 26 studies met the inclusion criteria, resulting in the inclusion of 2,992 patients treated with PCAS. Within this patient group, the pooled perioperative PCAS rate of any type of stroke was 2.4% +/- 0.3% (95% confidence interval [CI]). The 30-day minor stroke rate was 1.1% +/- 0.2% (95% CI), and the 30-day major stroke rate was 0.6% +/- 0.2% (95% CI). The 30-day mortality rate was 0.9% +/- 0.4% (95% CI).

CONCLUSION

This study demonstrates relatively low rates of reported perioperative adverse events in PCAS. Selective use of PCAS to treat carotid artery stenosis in those at highest risk for surgical complications is appropriate until the randomized trials of CEA vs PCAS provide concurrent short- and long-term outcome data.

Feasibility Trial of Carotid Stenting With and Without an Embolus Protection Device

PURPOSE

To evaluate the feasibility of stenting and cerebral protection in patients with carotid bifurcation disease.

METHODS

Carotid stenting with self-expanding nitinol stents was evaluated in 261 patients (157 men; mean age 70.9+/-9.7 years, range 41-90) treated at 33 clinical sites. Among these patients, 141 (54.3%) were symptomatic, and 71 (27.2%) had postendarterectomy restenotic lesions. An embolus protection device became available in the latter third of the study. The primary endpoint of the study was the 30-day composite occurrence of major adverse clinical events (all deaths, strokes, or myocardial infarctions [MI]). At 1 year, the endpoint included all deaths, strokes, or MIs at 30 days, plus all deaths or ipsilateral strokes between 31 days and 1 year.

RESULTS

SMART stents were placed in 147 (56%) patients and Precise stents in 107 (41%); 7 (3%) patients were treated with non-study stents. Lesion success, defined as <30% postprocedural residual stenosis, was achieved in 249 (95%). An AngioGuard filter was used in 85 patients; of 90 filters employed, 78 (87%) were successfully deployed and retrieved. Visible material was noted in 42 (54%) retrieved filters. One (0.4%) stent thrombosis occurred at <30 days, and no restenotic lesions >80% were noted in up to 1 year of follow-up. At 30 days, stroke occurred in 16 (6.1%) patients, MI in 1 (0.4%), and 2 (0.8%) patients died. The 30-day rate of stroke, MI, or death was 6.9%. Major ipsilateral stroke occurred in 4 (1.5%) patients between 0 and 30 days; no new major ipsilateral strokes were noted up to 1 year. By Kaplan-Meier analysis, the 1-year risk of stroke, MI, or death was 10.9%+/-2.0%. The 1-year risk of major ipsilateral stroke was significantly lower in patients treated with embolus protection devices (0.0% versus 2.3%, p=0.05).

CONCLUSIONS

The use of nitinol self-expanding stents in the carotid position appears to be a safe and efficacious alternative for the treatment of carotid bifurcation disease. The addition of embolus protection devices may diminish the risk of postprocedural major ipsilateral strokes.

Procedure-Related Complications and Early Neurological Adverse Events of Unprotected and Protected Carotid Stenting:Temporal Trends in a Consecutive Patient Series

PURPOSE

To report procedure-related complications and neurological adverse events of unprotected over-the-wire (OTW) and protected rapid exchange (RX) carotid artery stenting (CAS) in a single-center patient series during an 8-year period.

METHODS

Between 1997 and 2004, 651 consecutive patients (445 men; median age 72 years, interquartile range 64-77) were enrolled in a registry database of carotid stent procedures; from 1997 to 2002, 471 patients underwent unprotected CAS using an OTW technique, while the other 180 patients were treated with protected CAS using RX monorail systems from 2003 to 2004. Technical success and complications (neurological, hemodynamic instability, and access site) up to 30 days post intervention were analyzed.

RESULTS

Technical success improved from 95% with unprotected OTW CAS to 99% with protected RX CAS (p=0.025). Procedure-related complications occurred in 86 (18.3%) of 471 unprotected OTW CAS versus 18 (10.0%) of 180 protected RX CAS procedures (p=0.010). Transient ischemic attacks (3.2% versus 2.8%), minor stroke (1.7% versus 0.6%), and major stroke (2.1% versus 0.6%) showed a trend toward a difference between unprotected OTW and protected RX CAS (p=0.076); combined 30-day stroke/death rates were 3.8% for OTW versus 1.2% for RX CAS (p=0.073). During the 8-year period from 1997 to 2004, the annual rates of procedure-related complications (p=0.002), neurological events (p=0.040), and stroke and death (p=0.14) markedly decreased.

CONCLUSIONS

Carotid stenting became substantially safer in the era of protected RX technology. In addition to a reduction in neurological complications, which may be due to cerebral protection devices, the improved technical success and reduced non-neurological procedure-related complications are likely due to recent technical advances unrelated to cerebral protection.

Slow-flow phenomenon during carotid artery intervention with embolic protection devices: predictors and clinical outcome

OBJECTIVES

The purpose of this research was to define the predictors of the "slow-reflow" phenomenon during carotid artery intervention with filter-type embolic protection devices (EPDs) and to determine its prognostic significance.

BACKGROUND

During carotid artery intervention using filter-type EPDs, we have observed cases in which there is angiographic evidence of a significant reduction in antegrade flow in the internal carotid artery proximal to the filter device, termed "slow-flow." The predictors of this phenomenon and its prognostic significance are unknown.

METHODS

Using a single-center prospective carotid intervention registry, patients with slow-flow were compared to patients with normal flow during carotid intervention with respect to clinical, procedural, and lesion characteristics, and the 30-day incidence of death and stroke.

RESULTS

A total of 414 patients underwent 453 carotid artery interventions using EPDs. Slow-flow occurred in 42 patients (10.1%) undergoing 42 carotid interventions (9.3%), and most commonly occurred after post-stent balloon dilatation (71.4%). Multivariate logistic regression analysis identified the following predictors of slow-flow: recent history (<6 months) of stroke or transient ischemic attack (odds ratio [OR] 2.8, 95% confidence interval [CI] 1.4 to 5.6, p = 0.004), increased stent diameter (OR 1.4, 95% CI 1.02 to 1.94, p = 0.044), and increased patient age (OR 1.05, 95% CI 1.01 to 1.09, p = 0.025). Among patients with slow-flow, the 30-day incidence of stroke or death was 9.5% compared to 2.9% in patients with normal flow (chi-square = 4.73, p = 0.03). This difference was driven by the disparity in the 30-day incidence of stroke (9.5% vs. 1.7%).

CONCLUSIONS

Slow-flow during carotid intervention with EPDs is a frequent event that is associated with an excess risk of periprocedural stroke. The association of the phenomenon with clinically symptomatic carotid lesions and use of larger stent diameters suggests that embolization of vulnerable plaque elements may play a pathogenic role.

Observing the carotid debris aspirated during carotid stenting: technical note

OBJECTIVES

Elective carotid stent implantation using a distal protection is increasing. In this article we describe an observation method for carotid plaque debris collection during carotid stenting.

METHODS

Endovascular stenting for the right internal carotid artery (ICA) stenosis was performed under distal balloon protection. During balloon protection, 30 ml of blood containing debris was aspirated followed by vigorous saline irrigation flushing any residual debris out into the ipsilateral external carotid circulation. Post-operatively, the aspirated blood was filtered and the debris remained on the membrane. The membrane was stained with hematoxylin-eosin (HE) solution and then mounted onto a glass slide for visualization.

RESULTS

Microscopic observation of the slide revealed several debris such as atheromatous plaques and intimal strips. HE staining facilitates the characterization of the debris composition. In addition to the histological evaluation, this technique revealed the particle size as well as the quantity of debris. The resulting HE slide is also suitable for permanent storage. In addition to the qualitative and quantitative qualities, this simple technique requires neither specific instrumentation nor equipment.

DISCUSSION

Carotid plaque debris aspirated during carotid artery stenting under distal protection can be filtered and visualized on a permanent glass slide. This simple method allows us to better understand quantity, particle size, and composition of debris.

Proximal Endovascular Flow Blockage for Cerebral Protection During Carotid Artery Stenting:Results From a Prospective Multicenter Registry

PURPOSE

To evaluate the feasibility of cerebral protection during carotid artery stenting (CAS) using the Mo.Ma device, which prevents cerebral embolization by proximal endovascular blockage of blood flow in the internal and external carotid arteries.

METHODS

In 14 European centers, 157 patients (121 men; mean age 68.0+/-8.3 years) were enrolled in a prospective registry between March 2002 and March 2003. Eligible patients had a symptomatic (>50%) or asymptomatic (>70%) stenosis of the internal carotid artery suitable for carotid stenting. Protected carotid stenting was performed with the Mo.Ma system, which occludes both the common and external carotid arteries via 2 independently inflatable compliant low-pressure balloons before any device is advanced across the lesion. Blood is aspirated through the catheter intermittently or at the end of the procedure.

RESULTS

The device was successfully positioned and stents were implanted in all cases. Diameter stenosis was reduced from 84.1%+/-7.8% to 6.7%+/-5.1%. The mean duration of flow blockage was 7.6+/-5.9 minutes. In 12 (7.6%) patients, transient intolerance to flow blockade was observed, but the procedures were completed successfully. In 124 (79.6%) cases, there was macroscopic evidence of debris after filtering the aspirated blood. In-hospital complications included 4 (2.5%) minor strokes, 8 (5.1%) transient ischemic attacks, no deaths, and no major strokes, resulting in a 2.5% death/stroke rate at discharge. At 30-day follow-up, there was 1 cardiac death, 1 major stroke, and 3 minor strokes, for an overall 5.7% 30-day death/stroke rate and a 30-day major stroke and death rate of 1.3%.

CONCLUSIONS

Cerebral protection with proximal endovascular blood flow blockage during CAS is feasible, with a high procedural success rate.

Angioplasty and stenting of the cervical carotid bifurcation under filter protection: a prospective study in a series of 53 patients

The aim of this study is to assess safety, reliability, ease of use and usefulness of filter protection devices during angioplasty and stenting of stenotic lesions of the cervical carotid bifurcation. Over a period of 42 months, 53 patients harboring a cervical carotid bifurcation stenotic lesion were treated, by angioplasty and/or stenting using filter protection devices of different kinds. The stenosis was atherosclerotic in 48 cases, post-surgical in four and post-radiation in one case. In all cases, the treatment was successful, with good restoration of the luminal diameter. There were three major strokes (5.6%) and one minor stroke (1.9%). Two of these (one major, one minor) occurred a few hours after the stenting procedure and both seemed by all evidence due to a hemorrhagic hyperperfusion syndrome. One hemiparesis and dysphasia occurred two days after the procedure, secondary to subacute thrombosis with occlusion of the stent. One patient complained of three episodes of decrease in visual acuity of the eye ipsilateral to the stenting in the two weeks following treatment. In conclusion, in our experience, use of the devices adds only few minutes to the procedure time; direct lesions of the arterial wall, such as dissections or intraluminal thrombi, related to the use of filters were never observed, and spasm of the distal I.C.A. also proved rapidly regressive. The content of all filters, if any, was histologically examined, but plaque material was found only in one case, probably owing to our primary stenting technique without use of pre-dilation. The major technical drawback is in-filter coagulation, which occurred in 16 cases, occluding the membrane of the filter and thus slowing or blocking intracranial flow. Such an event can be counteracted by a more aggressive anti-coagulation protocol, which could, however, be responsible for the two complications with hemorrhagic brain infarction. Furthermore, we observed two other major neurological events, which bring the incidence of neurological complications in this series as high as 7.5%. Therefore, it is our opinion that safety of filters is not yet proven, and consequently great care must be taken in their use.

[Distal protection devices in carotid stent]

Endovascular treatment of carotid stenoses is increasingly used. Frequently temporary occlusion balloons or filters are placed distal to the stenosis to gain additional protection against cerebral emboli. There is still a scientific debate about the usefulness of such distal protection devices. The following contribution reviews existing techniques and their clinical results and should allow for a critical discussion and selection of current techniques and materials.

Carotid artery surgery vs. stent: A cardiovascular perspective

Stroke is a major health catastrophe that is responsible for the third most common cause of death and the leading cause of disability. Carotid artery stenosis is an important cause of brain infarctions and the risk of stroke is directly related to the severity of carotid artery stenosis and to the presence of symptoms. Familiarity with different methods of measuring degrees of carotid artery stenosis is a key in understanding the role of revascularization of this disorder. Carotid endarterectomy (CEA), surgical removal of the carotid atherosclerotic plaque, is intended to prevent stroke in patients with carotid artery stenosis and currently the most commonly performed vascular procedure in the United States. Several randomized clinical trials had demonstrated the benefits of CEA in selected groups of patients with symptomatic and asymptomatic carotid artery stenosis. However, CEA can cause stroke, the very thing it intended to prevent, and is associated with significant perioperative complications such as those related to general anesthesia, cardiac or nerve injury. Moreover, several anatomical and medical conditions may limit candidates for CEA. Carotid artery stenting (CS) is an evolving and less invasive technique for carotid artery revascularization. Recent studies demonstrated that CS with embolic protection devices has become an alternative to CEA for high-surgical-risk patients and the procedure of choice for stenoses inaccessible by surgery. The role of CS in low risk patients awaits the completion of several ongoing studies.

Relationship of Matrix Metalloproteinases and Macrophages to Embolization During Endoluminal Carotid Interventions

PURPOSE

To investigate if relationships exist among macrophage infiltration, plasma matrix metalloproteinase (MMP) levels, and the number of emboli generated during endoluminal carotid interventions.

METHODS

Carotid endarterectomy specimens excised as intact cylinders (n=27) were subjected to a standardized angioplasty procedure under radiological guidance in an ex vivo pulsatile flow model. Emboli collected in distal filters were counted and sized using microscopy. Preoperative plasma gelatinase activity was determined by gelatin zymography and quantified using image analysis software. Levels of tissue inhibitors of metalloproteinases (TIMP) 1 and 2 were determined by ELISA. Macrophages within postangioplasty plaques were analyzed using immunohistochemical staining for CD68 antigen and graded by a blinded examiner. Statistical analysis was performed using Spearman's rank correlation.

RESULTS

The median number of emboli recorded during angioplasty was 104 (interquartile range 33.75-242.5, absolute range 13-1090). Plasma MMP-9 and MMP-2 levels correlated with emboli number (r=0.544 [p=0.003] and r=0.412, [p=0.033], respectively), while TIMP-1 and TIMP-2 levels did not. Macrophage infiltration within the plaques correlated with emboli number (r=0.722, p<0.001) and the plasma MMP-9 level (r=0.489, p=0.010).

CONCLUSIONS

These data indicate that plaque macrophage infiltration may play a role in the generation of emboli during endoluminal carotid intervention, possibly via modulation of protease activity.

A cardiologist in the carotids

Carotid endarterectomy for stroke prevention has been the standard of care for 50 years in patients with extra-cranial carotid bifurcation disease. Over the past decade, carotid stenting has emerged as a viable alternative to surgery. Combined with filter embolic protection devices, both a randomized control trial (Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy registry [SAPPHIRE]) as well as registry data (ACCULINK for Revascularization of Carotids in High Risk Patients registry [ARCHeR] and Registry Study to evaluate the Neuroshield Bare-Wire Cerebral Protection System and X-Act Stent in patients at high risk for Carotid Endarterectomy [SECuRITY]) have compared favorably to endarterectomy in patients at high risk for operative revascularization. Conditions associated with high operative risk included patients with significant cardiac, pulmonary, and renal disease; previous neck operation; previous radiation; and anatomically difficult surgical access. On the basis of these results, a carotid stent system approved by the Food and Drug Administration (FDA) is anticipated in 2004. Although this will be a welcome addition to endarterectomy in the armamentarium of therapeutic options for patients with carotid disease, several challenges lie ahead. Coverage and reimbursement for the carotid stenting has been severely restricted to include only those procedures performed as part of an FDA investigational device exemption trial protocol, and a national noncoverage decision will have to be reckoned with before broader coverage can be put into place (assuming FDA approval). In addition, the level of national expertise in carotid endovascular intervention is limited, and training will need to be tailored to the three specialties likely to perform the procedure: cardiology, radiology, and vascular surgery. Each of these specialties will have specific, and different, requirements for their training, further complicating the task of education.

Routine use of cerebral protection during carotid artery stenting: results of a multicenter registry of 753 patients

PURPOSE

To evaluate the short-term outcome of patients who underwent carotid stenting with the routine use of cerebral protection devices.

METHODS

In five centers, 808 successful stent procedures (of 815 attempted) were performed in 753 patients (557 [74%] men; mean [+/- SD] age, 70 +/- 8 years). Cerebral protection involved distal filter devices (n=640), occlusive distal balloons (n=144), or proximal balloon protection (n=24).

RESULTS

The protection device was positioned successfully in 793 (98.2%) of the 808 attempted vessels. Neurologic complications occurred within 30 days after 46 procedures (5.6%), including seven major strokes, 17 minor strokes, and 22 transient ischemic attacks. There were four deaths (one following a major stroke). The 30-day incidence of stroke and death was 3.3% (27/815). The rate of stroke or death was 3.8% (8/213) for symptomatic lesions and 3.2% (19/602) for asymptomatic lesions (P=0.87), and 3.4% (25/729) in patients aged <80 years and 2% (2/86) in those aged > or =80 years (P=0.81). Protection device-related vascular complications, none of which led to neurologic symptoms, occurred after nine procedures (1.1%).

CONCLUSION

In this uncontrolled study, routine cerebral protection during carotid artery stenting was technically feasible and clinically safe. The incidence of major neurologic complications in this study was lower than in previous reports of carotid artery stenting without cerebral protection.

Evolution of Neuroendovascular Intervention: A Review of Advancement in Device Technology

NEUROENDOVASCULAR SURGERY IS a rapidly evolving field. Each year, numerous improvements are made in the endovascular surgeon's armamentarium. This evolution in technology, which is occurring at a dizzying pace, addresses many of the current limitations of neuroendovascular approaches. The potential to improve the outcomes of our patients is tremendous, particularly because one of the most common and most devastating neurological disorders, ischemic stroke, remains largely untreated. This article presents several of the new technologies that are currently being investigated or are under development and have the potential to lead to major advances in endovascular approaches for the treatment of intracranial and extracranial diseases.

Carotid Angioplasty and Stenting versus Carotid Endarterectomy for Treatment of Asymptomatic Carotid Stenosis: A Randomized Trial in a Community Hospital

OBJECTIVE

Carotid endarterectomy (CEA) is effective in reducing the risk of stroke in individuals with more than 60% carotid stenosis. Carotid angioplasty and stenting (CAS) has been proffered as effective and used in treating individuals with asymptomatic carotid stenosis despite the absence of proven clinical equivalency. This randomized trial was designed to explore the hypothesis that CAS is equivalent to CEA for treating asymptomatic carotid stenosis.

METHODS

A total of 85 individuals presenting with asymptomatic carotid stenosis of more than 80% were selected randomly for CAS or CEA and followed up for 48 months.

RESULTS

Stenosis decreased to an average of 5% after CAS. The patency of the reconstructed artery remained satisfactory regardless of the technique, as determined by carotid ultrasonography. No major complications such as cerebral ischemia or death occurred. Procedural complications associated with CAS (n = 5) were hypotension and/or bradycardia; those concomitant with CEA (n = 3) were cervical nerve injury or complications related to general anesthesia (n = 4). Both procedures were well tolerated in the context of pain and discomfort. Hospital stay was similar in the two groups (mean, 1.1 versus 1.2 d). The occurrence of complications associated with CAS or CEA prolonged hospitalization by 3 days (mean, 4.0 versus 4.5 d). Return to full activity was achieved within 1 week by more than 85% of patients; all returned to their usual lifestyle by 2 weeks. Although hospital charges were slightly higher for CAS, costs were similar.

CONCLUSION

CAS and CEA may be equally effective and safe in treating individuals with asymptomatic carotid stenosis.

Complication with an embolic protection device during carotid angioplasty

A case of carotid artery stenting with an AngioGuard cerebral protection device is described in a patient with tight internal carotid stenosis. Deployment of AngioGuard induced sudden severe vasospasm, with subsequent minor stroke. According to our observations, AngioGuard may cause a vasospastic response with adverse neurologic effects.

A ?mouse in a trap? method for cerebral protection during carotid stenting: Technical note

Carotid artery angioplasty and stenting (CAS) is now used as an alternative to surgical endarterectomy. The introduction of cerebral protection systems during stenting has improved carotid artery stenosis treatment, with less periprocedural complications. A "mouse in a trap" method was conceived and used in three patients. This involved an emboli entrapment-aspiration system using one proximal occluder in the common carotid artery and two distal occluders in the internal carotid artery or external carotid artery, followed by serial inflation-deflation cycles during each carotid stenting procedure. Debris was retrieved before dilation in one patient, after deployment in one, and after dilation in two. Although only used in a few cases to date, the method may improve the practice of CAS in treating patients with carotid stenosis, resulting in less thromboembolic events.

Complications following Carotid Angioplasty and Carotid Stenting in Patients with Symptomatic Carotid Artery Disease

BACKGROUND

We review a single centre's experience of the endovascular treatment of carotid artery disease, present the 30-day and 1-year complication rates and assess whether changes in technique are associated with a change in clinical outcome.

METHODS

Patients who underwent carotid angioplasty with or without stenting for symptomatic > or = 70% carotid artery stenosis secondary to atherosclerosis were included. 333 procedures were performed, i.e. angioplasty alone (86), stent without cerebral protection (150) and stent with cerebral protection (97).

RESULTS

At 30 days, the total major disabling stroke and all death rate was 3.0%. For angioplasty alone, this was 2.3%, for stent without cerebral protection 4.0% and for stent with cerebral protection 2.1%. If non-stroke-related deaths were excluded, it was 2.3, 3.3 and 0%, respectively. After 30 days, the 1-year ipsilateral stroke rate was 0.8%.

CONCLUSIONS

Carotid artery stenting, in particular with a cerebral protection device, is a safe alternative to carotid endarterectomy for the treatment of symptomatic high-grade carotid artery disease.