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

Neutrophil Extracellular Traps and Thrombolysis Resistance: New Insights for Targeting Therapies

BACKGROUND

Thrombosis is linked to neutrophil release of neutrophil extracellular traps (NETs). NETs are proposed as a mechanism of resistance to thrombolysis. This study intends to analyze the composition of thrombi retrieved after mechanical thrombectomy, estimate the age and organization of thrombi, and evaluate associations with the use of thrombolysis, antiplatelets, and heparin.

METHODS

This retrospective observational study involved 72 samples (44 from cerebral and 28 coronary arteries), which were stained with hematoxylin and eosin, anti-NE (neutrophil elastase) antibody, and anti-histone H2B (histone H2B) antibody, representing different components in NET formation, all detectable during the later stages of NETosis, for histochemical and digital quantification of NET content. The histological and morphological evaluations of the specimens were correlated, through univariate and mediation analyses, with clinical information and therapy administered before intervention.

RESULTS

The results demonstrated that the composition of cerebral and coronary thrombi differs, and there were significantly more lytic cerebral thrombi than coronary thrombi (66% versus 14%; P=0.005). There was a considerably higher expression of NETs in the cerebral thrombi as testified by the higher expression of H2B (P=0.031). Thrombolysis was remarkably associated with higher NE positivity (average marginal effect, 6.461 [95% CI, 0.7901-12.13]; P=0.02555), regardless of the origin of thrombi. There was no notable association between the administration of antiaggregant therapy/heparin and H2B/NE amount when adjusted for the thrombus location. Importantly, the age of the thrombus was the only independent predictor of NET content without any mediation of the thrombolytic treatment (P=0.014).

CONCLUSIONS

The age of the thrombus is the driving force for NET content, which correlates with impaired clinical outcomes. The therapy that is currently administered does not modify NET content. This study supports the need to investigate new pharmacological approaches added to thrombolysis to prevent NET formation or enhance their disruption, such as recombinant human DNase I (deoxyribonuclease I).

Successful Retrieval of Filter Embolic Protection Device Fragment Trapped by a Carotid Stent: A Case Report

Objective

Embolic protection devices are useful for preventing distal embolism during carotid artery stenting (CAS); however, complications have been reported. The successful removal of a filter fragment trapped at the distal edge of a carotid stent during the retrieval procedure is described.

Case Presentation

CAS was performed for internal carotid artery stenosis in a patient in his 70s, and the carotid stent was successfully placed. During the retrieval procedure, the tip of the filter was trapped at the distal edge of the stent and detached from the filter. Using a snare kit, the filter tip was successfully retrieved, and no postoperative neurological symptoms occurred.

Conclusion

The edge of a carotid stent can potentially trap devices. When trapping or fragmentation of a device is suspected, it is necessary to evaluate the situation and cause, and the device should be appropriately retrieved without using force.

Effect of plaque morphological characteristics on the outcomes of carotid artery stenting

Carotid artery stenting (CAS) represents today an accepted option for the treatment of severe carotid artery stenosis. The evolution of materials, techniques, perioperative medical management and patients' selection, has allowed to progressively reduce CAS complications. However, the main drawback of CAS is still represented by the risk of cerebral embolization, that may occur during several steps of the procedure and also in the early postoperative period. Preoperative carotid plaque morphological characteristics may have a great role in determining the risk of embolization during CAS. This review summarizes the current knowledge on carotid plaque characteristics that may influence the risk of complication during CAS. This information may be important for the optimization of CAS patients' selection and adaptation of the materials and techniques.

Impact of Carotid Stent Design on Embolic Filter Debris Load During Carotid Artery Stenting

BACKGROUND

The carotid stent design may influence the risk of embolization during carotid artery stenting. The aim of the study was to assess this risk by comparing the quantity of embolized material captured by filters during carotid artery stenting, using different stent designs.

METHODS

We conducted a single-center retrospective study of patients undergoing carotid artery stenting for asymptomatic carotid stenosis >70% (2010-2022) in a tertiary academic hospital (Padua University Hospital, Italy). Carotid stents were classified according to their design as open-cell (OCS), closed-cell (CCS), or micromesh stents (MMS). A distal filter protection was used in all patients, and the amount of captured embolized particles was semiautomatically analyzed using a dedicated software (Image-Pro Plus, Media Cybernetics). Primary end point was embolic filter debris (EFD) load, defined as the ratio of the filter area covered by particulate material to the total filter area. Secondary end points were 30 days major stroke and death.

RESULTS

Four-hundred-eighty-one carotid artery stentings were included; 171 (35%) using an OCS, 68 (14%) a CCS, and 242 (50%) a MMS. Thirty-days mortality was 0.2% (n=1) and major stroke rate was 0.2% (P=0.987). Filters of patients receiving MMS were more likely to be free from embolized material (OCS, 30%; CCS, 13%; MMS, 41%; P<0.001) and had a lower EFD load (OCS, 9.1±14.5%; CCS, 7.9±14.0%; MMS, 5.0±9.1%; P<0.001) compared with other stent designs. After stratification by plaque characteristics, MMS had a lower EFD load in cases of hypoechogenic plaque (OCS, 13.4±9.9%; CCS, 10.9±8.7%; MMS, 6.5±13.1%; P<0.001), plaque length>15 mm (OC, 10.2±15.3; CC, 8.6±12.4; MM, 8.2±13.6; P<0.001), and preoperative ipsilateral asymptomatic ischemic cerebral lesion (OCS, 12.9±16.8%; CCS, 8.7±19.5%; MMS, 5.4±9.7%; P<0.001). After multivariate linear regression, use of MMS was associated with lower EFD load (P=0.038).

CONCLUSIONS

The use of MMS seems to be associated with a lower embolization rate and EFD load, especially in hypoechogenic and long plaques and in patients with a preoperative evidence of asymptomatic ischemic cerebral lesion.

The relationship between ultrasonographic plaque morphology and histopathology of embolic material captured in the protective filter during carotid artery stenting

PURPOSE

We aimed to correlate the presence or absence of embolic debris in filter-type embolic protection devices (EPD), which are frequently used during carotid artery stenting (CAS), with possible risk factors and ultrasonographic plaque features.

MATERIALS AND METHODS

Eighty patients, who underwent CAS using a filter-type EPD in the period between July 2016 and March 2019, were included in our study. The modified Gray-Weale classification (mGWC) subtypes obtained in the pre-procedural ultrasonographic examinations were recorded. In addition, other patient-related risk factors considered to be related to a distal embolism were recorded. After the procedure the filters were evaluated to detect and examine embolic debris in the pathology clinic. The presence and features of embolic debris in the filters were recorded.

RESULTS

In the examinations performed after CAS, embolic debris was macroscopically and microscopically detected in 22 (27%) and 34 (42.5%) of the filter-type EPDs, respectively. A significant correlation was found between the change in the mGWC category of stenotic plaques from type 5 to type 1 and the presence of embolic debris in the filter (p < 0.05). Furthermore, a significant relationship was found between stenotic segment length and the presence of embolic debris in the filter (p < 0.05). The presence of embolic debris was not statistically significantly related to predisposing risk factors for atherosclerosis (p > 0.05).

CONCLUSIONS

During CAS, the likelihood of the presence of embolic debris in the EPDs increases as mGWC categories change from type 5 to type 1 and as the length of the stenotic segment increases.

Procedural embolic protection strategies for carotid artery stenting: current status and future prospects

INTRODUCTION

Carotid artery angioplasty and stenting (CAS) is an established procedure to treat carotid artery stenosis for either primary or secondary prevention of stroke. Randomized clinical trials have shown an increased risk of periprocedural cerebrovascular events with CAS compared with carotid endarterectomy (CEA). Several strategies have been proposed to mitigate this risk, including alternative vascular access site, proximal/distal embolic protection devices, and dual-layer stents, among others.

AREAS COVERED

This review provides a general overview of current embolic protection strategies for CAS. The phases of the procedure which can affect the early risk of stroke and how to reduce it with novel techniques and devices have been discussed.

EXPERT OPINION

Innovations in device technologies have dramatically improved the safety and efficacy of CAS. To minimize the gap with surgery, a thorough, patient-oriented approach should be pursued. Endovascular technologies and techniques should be selected on an individual basis to address unique lesion characteristics and vascular anatomies. Meticulous pre-procedural planning, both clinical and anatomical, is needed to assess the embolic risk of each procedure. Only by having an in-depth understanding of the wide range of available endovascular devices and techniques, the operator will choose the most appropriate strategy to optimize CAS results.

From surgical clamping to endovascular flow arrest/reversal: the concept behind the system

Carotid artery lesions are frequently composed of friable, thrombotic, ulcerated and/or hemorrhagic materials which can embolize during surgical or endovascular interventions. The use of embolic protection devices (EPD) during carotid angioplasty and stenting (CAS) has been proven to be associated with a reduction of the embolic load. Many studies indicate that the clinical results of CAS are comparable with the best surgical series, when EPD are routinely applied. The proximal EPD work by interrupting or reversing the blood flow in the common carotid artery/internal carotid artery (CCA/ICA). Once established the endovascular flow arrest/reversal, these systems have the advantages of promoting a protected crossing of the lesion and blocking both macro-emboli and micro-emboli. Moreover, proximal neuroprotection implies no manipulation of the device in the distal ICA, neither during device deployment nor during device retrieval, and reduces the risk of arterial spasm, dissection, or intimal damage. The choice between transfemoral and transcervical proximal EPD should account for different factors: local availability, operator expertise, and patient characteristics including anatomical features precluding flow arrest/reversal (e.g., incomplete circle of Willis), femoral access (e.g., unfavorable aortic arch anatomy), or transcervical access (e.g., diseased CCA).

Clinical Utility of Intravascular Ultrasound (IVUS) in Carotid Artery Interventions: A Systematic Review and Meta-analysis

BACKGROUND

Carotid plaque morphology plays an important role in determining outcome of carotid artery stenting (CAS). Intravascular ultrasound (IVUS) and its extension VH (Virtual Histology)-IVUS evaluate plaque characteristics in real time and guide decision making during stenting. To date, there is no consensus about indications of IVUS and its validated methods. This systematic review and meta-analysis aims to evaluate the clinical utility of IVUS in carotid artery interventions (CAS) and develop a future consensus for research and practice parameters.

METHODS

A systematic review and meta-analysis was performed of the English literature articles published till February 2021. Studies reporting on IVUS parameters and findings and also its performance compared with other imaging modalities were included in review. Pooled prevalence with 95% confidence intervals (CI) was calculated. The statistical analysis was conducted in R version 3.6.2.

RESULTS

A total of 2015 patients from 29 studies were included. Proportional meta-analysis was performed on 1566 patients from 11 studies. In 9 studies, stroke/transient ischemic attack (TIA) had a pooled prevalence of 4% (95% CI 3%-5%) while asymptomatic stroke had a pooled prevalence of 46% (95% CI 31%-62%) in 4 studies following IVUS. Two studies reported that IVUS detected more plaque protrusion compared with angiography (n=33/396 vs 11/396). IVUS led to stent type or size change in 8 of 48 cases which were missed on angiography in 3 other studies. Concordance between VH-IVUS and true histology was good at 80% to 85% reported in 2 studies.

CONCLUSIONS

This systematic review and meta-analysis showed, though IVUS fared better to computed tomography (CT)/magnetic resonance (MR) angiography for better stent selection during CAS, with low to moderate risk of bias in the studies included. However, large scale, preferably randomized controlled studies are needed to predict its role in determining clinical outcome.

Is it possible to prevent cerebral embolization by improving the design and technology of carotid stent implantation?

INTRODUCTION

The prevention of atherosclerotic plaque fragmentation during carotid artery stenting is a fundamental problem in decreasing the risk of disability of patients. The goal of this review is to clarify whether the stent design can have a decisive impact on the rate of intraoperative and postoperative complications.

AREAS COVERED

Different designs of the carotid stents are briefed and the advantages and disadvantages of different stent designs are discussed as well as the results of their clinical use. Various solutions are presented to reduce cerebral embolism during carotid artery stenting.

EXPERT OPINION

There is no conclusive evidence for the benefits of closed cell and hybrid stents. The stent design cannot completely resolve the problem of cerebral embolism. Most of the events of cerebral microembolism occur at the stages of stent delivery rather than protrusion of an atherosclerotic plaque in the long-term follow-up. Most likely, minimization of the risks for periprocedural and postprocedural strokes requires not only the new solutions in stent design as well as the corresponding delivery systems and brain embolic protection systems, but also the new strategies of preprocedural drug stabilization of the atherosclerotic plaque in the carotid artery. Abbreviations: CAS, carotid artery stenting; CE, carotid endarterectomy; DW-MRI, diffusion-weighted magnetic resonance imaging; ECA, external carotid artery; ICA, internal carotid artery; IVUS, intravascular ultrasound examination; OCT, optical coherence tomography.

The utility of adjunctive electroencephalography while performing transcarotid artery revascularization

Transcarotid artery revascularization (TCAR) has been used as an alternative to carotid endarterectomy and transfemoral carotid artery stenting. Although TCAR has been associated with a decrease in perioperative strokes compared with transfemoral carotid artery stenting, little is known about the safety of cerebral blood during flow reversal or the value of adjunctive electroencephalography (EEG) monitoring in performing TCAR. We describe two cases of EEG changes in patients undergoing TCAR. These cases highlight the use of adjunctive EEG and provide examples of test clamping to assess for compromised collateral cerebral blood flow in patients undergoing TCAR.

Transcarotid Artery Revascularization With Flow Reversal

Purpose: To report a study evaluating the safety and efficacy of stenting via direct carotid access with flow reversal using the ENROUTE Transcarotid Neuroprotection System. Methods: Between March 2009 and June 2012, 75 patients (mean age 72.6 years; 45 men) underwent carotid artery stenting with the ENROUTE System; the majority of patients (63, 84%) were asymptomatic. The primary safety endpoint was the composite of major stroke, myocardial infarction, or death at 30 days. Efficacy outcomes included acute device success, procedure success, and tolerance to flow reversal. Fifty-six (74.7%) patients underwent diffusion-weighted magnetic resonance imaging (DW-MRI) before and after the procedure to assess the development of new ischemic brain lesions. Results: Acute device and procedure success were achieved in 68 (90.6%) patients. The reverse flow circuit was established in 71 (94.6%) patients; only 5 patients demonstrated transient intolerance to flow reversal that did not interfere with completion of the procedure. The mean time on flow reversal was 19.1 minutes. In the DW-MRI substudy, 10 (17.9%) of 56 patients had ipsilateral new white lesions with a mean volume of 0.17 mL. At 30 days, no major stroke, myocardial infarction, or death occurred; 1 patient had experienced a minor stroke that was adjudicated as not related to either the device or procedure. Conclusion: Results of the PROOF study demonstrate the safety and efficacy of transcarotid revascularization with the ENROUTE Transcarotid Neuroprotection System.

A Microscopic and Biomarker Evaluation of Embolic Filter Debris Collected During Carotid Artery Stenting

PURPOSE

To evaluate and characterize debris retrieved from the cerebral embolic protection devices (EPDs) used during carotid artery stenting (CAS) and compare debris size, volume, tissue types, cellular composition, and protein biomarker expression in symptomatic and asymptomatic patients.

METHODS

Distal protection filters were retrieved from 22 consecutive patients (mean age 71.6 years, range 52-85; 16 men) undergoing elective CAS between July 2012 and February 2014 for >70% internal carotid artery stenosis (mean 85.4% ± 10.3%). Six patients were symptomatic. The debris within each EPD was visually characterized using stereomicroscopy and then processed for histology and immunohistochemistry. Biomarkers were immunohistochemically measured to evaluate plaque stability [matrix metalloproteinase-9 (MMP-9)], inflammation [glycoprotein CD68 and interleukin-6 (IL-6)], or phenotype [smooth muscle (SM)-actin and type IV collagen]. The immunohistochemical results were measured using semiquantitative grading criteria based on both staining intensity and distribution in the samples.

RESULTS

Macroscopic debris was visible in 5/22 EPDs; 3 of the 5 filters came from symptomatic patients. Microscopic debris was detected in all filters and ranged in size from 0.01 to 8.57 mm(2). Debris consisted of calcified, fibrous, and necrotic tissue, as well as fibrin and foam cells with no significant difference between the symptomatic and asymptomatic groups. There was no association between the degree or type of embolic material and stenosis severity, carotid tortuosity, calcium grade, soft plaque, or arch type. Symptomatic patients had a larger volume of debris (8.24 vs 0.58 mm(3), p<0.01), mean particle size (1.30 vs 0.32 mm(2), p<0.001), and expression of biomarkers IL-6 (2.17 vs 0.81, p<0.05), CD68 (2.00 vs 0.38, p<0.01), SM-actin (1.00 vs 0.25, p=0.055), type IV collagen (1.17 vs 0.25,p=0.082), and MMP-9 (1.00 vs 0.06, p<0.05).

CONCLUSION

Histological analysis revealed particulate embolization in all EPDs used during CAS. Symptomatic patients had a larger volume of embolic debris, mean particle size, and the biomarkers associated with inflammation, necrotic core, and diminished fibrous cap.

Follow-up after undersized dilatation of targeted lesions in carotid artery stenting

BACKGROUND AND PURPOSE

We assessed whether intentional undersized dilatation of targeted lesions during carotid artery stenting (CAS) carried a higher risk of in-stent restenosis (ISR) and correlation to subsequent ischemic stroke in qualifying arteries in the follow-up period.

METHODS

Consecutive patients undergoing CAS between April 2003 and May 2010 were retrospectively reviewed. The use of a filter device as a distal embolic protection device (EPD) was first approved by Japanese governmental health insurance in April 2008; previously, transient balloon occlusion was used off-label. Until March 2008 (Group A), the target diameter of balloon dilatation was 80-100% of the normal vessel diameter just distal to the stenotic lesion. Moderately undersized dilatation (70-80% of the normal vessel diameter) using the distal EPD was adopted in April 2008 (Group B) in an attempt to reduce the amount of released plaque debris.

RESULTS

We analyzed 132 CAS procedures (125 patients) in Group A and 53 CAS procedures (52 patients) in Group B. The mean follow-up period was 35.4 months (35.3 months in Group A and 36.0 months in Group B). Eight lesions (4.3%; 7 in Group A and 1 in Group B) developed ISR. None of the patients had symptomatic ISR, and ISR did not increase in Group B (odds ratio, 0.34; 95% confidence interval, 0.04-2.86; p = 0.32).

CONCLUSIONS

Undersized dilatation of targeted lesions did not increase the risk of developing ISR, and we suggest it as a viable treatment option to prevent ischemic events during CAS.

Pathology of embolic debris in carotid artery stenting

BACKGROUND

The relationship between magnetic resonance (MR) plaque imaging and the pathology of distal embolic debris is unknown. We aimed to evaluate the relationship between the pathology of embolic debris in the embolic filter during carotid artery stenting (CAS), MR plaque imaging, and new ischemic lesions on diffusion-weighted imaging (DWI).

METHOD

We prospectively reviewed the 36 patients who underwent CAS using a filter-type embolic protection device. Pathology of debris was categorized into thrombosis, inflammatory cells, elastic fiber, and calcification. We compared the clinical parameters, MR plaque imaging, and pathological characteristics of the embolic debris retained in the filter during CAS on univariate analysis.

RESULTS

Eleven patients had and 25 patients did not have new lesion on DWI. All of DWI-high lesions were identified in affected side middle cerebral artery territory. Embolic debris was microscopically confirmed in 28 patients (78%); thrombosis in 11 (31%), inflammatory cells in 13 (36%), elastic fiber in 12 (33%), and calcification in 9 (25%). Proportion of asymptomatic carotid stenosis, intra-operative bradycardia/hypotension, and inflammatory cells of debris were significantly higher in patients with new DWI-high lesions. There was no significant relationship between the pathological characteristics and MR plaque imaging of distal embolic debris.

CONCLUSIONS

Our study showed that new DWI-high lesions might be influenced by types of debris in the filter. The need for future studies specifically examine the association of pathology of debris and findings of MR plaque imaging with new DWI-high lesions during CAS is emphasized.

Carotid artery stenting: current and emerging options

Carotid artery stenting technologies are rapidly evolving. Options for endovascular surgeons and interventionists who treat occlusive carotid disease continue to expand. We here present an update and overview of carotid stenting devices. Evidence supporting carotid stenting includes randomized controlled trials that compare endovascular stenting to open surgical endarterectomy. Carotid technologies addressed include the carotid stents themselves as well as adjunct neuroprotective devices. Aspects of stent technology include bare-metal versus covered stents, stent tapering, and free-cell area. Drug-eluting and cutting balloon indications are described. Embolization protection options and new direct carotid access strategies are reviewed. Adjunct technologies, such as intravascular ultrasound imaging and risk stratification algorithms, are discussed. Bare-metal and covered stents provide unique advantages and disadvantages. Stent tapering may allow for a more fitted contour to the caliber decrement between the common carotid and internal carotid arteries but also introduces new technical challenges. Studies regarding free-cell area are conflicting with respect to benefits and associated risk; clinical relevance of associated adverse effects associated with either type is unclear. Embolization protection strategies include distal filter protection and flow reversal. Though flow reversal was initially met with some skepticism, it has gained wider acceptance and may provide the advantage of not crossing the carotid lesion before protection is established. New direct carotid access techniques address difficult anatomy and incorporate sophisticated flow-reversal embolization protection techniques. Carotid stenting is a new and exciting field with rapidly advancing technologies. Embolization protection, low-risk deployment, and lesion assessment and stratification are active areas of research. Ample room remains for further innovations and developments.

Pathophysiology of flow impairment during carotid artery stenting with an embolus protection filter

OBJECTIVE

Carotid artery stenting (CAS) is a well-accepted treatment for atherosclerotic stenosis of carotid arteries. Since the occurrence of distal embolization with CAS is still a major concern embolus protection devices (EPD) are usually employed during the procedure. We examined two types of embolus protection filters (Angioguard XP (AG); Filterwire EZ (FW)) and evaluated the function. Thus, the filter was examined postoperatively and the cause of intraoperative flow impairment was evaluated.

MATERIALS AND METHODS

CAS was performed for 54 patients with carotid artery stenosis (55 lesions: 25 AG; 27 FW; 3 others). After completing CAS the filter membrane was stained with hematoxylin-eosin (HE) solution and removed from the filter strut. Once mounted on a glass slide the filter was evaluated under a microscope. The area occupied with debris was measured and the relationship to intraoperative flow impairment was evaluated. Furthermore, the relationship between perioperative ischemic complications and intraoperative flow impairment was statistically analyzed.

RESULTS

Microscopic observation of the slide revealed the pore density of the FW was 1.5 times higher than that of the AG and the filter area of the FW was 2.5 times wider than than the AG. HE staining facilitated characterization of the debris composition. The area occupied with debris was significantly more in the AG (0.241 ± 0.13 cm(2)) than in the FW (0.129 ± 0.093 cm(2)). Thus, fibrin was significantly more precipitated in the AG. Flow impairment occurred in 6 AG cases (24.0 %) and 4 FW cases (14.8 %). It was induced by filter obstruction in the AG and by vasospasms in the FW. Three cases treated with AG (12.0 %) were complicated with cerebral infarction and all of them were related to flow impairment. One FW case (3.7 %) was complicated with cerebral infarction in presence of preserved flow throughout the intervention.

CONCLUSION

Filter function is different according to each design. The cause of flow impairment was attributable to filter obstruction in the AG group and to vasospasms in the FW group. Filter obstruction tends to result in cerebral infarction.

Inflammatory mediators and cerebral embolism in carotid stenting: new markers of risk

PURPOSE

To investigate serological predictors of risk for cerebral embolism after carotid artery stenting (CAS).

METHODS

Twenty consecutive symptomatic and asymptomatic patients (13 men; mean age 74 years) with carotid artery stenosis undergoing standardized filter-protected CAS (Wallstent) were preoperatively evaluated to identify unstable plaque (duplex ultrasound), complicated aortic plaque (transesophageal echocardiography), and inflammatory status [high-sensitivity C-reactive protein (hs-CRP) and serum amyloid-A protein (SAA) serum levels]. Aortic arch type, carotid tortuosity, and complexity of the procedure were considered. Cerebral embolism was evaluated by comparing the number, volume, and side (ipsilateral and non-ipsilateral) of preoperative and postoperative cerebral lesions detected on diffusion-weighted resonance magnetic imaging (DW-MRI) and through light and scanning electron microscopy analysis of cerebral protection filters obtained from CAS.

RESULTS

All CAS procedures were completed with no complications. All patients had a negative preoperative DW-MRI, but at least 1 asymptomatic cerebral lesion appeared on DW-MRI after the procedure in 18 (90%) patients. Female gender was associated with a higher number of cerebral lesions (18.2±10.9 vs. 8.3±8.8 for men, p=0.03). Carotid plaque morphology, supra-aortic vessel anatomy, and procedure complexity did not correlate with number or volume of new cerebral lesions. Complicated aortic plaque was associated with a higher volume of non-ipsilateral cerebral lesions than uncomplicated plaque (235.0±259.3 vs. 63.6±63.2 mm(3), respectively; p=0.02). Hs-CRP ≥5 mg/L and SAA ≥10 mg/L were significantly associated with a higher number of new cerebral lesions [16.2±10.7 vs. 4.3±3.4 for hs-CRP <5 mg/L (p=0.02) and 14.8±10.3 vs. 2.8±3.4 for SAA <10 mg/L (p=0.006), respectively]. Hs-CRP ≥5 mg/L and SAA ≥10 mg/L also correlated with greater surface involvement by embolic materials in the protection filters at microscopic analysis [37.0% (5.1%) vs. 26.9% (2.5%) for hs-CRP <5 mg/L, p=0.004; 35.9% (13.5%) vs. 22.2% (6.9%) for SAA <10 mg/L, p=0.02].

CONCLUSION

In addition to female gender and the presence of complicated aortic plaque, inflammatory status can be a predictor of cerebral embolism in CAS.

Incidence of arterial micro-embolization during percutaneous AngioJet thrombectomy of hemodialysis grafts

PURPOSE

This study was designed to investigate the incidence of arterial embolization using a peripheral protection filter device in a series of patients undergoing percutaneous mechanical thrombectomy for the management of thrombosed hemodialysis arteriovenous grafts (AVGs).

METHODS

This prospective, single-center study included all eligible patients presenting during an 18-month period to undergo AVG percutaneous thrombectomy. Inclusion criteria was a recently thrombosed AVG with 2 cm of artery before the next arterial branching. Primary endpoint was the incidence of distal arterial macro- and micro-embolization determined by both digital subtraction angiography and histopathological analysis of the material collected. Secondary endpoints included quantitative measurements of the specimens using a 0+ (no material) to 3+ (maximum load) score.

RESULTS

In total, 42 patients met the study's inclusion criteria. No procedure-related complications or angiographically evident arterial embolization were noted. Macroscopically evident material was present in 47.6% (20/42 filters). Histopathology demonstrated that the embolic material was primary consisted of fibrin conglomerates and platelets (median score: 1.5, confidence interval: 1.0-3.0), whereas inflammatory cells, trapped erythrocytes, extracellular matrix, cholesterol clefts, foam cells, necrotic core, and smooth muscle cells also were detected. Mean total area of embolic material was 5.04 mm(2) (range 0.05-5.21). The mean major axis of the largest particle was 1.83 mm (range 0.29-6.64), whereas 19% (8/42) contained particles with major axis >1 mm and 12% (5/42) with major axis >3 mm.

CONCLUSIONS

In this study, the percentage of arterial micro-embolization was significantly higher than previously reported. However, the detrimental, long-term, clinical relevance remains to be determined.

Propagation-based phase-contrast X-ray microtomography of a cerebral protection device retrieved after carotid artery stenting

Phase-contrast synchrotron X-ray microtomography (pcSyncX) based on the highly coherent X-ray beam has previously been used to visualize the microstructures of biologic specimens, but it has never been used to evaluate embolic debris adherent on a cerebral protection device (CPD). The purpose of this study was to demonstrate the feasibility of pcSyncX for evaluating embolic debris during carotid artery stenting (CAS). Five patients (four males, age range 67-77 years) with severe carotid artery stenosis underwent CAS. The retrieved CPD was exposed to synchrotron radiation and 1000 pcSyncX projection images were obtained by rotating the CPD through 180°. An X-ray shadow of a CPD was converted into a visual image by the scintillator. After microtomographic reconstruction, the three-dimensionally reconstructed images were further segmented into the embolic debris and CPD. The total volume of emboli was calculated by summing the volume at each scanning level. The number of membrane pores covered by emboli as seen from the outer surface was counted and the percentage of covered area was calculated. Embolic debris was clearly demonstrated not only on the inner surface and within pores but also on the outer surface of the CPD. The mean total volume of embolic debris was 0.538 × 10(-6) mm(3) (range 0.225-0.965 × 10(-6) mm(3)). Most (61.5%) of the debris was located at the apical one-third of the CPD and 20.8% of the pore area was covered by debris.

Cognitive performance after carotid angioplasty and stenting with brain protection devices

OBJECTIVE

Neuropsychological outcomes after carotid endarterectomy (CEA) have been investigated extensively. However, cognitive impacts of carotid angioplasty and stenting (CAS), an emerging alternative to CEA, have not been studied. This study is aimed at investigating pattern and degree of cognitive changes after CAS among patients with high-grade carotid stenosis.

PATIENTS AND METHODS

Fifty-four patients with high-grade carotid artery stenosis and received elective CAS were followed. Sixty-six patients with similar medical conditions requiring carotid angiography (CAG) were enrolled as controls. Cognitive functions among patients in both groups were evaluated at baseline and follow-ups utilizing a battery of neuropsychometric tests. Results were analysed by inter-group and within-group comparisons.

RESULTS

There were no statistically significant differences between CAS and CAG patients regarding demographic characteristics, risk factors for stroke and baseline cognitive performance (p>0.05). CAS patients performed significantly better than CAG patients in Rey auditory verbal learning tests (RAVLT) at week 1 (41.2 +/- 5.2 versus 37.4 +/- 4.0, p<0.001) and week 12 follow-ups (43.3 +/- 7.7 versus 37.3 +/- 4.5, p<0.001). Comparison of z score also indicated CAS patients improved significantly more than CAG patients in RAVLT at both weeks 1 (1.08 +/- 1.29 versus 0.25 +/- 0.99, p<0.001) and 12 follow-ups (1.62 +/- 1.95 versus 0.05 +/- 1.02, p<0.001).

CONCLUSION

CAS patients demonstrated improvement in verbal memory after procedures. Correction of cerebral hypoperfusion and reduction of artery-to-artery embolization after CAS are postulated responsible for the cognitive improvement.

Recanalization of acute carotid stent occlusion using Penumbra 4Max aspiration catheter: technical report and review of rescue strategies for acute carotid stent occlusion

Carotid artery stenting (CAS) has become a widely used treatment for carotid artery stenosis, especially in high-risk patients. Acute in-stent and distal protection device occlusion are potentially catastrophic complications of this procedure. Previously described rescue strategies have included administration of antiplatelet agents (eg, abciximab) with/without thrombolytics and removal of the filter. Here we describe the successful resolution of in-stent occlusion by mechanical thrombolysis using the Penumbra 4Max aspiration catheter. Distal flow was subsequently restored with minimal residual stenosis. The patient did not suffer any consequent neurological deficits. The different strategies that could be used in this critical situation are reviewed.

Captured Macro-embolus of Fractured Atheromatous Plaque by the Embolic Protection Device during Carotid Stent Assisted Angioplasty

The authors present a case in which macro-embolus from the ruptured atheromatous plaque developed during carotid artery stenting (CAS). A 63-year-old man who had suffered a left middle cerebral artery territory infarction had significant proximal left internal carotid artery stenosis required CAS procedure. Immediate after stent deployment, the patient showed abrupt neurological deterioration with 12 × 3 mm sized macro-embolus which was caught by the embolus protection device (EPD). Retrieval of the macro-embolus was performed safely and the patient recovered to pre-procedure status. Macro-embolus can be resulted during the CAS. The EPD can capture the macro-embolus and safe removal is technically feasible.

Identification of high-risk carotid artery stenosis: motion of intraplaque contents detected using B-mode ultrasonography

Object

Identification of the risk of rupture and vulnerability of arterial plaque is not yet clearly understood. The aim of this study was to assess the clinical features of the motion of intraplaque contents (MIC) detected by B-mode ultrasonography. The MIC is characterized by the peculiar movement of the intraplaque contents that is not synchronized with the heartbeat; however, the movement of the carotid artery (CA) wall depends on the heartbeat.

Methods

From January 2008 to November 2010, 1798 consecutive patients with transient ischemic attacks (TIAs) or acute ischemic stroke underwent CA ultrasonography for the examination of the MIC. Patients with CA stenosis greater than 50% were followed up until they underwent carotid endarterectomy or CA angioplasty and stent placement. If neither of these procedures were used, the patients were followed up at 90 days. Chi-square and Mann-Whitney tests were performed to compare the categorical and continuous demographic data and risk factors. The effect of the MIC on the rate of recurrent cerebral ischemia was examined using Kaplan-Meier and univariate Cox regression analyses.

Results

One hundred and fifteen patients had CA stenosis greater than 50%. Among these 115 patients, 58 with a total of 59 CA stenoses had MIC. Twenty-four recurrent ischemic events were associated with MIC, whereas only 6 such events occurred in the absence of MIC. The MIC decreased event-free survival (log-rank test = 15.8, p < 0.001); univariate Cox analysis confirmed that MIC increased the risk of a recurrent ischemic event (HR 5.12, 95% CI 2.08–12.58; p < 0.001).

Conclusions

The MIC is one of the findings of vulnerable plaques. The MIC is more useful in predicting the recurrence of TIAs or ischemic events in patients with symptomatic CA stenosis.

The role of embolic protection devices during carotid stenting prior to cardiac surgery in asymptomatic patients: empty filters?

OBJECTIVES

The purpose of this study was to analyze the debris captured in the distal protection filters used during carotid artery stenting (CAS).

BACKGROUND

CAS is an option available to high-risk patients requiring revascularization. Filters are suggested for optimal stroke prevention during CAS.

METHODS

From May 2005 to June 2007, filters from 59 asymptomatic patients who underwent CAS were collected and sent to a specialized laboratory for light-microscope and histological analysis. Peri- and postprocedural outcomes were assessed during 1-year follow-up.

RESULTS

On the basis of biomedical imaging of the filter debris, the captured material could not be identified as embolized particles from the carotid plaque. On histological analysis the debris consisted mainly of red blood cell aggregates and/ or platelets, occasionally accompanied by granulocytes. We found no consistent histological evidence of embolized particles originating from atherosclerotic plaques. Post-procedure, three neurological events were reported: two (3.4%) transient ischemic attacks (TIA) and one (1.7%) ipsilateral minor stroke.

CONCLUSION

The filters used during CAS in asymptomatic patients planned for cardiac surgery often remained empty. These findings may be explained by assuming that asymptomatic patients feature a different atherosclerotic plaque composition or stabilization through antiplatelet medication. Larger, randomized trials are clearly warranted, especially in the asymptomatic population.

Comparing the embolic potential of open and closed cell stents during carotid angioplasty and stenting

OBJECTIVE

We sought to determine the effects of open (O) and closed (C) cell stents on the size and number of embolic particles generated during carotid artery stenting (CAS) and assess the impact on outcome.

METHODS

Embolic debris from carotid filters after CAS was analyzed using photomicroscopy and imaging software. Patient comorbidities, preoperative cerebrovascular symptoms, stent type, and outcomes (perioperative major adverse events) were examined.

RESULTS

Carotid filters from 173 consecutive CAS procedures (O, 125 and C, 48) were reviewed. The mean age was 70.9 ± 9.2 years; 58% were men. Mean stenosis was 88.2% ± 8.1%; 36.6% had neurological symptoms preprocedurally. There was no difference in preoperative symptoms between the two groups (O, 38.7% vs C, 31.3%; P = not significant [NS]). However, closed cell stent use was associated with higher degree of stenosis (O, 87.2% ± 8.0% vs C, 90.6% ± 7.8%; P = .01), an older age (O, 70.0 ± 8.6 years vs C, 73.4 ± 10.2 years; P = .03), and peripheral arterial disease (21.1% vs 43.5%; P = .01). A larger mean particle size was observed in patients treated with open cell stents compared to closed cell stents (O, 416.5 ± 335.7 μm vs C, 301.1 ± 251.3 μm; P = .03). There was no significant difference in the total number of particles (O, 13.8 ± 21.5 vs C, 17.6 ± 19.9; P = NS), periprocedural stroke (P = NS), and major adverse events between the two groups (P = NS).

CONCLUSIONS

Open cell stents are associated with a larger mean particle size compared to closed cell stents. No impact on procedural outcomes based on stent type was observed.

Clinical implications of internal carotid artery flow impairment caused by filter occlusion during carotid artery stenting

BACKGROUND AND PURPOSE

Membrane filters are EPDs, which preserve ICA flow during CAS. However, ICA flow arrest may occur with filter use. This report describes the angiographic, clinical, and histopathologic features of the filter occlusion.

MATERIALS AND METHODS

Sixty-one consecutive patients with cervical carotid stenosis treated by CAS by using a single type of filter device were evaluated. All patients were on dual antiplatelet treatment and fully heparinized. Prestent dilation was performed in all patients. Poststent dilation was performed in 15 patients. Control angiograms were obtained and evaluated after each step of the CAS procedure. All filters were inspected for debris, and if present, histology was obtained.

RESULTS

CAS was successfully performed in all cases with <20% residual stenosis. Filter occlusion occurred in 6 patients (9.8%). It developed immediately after stent deployment in 4, and after a second prestent dilation in 2. Five of the 6 had severe carotid stenosis. In all patients, filter withdrawal led to immediate and complete restoration of ICA flow. In 1 patient, acute embolic M1 occlusion occurred immediately after filter withdrawal but was successfully treated with thrombolysis. None of filter-occlusion group had permanent neurologic deficits. Gross and microscopic examinations demonstrated that the pores of the filters were occluded mainly by fibrin. Postoperative diffusion MR imaging revealed no difference between filter-occlusion and non-filter-occlusion groups.

CONCLUSIONS

ICA flow arrest due to filter occlusion during CAS is relatively common and occurs more frequently in severe stenosis. It resolves rapidly after filter removal and does not appear to worsen outcome.

Routine aspiration method during filter-protected carotid stenting: histological evaluation of captured debris and predictors for debris amount

BACKGROUND

A routine aspiration method in filter-protected carotid artery stenting (CAS) has been reported recently in which the proximal internal carotid artery (ICA) blood column was aspirated using an aspiration catheter after postdilatation regardless of flow state on digital subtraction angiography. We examined the debris particles captured by this method.

METHODS

The routine aspiration method was used in 71 CAS procedures. In two procedures, captured debris particles were examined histologically. In the remaining 69 procedures, the size and number of debris particles were measured under a stereoscopic microscope, and then relationships between the amount of debris particles and clinical variables were evaluated using multivariate regression analysis.

RESULTS

Histologically, the captured debris contained platelet-precipitating, thrombotic, lipid-rich fibrous and calcified material. The number of debris particles ≥1 mm was 19.6 ± 12.1 (mean ± SD) in 60 procedures with normal flow and 25.9 ± 17.2 (mean ± SD) in 9 procedures with slow/stop flow. Multivariate regression analysis demonstrated that extension of a proximal ICA angulation was an independent predictor of the amount of debris particles with a maximum diameter of either ≥1 mm or <1 mm but ≥0.5 mm (p < 0.05).

CONCLUSIONS

The captured debris appeared to originate from atheromatous plaques. If the routine aspiration method had not been used in the present series, the debris might have migrated into intracerebral arteries. Restriction of the extension of a proximal ICA angulation might reduce the amount of debris associated with CAS, especially when the proximal ICA angulation is pronounced.

[Filter content after carotid angioplasty and stenting: relation to ischemic lesions in diffusion-weighted imaging]

OBJECTIVES

To evaluate the relation between the material retrieved from distal filters after carotid angioplasty and stenting and the development of ischemic brain lesions in diffusion-weighted imaging (DWI). To determine the influence of demographic, clinical, and procedural variables in the pathogenesis of emboli and in ischemia after carotid angioplasty and stenting.

MATERIAL AND METHODS

We submitted the contents of the filters of 76 patients (60 men; mean age, 68.39 years; range, 46-82) who had undergone angioplasty and stenting for severe stenosis of the internal carotid artery for histologic analysis evaluating volume (< 1 λ = 0.001 ml = 1 μl; 1-10 λ; and > 10 λ) and the composition of the particles. All patients underwent DWI before and 24 hours after the procedure; we recorded whether lesions appeared and their number, size, and distribution. We correlated the findings with demographic, clinical, and procedural variables.

RESULTS

Symptoms were present before the procedure in 58 (76.3%) patients. Particles were present in 49 (64.5%) of the filters; most particles (77.5%) were 1 λ with a predominance of fibrin-platelet aggregates, cell remnants, and cholesterol crystals. DWI after the procedure detected lesions in 12 (15.8%) patients. We found no statistically significant correlation between filter contents and lesion detection after the procedure or between filter contents and other variables.

CONCLUSIONS

Ischemia after carotid angioplasty and stenting does not depend solely on the embolic load and its nature. We consider that the lower prevalence of postprocedural lesions in our series compared to others suggests that appropriate patient selection and experience minimize the negative influence of some variables like age in their development.

Carotid artery disease and stenting: insights from recent clinical trials

OPINION STATEMENT

Cerebrovascular disease remains a leading cause of morbidity, mortality, and health care expenditure in the United States. Approximately 80% of strokes are ischemic in origin, with 20% to 25% due to atherosclerotic disease of the carotid artery. It is well established that untreated, symptomatic carotid stenosis confers a 25% risk of stroke within 2 years, and that asymptomatic carotid stenosis > 60% is associated with an 11% stroke risk at 5 years. Over the past six decades, surgical revascularization with carotid endarterectomy, when performed by experienced surgeons, has been demonstrated to be effective in reducing stroke risk in patients with severe stenosis. During the same time, medical therapy has improved considerably, and endovascular therapy with carotid angioplasty and stenting has emerged as an important alternative strategy that may play a significant role in reducing the risk of stroke in patients with carotid disease. In this review, we examine the current evidence regarding optimal medical therapy, endarterectomy, and stenting for the management of patients with carotid stenosis. Armed with these data, we may tailor our approach to optimize care based on patient- and lesion-specific considerations.

Routine Use of Debris Aspiration Before Retrieval of Distal Filter Protection Devices in Carotid Arterial Stenting: Analysis of Captured Debris and Evaluation of Clinical Results

BACKGROUND:

Distal filter protection allows for continuous cerebral perfusion during carotid artery stenting (CAS), although a higher risk of debris migrating into the cerebral arteries compared with other protection systems has been reported.

OBJECTIVE:

To improve the extent of debris capture, we used routine aspiration of blood located proximal to the filter in the internal carotid artery blood column before retrieval of the filter device.

METHODS:

Of 71 CAS procedures with distal filter protection, routine aspiration was performed in 41 procedures. The size and number of debris particles in each aspirated blood sample were measured under a stereoscopic microscope in 30 consecutive procedures with routine aspiration. Occurrence of periprocedural neurological events was compared between 41 procedures with routine aspiration and the other 30 without routine aspiration.

RESULTS:

In the aspirated blood, debris particles ≥500 μm and ≥1000 μm in the longest diameter were observed in 30 (100%) and 28 (93.3%) procedures, respectively. The number of particles ≥1000 μm was significantly larger in the second through fourth blood aspirates vs the first aspirate (P &lt; .05). Occurrence of periprocedural neurological events was significantly less frequent in the routine aspiration group (0 of 41 procedures) than in the conventional method group (7 of 30 procedures) (P &lt; .05).

CONCLUSION:

The use of routine aspiration during CAS with distal filter protection possibly reduced periprocedural neurological events by increasing the proportion of debris captured. To improve the capture of debris particles, at least 4 repeated aspirations are advisable during each CAS procedure.

Classification for carotid artery stenting complications: manifestation, management, and prevention

Carotid artery stenting is a rapidly evolving method for treating carotid artery disease. Various intraprocedural and postprocedural complications have been reported in the literature. However, the absence of a unified classification scheme for these complications makes it difficult, if not impossible, to study their precise incidence, predictors, and management. The aim of this article is to propose the first joint classification of periprocedural complications, to analyze their incidence and etiology, and suggest possible ways to manage and prevent them. This classification is intended to be used as a common platform for prompt recognition, evaluation, treatment, and universal study of the complications during carotid stenting procedures. For this purpose, the opinions of the major experts on carotid interventions worldwide were merged with all the available information reported in the English-language literature to present as accurately as possible the management and prevention of carotid stenting complications according to this proposed classification.

Assessment of necrotic core with intraplaque hemorrhage in atherosclerotic carotid artery plaque by MR imaging with 3D gradient-echo sequence in patients with high-grade stenosis

Object

The aim of this study was to assess the histopathological differences between advanced atherosclerotic carotid artery (CA) plaques with signal hyperintensity on T1-weighted MR images and those without, focusing on necrotic core size and intraplaque hemorrhage (IPH).

Methods

Thirty-five patients scheduled for carotid endarterectomy underwent preoperative CA MR imaging using 3D inversion-recovery-based T1-weighted imaging (magnetization-prepared rapid acquisition gradient-echo [MPRAGE]). The signal intensity of the CA plaque on MPRAGE sequences was classified as “high” when the intensity was more than 200% that of adjacent muscle. A total of 96 axial MR images obtained in 35 patients were compared with corresponding histological sections from 36 excised specimens. The area of the necrotic core in histological sections was compared between specimens with and without high signal intensity on MPRAGE sequences. The IPH was histopathologically graded according to the size of the area positive for glycophorin A as revealed by immunohistochemical staining. The difference between plaques with and without high signal intensity was investigated with respect to the degree of IPH. The relationship of the severity of IPH to size of the necrotic core was also evaluated.

Results

The area of the necrotic core in plaques with high signal intensity on MPRAGE sequences was significantly larger than that in plaques without high signal intensity (median 51.2% [interquartile range 43.3–66.8%] vs 49.0% [33.2–57.6%], p = 0.029). Carotid artery plaques with high signal intensity had significantly more severe IPH than plaques with lower signal intensity (p < 0.0001). The severity of IPH was significantly associated with the size of the necrotic core (p < 0.0001).

Conclusions

Atherosclerotic CA plaques with high signal intensity on MPRAGE sequences had large necrotic cores with IPH in patients with high-grade stenosis; MPRAGE is useful for the evaluation of CA plaque progression.

Simple immersion of filter devices into an urokinase solution prevents fibrin net formation during carotid artery stenting

Slow-flow phenomenon is frequently observed during carotid artery stenting (CAS) with a filter embolic protection device. It results in technical difficulties and can lead to adverse neurological events. Flow impairment is thought to be caused by plaque entrapped by the filter and/or blood coagulation on the filter. Characteristics of heparin- or urokinase-treated polyurethanes were analyzed by surface plasmon resonance, and the fibrinolytic activity of the urokinase-treated filter of Angioguard XP was estimated by the fibrin plate assay. A filter membrane of Angioguard XP protection device was treated with a heparin or urokinase solution. In clinical studies, six and nine patients were treated by CAS using Angioguard XP modified with heparin and urokinase, respectively. Filter membranes were examined by scanning electron microscopy (SEM). From in vitro studies, it appeared that urokinase adsorbed and remained on the Angioguard XP filter, and its fibrinolytic activity was demonstrated even after washing with saline; heparin, however, was easily washed out from the surface. From clinical study, some filter pores were obstructed in all six patients in the heparin group and in three patients in the urokinase group. Fibrin net was found on the filter in five of six patients in the heparin group and in one of nine patients in the urokinase group. Treatment of an Angioguard XP filter with a urokinase solution is effective in preventing pore occlusion and may reduce occurrence of the slow-flow phenomenon.