In vitro comparison of four cerebral protection filters for preventing human plaque embolization during carotid interventions

Transradial carotid artery stenting using double layer micromesh stent and novel post-dilation balloon with integrated embolic protection

OBJECTIVES

The highest rate of embolization during carotid artery stenting occurs during post-dilation. We evaluated the ability of the Paladin system (Contego Medical, Raleigh, NC), a novel PTA balloon with an integrated 40-ɥm pore filter, to collect microemboli that may pass into the cerebral circulation when used during post-dilation.

METHODS

25 symptomatic patients underwent transradial CAS using the Paladin system in conjunction with the Roadsaver (Terumo Corporation, Tokyo, Japan) micromesh stent. No additional embolic protection was used. The Paladin filters were collected following the procedure and preserved in formalin for histological analysis. The contents were evaluated for particle count and size. Subjects were followed for 30 days and evaluated for major cardiac adverse events (death, stroke and MI). Secondary endpoints included procedure success, device success, access site complications according to EASY score classification, major vascular or ischemic complications at follow up and in-stent restenosis rate evaluated with duplex ultrasound.

RESULTS

Mean age of patients was 68,5 years. Type 2 aortic arch was present in 77 % of patients and type 1 and type 3 in 12 % and 11 % of patients respectively. Procedural and device success was obtained in all cases without complications. The 30-day MAE rate was 0 %. Twenty-three filters underwent histological analysis. Microscopic debris was present in 100 % of filters, and 75 % of particles were less than 100ɥm in size. The mean number of particles per filter was 3352 ± 1567 (IQR 4300-2343), and the mean number of particles between 40-100ɥm per filter was 2499 ± 1240 (IQR 3227-1575).

CONCLUSION

CAS through radial approach can be safely and effectively performed using the IEP technology Paladin device and double-layer micromesh Roadsaver stent. This strategy can simplify the procedure and decrease peri-procedural complications and procedural time.

Brazilian Angiology and Vascular Surgery Society Guidelines for the treatment of extracranial cerebrovascular disease

Extracranial cerebrovascular disease has been the subject of intense research throughout the world, and is of paramount importance for vascular surgeons. This guideline, written by the Brazilian Society of Angiology and Vascular Surgery (SBACV), supersedes the 2015 guideline. Non-atherosclerotic carotid artery diseases were not included in this document. The purpose of this guideline is to bring together the most robust evidence in this area in order to help specialists in the treatment decision-making process. The AGREE II methodology and the European Society of Cardiology system were used for recommendations and levels of evidence. The recommendations were graded from I to III, and levels of evidence were classified as A, B, or C. This guideline is divided into 11 chapters dealing with the various aspects of extracranial cerebrovascular disease: diagnosis, treatments and complications, based on up-to-date knowledge and the recommendations proposed by SBACV.

Association of stroke or death with severity of carotid lesion calcification in patients undergoing carotid artery stenting

OBJECTIVE

Carotid artery stenting (CAS) for heavily calcified lesions is controversial due to concern for stent failure and increased perioperative stroke risk. However, the degree to which calcification affects outcomes is poorly understood, particularly in transcarotid artery revascularization (TCAR). With the precipitous increase in TCAR use and its expansion to standard surgical-risk patients, we aimed to determine the impact of lesion calcification on CAS outcomes to ensure its safe and appropriate use.

METHODS

We identified patients in the Vascular Quality Initiative who underwent first-time transfemoral CAS (tfCAS) and TCAR between 2016 and 2021. Patients were stratified into groups based on degree of lesion calcification: no calcification, 1% to 50% calcification, 51% to 99% calcification, and 100% circumferential calcification or intraluminal protrusion. Outcomes included in-hospital and 1-year composite stroke/death, as well as individual stroke, death, and myocardial infarction outcomes. Logistic regression was used to evaluate associations between degree of calcification and these outcomes.

RESULTS

Among 21,860 patients undergoing CAS, 28% patients had no calcification, 34% had 1% to 50% calcification, 35% had 51% to 99% calcification, and 3% had 100% circumferential calcification/protrusion. Patients with 51% to 99% and circumferential calcification/protrusion had higher odds of in-hospital stroke/death (odds ratio [OR], 1.3; 95% confidence interval [CI], 1.02-1.6; P = .034; OR, 1.9; 95% CI, 1.1-2.9; P = .004, respectively) compared with those with no calcification. Circumferential calcification was also associated with increased risk for in-hospital myocardial infarction (OR, 3.5; 95% CI, 1.5-8.0; P = .003). In tfCAS patients, only circumferential calcification/protrusion was associated with higher in-hospital stroke/death odds (OR, 2.0; 95% CI, 1.2-3.4; P = .013), whereas for TCAR patients, 51% to 99% calcification was associated with increased odds of in-hospital stroke/death (OR, 1.5; 95% CI, 1.1-2.2; P = .025). At 1 year, circumferential calcification/protrusion was associated with higher odds of ipsilateral stroke/death (12.4% vs 6.6%; hazard ratio, 1.64; P = .002).

CONCLUSIONS

Among patients undergoing CAS, there is an increased risk of in-hospital stroke/death for lesions with >50% calcification or circumferential/protruding plaques. Increasing severity of carotid lesion calcification is a significant risk factor for stroke/death in patients undergoing CAS, regardless of approach.

PERFORMANCE 1 study: Novel carotid stent system with integrated post-dilation balloon and embolic protection device

OBJECTIVES

The PERFORMANCE I study was designed to evaluate the safety and feasibility of the Neuroguard IEP® System, a novel carotid stent system with an integrated embolic filter and post-dilatation balloon, to treat clinically significant carotid artery stenosis.

BACKGROUND

The risk of major adverse events during carotid artery stenting is comparable to carotid endarterectomy, however, the risk of minor stroke remains higher with stenting.

METHODS

In total, 67 patients undergoing carotid artery stenting were enrolled at nine centers in Europe. Follow-up assessments included neurological exams, duplex ultrasound, 12-lead electrocardiogram, and cardiac enzyme analysis. The primary endpoint was the 30-day composite rate of stroke, death, and myocardial infarctions versus a prespecified performance goal. Secondary endpoints included procedure success, device success, and target lesion revascularization.

RESULTS

The study population was predominantly male (74.6%) with a mean age of 69.3 ± 8.9 years and 67% of subjects met at least one criterion placing them at an elevated risk for adverse events following carotid endarterectomy. All patients were treated successfully with the study device. There were no deaths or strokes within 30 days of the index procedure. One subject (1.5%) experienced a non-ST elevation myocardial infarction at day 17. The primary endpoint was met with a 30-day major adverse events rate of 1.5% (1/67). Through 12-month follow-up, there were no strokes, neurological deaths, target lesion revascularizations, or instances of in-stent-restenosis.

CONCLUSIONS

Results from this study demonstrate the Neuroguard IEP system is safe and feasible with a stroke/death rate of 0% at 30 days. A large pivotal study is currently underway.

Transcarotid Artery Revascularization: Is It Better than Carotid Endarterectomy?

Transcarotid artery revascularization (TCAR) is a novel carotid stenting method that avoids the manipulation of the aortic arch and uses a flow-reversal neuroprotection system that effectively reduces the risk of embolic events during carotid intervention. Studies have shown a lower risk of stroke or death compared with the transfemoral carotid stenting approach, and an equivalent risk of stroke or death compared with traditional carotid endarterectomy. TCAR has added benefits of lower risk of myocardial infarction, cranial nerve injuries, and shorter operative times compared with endarterectomy. TCAR has become widely adopted by vascular surgeons in the United States for the treatment of patients with high-risk medical comorbidities and those with challenging surgical anatomy.

Non-protected carotid artery stenting for symptomatic carotid stenosis in low resource settings

Background

The use of a distal cerebral protection device during extracranial carotid artery stenting is still a matter of debate. The aim of this work was to evaluate the safety of performing carotid artery stenting procedure without the use of cerebral protection device in patients with symptomatic carotid stenosis. A retrospective study was performed during the period from September 2015 till March 2020 including 91 patients with symptomatic carotid artery stenosis. All patients were treated with a single stent type (Wall stent® - Boston scientific) without the use of cerebral protection device. Pre- and post-procedural clinical assessment with the national institute of health stroke scale (NIHSS). Post procedure brain diffusion-weighted magnetic resonance imaging (DW-MRI) if clinically indicated within 24 h was used to determine periprocedural cerebral embolization.

Results

A low complication rate was found as only one case (1%) showed mild deterioration in NIHSS and new acute cerebral emboli were detected with brain DW-MRI.

Conclusion

Carotid artery stenting can be performed safely without the use of cerebral protection device.

Primary mechanism of stroke reduction in transcarotid artery revascularization is dynamic flow reversal

OBJECTIVE

Recent studies have suggested that the low risk of stroke and death associated with transcarotid artery revascularization (TCAR) is partially attributable to a robust dynamic flow reversal system and the avoidance of the atherosclerotic aortic arch during stenting. However, the benefits of flow reversal compared with distal embolic protection (DEP) in reducing stroke or death in TCAR have not been studied.

METHODS

All patients undergoing carotid artery stenting (CAS) via the transcarotid route with either dynamic flow reversal (TCAR) or DEP (TCAS-DEP) in the Vascular Quality Initiative from September 2016 to November 2019 were analyzed. Both multivariable logistic regression and nearest neighbor propensity score-matched analysis were performed to explore the differences in outcomes between the two procedures. The primary outcome was in-hospital stroke or death. The secondary outcomes were stroke, death, myocardial infarction (MI), and the composite of stroke, death, and MI. A secondary analysis was performed to compare transcarotid stenting with DEP vs transfemoral CAS with DEP to evaluate the effects of crossing the aortic arch.

RESULTS

A total of 8426 patients were identified (TCAS-DEP, n = 287; 3.4%). TCAR was associated with a lower risk of in-hospital stroke or death (1.6% vs 5.2%; odds ratio [OR], 0.35; 95% confidence interval [CI], 0.20-0.64; P = .001), stroke (1.4% vs 4.2%; OR, 0.37; 95% CI, 0.20-0.68; P = .002), and stroke/death/MI (2.0% vs 5.2%; OR, 0.41; 95% CI, 0.23-0.71; P = .001) compared with TCAS-DEP. Among the 274 pairs of patients identified with propensity score matching, TCAR was associated with a lower risk of stroke/death (1.1% vs 4.7%; risk ratio [RR], 0.23; 95% CI, 0.06-0.81; P = .021) and stroke (0.4% vs 4.0%; RR, 0.09; 95% CI, 0.01-0.70; P = .006) compared with TCAS-DEP but no differences in stroke/death/MI (1.8% vs 4.7%; RR, 0.38; 95% CI, 0.15-1.02; P = .077). The secondary analysis found no differences in stroke between TCAS-DEP and transfemoral CAS with DEP (4.9% vs 3.7%; RR, 1.3; 95% CI, 0.36-1.63; P = .65).

CONCLUSIONS

Compared with TCAS-DEP, TCAR was associated with a lower risk of perioperative stroke or death and stroke. This finding implies that dynamic flow reversal might provide better neuroprotection than does a distal embolic filter in reducing the perioperative risk of stroke. Avoiding the aortic arch did not confer any reduction in the stroke rate. The present findings serve to separate the clinical benefit of dynamic flow reversal from that of avoiding the aortic arch during TCAR.

Permanent Bilateral Carotid Filters for Stroke Prevention in Atrial Fibrillation

Purpose of Review

A novel permanent carotid filter device for percutaneous implantation was developed for the purpose of stroke prevention. In this review, we cover rationale, existing preclinical and clinical data, and potential future directions for research using such a device.

Recent Findings

The Vine™ filter was assessed for safety in sheep and in 2 observational human studies, the completed CAPTURE 1 (n = 25) and the ongoing CAPTURE 2 (planned n = 100). CAPTURE 1 has shown high procedural and long-term implant safety. A control group was not available for comparison.

Summary

A mechanical filter for permanent stroke prevention can be implanted bilaterally in the common carotid artery safely and efficiently. A randomized trial is planned for 2021 (n = 3500, INTERCEPT) to demonstrate superiority of a filter + anticoagulation strategy over anticoagulation alone in patients at high risk for ischemic stroke.

Double Filtration During Carotid Artery Stenting Using a Novel Post-Dilation Balloon With Integrated Embolic Protection

OBJECTIVES

This study evaluated the safety and performance of the Paladin System, a novel angioplasty balloon with an integrated embolic protection filter designed to increase embolic protection during post-dilation.

BACKGROUND

The risk of major adverse events during carotid artery stenting (CAS) is equivalent to carotid endarterectomy. However, the risk of minor stroke remains higher with CAS. Much of this risk occurs during post-stent dilation.

METHODS

A total of 106 patients were enrolled in 5 centers in Germany. The study's primary endpoint was all-cause death, myocardial infarction, and stroke at 30 days post-procedure. Pre- and post-procedural diffusion-weighted magnetic resonance imaging evaluated new ischemic lesions in 30 subjects. Filter histomorphometric analysis was performed in 23 patients. Retrospective analyses compared outcome rates to historical controls.

RESULTS

Device and procedural success rates were 100%. The combined major adverse event rate (death, myocardial infarction, and stroke) at discharge and at 30 days was 0% and 1.0%, respectively. The single adverse event was a stroke, which occurred at day 12 and was believed unrelated to the device or procedure. New ischemic lesions were found in 11 (36.7%) patients in the diffusion-weighted magnetic resonance imaging subset. New ipsilateral lesions were seen in 9 (30.0%) patients. Mean lesion volume per patient was 0.010 cm³. Debris was present in all filters, and approximately 90% of captured particles were <100 μm.

CONCLUSIONS

Use of the Paladin System for post-stent dilation during CAS appears safe, and it may effectively decrease the number of embolic particles reaching the brain, which may help reduce the risk of procedure-related stroke. (A Multi-Center Study to Evaluate Acute Safety and Clinical Performance of Paladin® Carotid Post-Dilation Balloon System With Integrated Embolic Protection; NCT02501148).

Association of Transcarotid Artery Revascularization vs Transfemoral Carotid Artery Stenting With Stroke or Death Among Patients With Carotid Artery Stenosis

Importance

Several trials have observed higher rates of perioperative stroke following transfemoral carotid artery stenting compared with carotid endarterectomy. Transcarotid artery revascularization with flow reversal was recently introduced for carotid stenting. This technique was developed to decrease stroke risk seen with the transfemoral approach; however, its outcomes, compared with transfemoral carotid artery stenting, are not well characterized.

Objective

To compare outcomes associated with transcarotid artery revascularization and transfemoral carotid artery stenting.

Design, Setting, and Participants

Exploratory propensity score-matched analysis of prospectively collected data from the Vascular Quality Initiative Transcarotid Artery Surveillance Project and Carotid Stent Registry of asymptomatic and symptomatic patients in the United States and Canada undergoing transcarotid artery revascularization and transfemoral carotid artery stenting for carotid artery stenosis, from September 2016 to April 2019. The final date for follow-up was May 29, 2019.

Exposures

Transcarotid artery revascularization vs transfemoral carotid artery stenting.

Main Outcomes and Measures

Outcomes included a composite end point of in-hospital stroke or death, stroke, death, myocardial infarction, as well as ipsilateral stroke or death at 1 year. In-hospital stroke was defined as ipsilateral or contralateral, cortical or vertebrobasilar, and ischemic or hemorrhagic stroke. Death was all-cause mortality.

Results

During the study period, 5251 patients underwent transcarotid artery revascularization and 6640 patients underwent transfemoral carotid artery stenting. After matching, 3286 pairs of patients who underwent transcarotid artery revascularization or transfemoral carotid artery stenting were identified (transcarotid approach: mean [SD] age, 71.7 [9.8] years; 35.7% women; transfemoral approach: mean [SD] age, 71.6 [9.3] years; 35.1% women). Transcarotid artery revascularization was associated with a lower risk of in-hospital stroke or death (1.6% vs 3.1%; absolute difference, -1.52% [95% CI, -2.29% to -0.75%]; relative risk [RR], 0.51 [95% CI, 0.37 to 0.72]; P < .001), stroke (1.3% vs 2.4%; absolute difference, -1.10% [95% CI, -1.79% to -0.41%]; RR, 0.54 [95% CI, 0.38 to 0.79]; P = .001), and death (0.4% vs 1.0%; absolute difference, -0.55% [95% CI, -0.98% to -0.11%]; RR, 0.44 [95% CI, 0.23 to 0.82]; P = .008). There was no statistically significant difference in the risk of perioperative myocardial infarction between the 2 cohorts (0.2% for transcarotid vs 0.3% for the transfemoral approach; absolute difference, -0.09% [95% CI, -0.37% to 0.19%]; RR, 0.70 [95% CI, 0.27 to 1.84]; P = .47). At 1 year using Kaplan-Meier life-table estimation, the transcarotid approach was associated with a lower risk of ipsilateral stroke or death (5.1% vs 9.6%; hazard ratio, 0.52 [95% CI, 0.41 to 0.66]; P < .001). Transcarotid artery revascularization was associated with higher risk of access site complication resulting in interventional treatment (1.3% vs 0.8%; absolute difference, 0.52% [95% CI, -0.01% to 1.04%]; RR, 1.63 [95% CI, 1.02 to 2.61]; P = .04), whereas transfemoral carotid artery stenting was associated with more radiation (median fluoroscopy time, 5 minutes [interquartile range {IQR}, 3 to 7] vs 16 minutes [IQR, 11 to 23]; P < .001) and more contrast (median contrast used, 30 mL [IQR, 20 to 45] vs 80 mL [IQR, 55 to 122]; P < .001).

Conclusions and Relevance

Among patients undergoing treatment for carotid stenosis, transcarotid artery revascularization, compared with transfemoral carotid artery stenting, was significantly associated with a lower risk of stroke or death.

In-hospital outcomes of transcarotid artery revascularization and carotid endarterectomy in the Society for Vascular Surgery Vascular Quality Initiative

OBJECTIVE

Transcarotid artery revascularization (TCAR) with flow reversal offers a less invasive option for carotid revascularization in high-risk patients and has the lowest reported overall stroke rate for any prospective trial of carotid artery stenting. However, outcome comparisons between TCAR and carotid endarterectomy (CEA) are needed to confirm the safety of TCAR outside of highly selected patients and providers.

METHODS

We compared in-hospital outcomes of patients undergoing TCAR and CEA from January 2016 to March 2018 using the Society for Vascular Surgery Vascular Quality Initiative TCAR Surveillance Project registry and the Society for Vascular Surgery Vascular Quality Initiative CEA database, respectively. The primary outcome was a composite of in-hospital stroke and death.

RESULTS

A total of 1182 patients underwent TCAR compared with 10,797 patients who underwent CEA. Patients undergoing TCAR were older (median age, 74 vs 71 years; P < .001) and more likely to be symptomatic (32% vs 27%; P < .001); they also had more medical comorbidities, including coronary artery disease (55% vs 28%; P < .001), chronic heart failure (20% vs 11%; P < .001), chronic obstructive pulmonary disease (29% vs 23%; P < .001), and chronic kidney disease (39% vs 34%; P = .001). On unadjusted analysis, TCAR had similar rates of in-hospital stroke/death (1.6% vs 1.4%; P = .33) and stroke/death/myocardial infarction (MI; 2.5% vs 1.9%; P = .16) compared with CEA. There was no difference in rates of stroke (1.4% vs 1.2%; P = .68), in-hospital death (0.3% vs 0.3%; P = .88), 30-day death (0.9% vs 0.4%; P = .06), or MI (1.1% vs 0.6%; P = .11). However, on average, TCAR procedures were 33 minutes shorter than CEA (78 ± 33 minutes vs 111 ± 43 minutes; P < .001). Patients undergoing TCAR were also less likely to incur cranial nerve injuries (0.6% vs 1.8%; P < .001) and less likely to have a postoperative length of stay >1 day (27% vs 30%; P = .046). On adjusted analysis, there was no difference in terms of stroke/death (odds ratio, 1.3; 95% confidence interval, 0.8-2.2; P = .28), stroke/death/MI (odds ratio, 1.4; 95% confidence interval, 0.9-2.1, P = .18), or the individual outcomes.

CONCLUSIONS

Despite a substantially higher medical risk in patients undergoing TCAR, in-hospital stroke/death rates were similar between TCAR and CEA. Further comparative studies with larger samples sizes and longer follow-up will be needed to establish the role of TCAR in extracranial carotid disease management.

Recent advances in the treatment of carotid artery disease

Transfemoral carotid stenting has struggled to become a suitable alternative to carotid endarterectomy for the treatment of carotid disease because of higher perioperative stroke risks, even with use of embolic protection devices. To reduce the perioperative stroke rates associated with carotid stenting, several advancements in stent design, embolic protection systems, and technical approaches have been developed. Transcarotid artery revascularization (TCAR) was also recently introduced as a novel carotid artery stenting option which circumvents several of the high embolic-risk maneuvers found in transfemoral carotid stenting and employs a flow reversal system that provides continuous embolic protection throughout the procedure. Early results from this technique have shown low stroke/death rates comparable to carotid endarterectomy while maintaining the minimally invasive benefits of carotid stenting. TCAR has a strong potential to become the preferred method of carotid stenting in the near future and may challenge carotid endarterectomy as the preferred carotid artery revascularization method.

Efficiency test of current carotid embolic protection devices

Embolic protection devices were developed to reduce the risk of stroke during carotid artery stenting. The aim of this study was to test the capture efficiency of five embolic protection devices under reproducible in vitro conditions. The setup consisted of silicone tubes representing the vessel modeling round and oval cross sections. Spherical polystyrene particles (150 μm, COOH-coating) were used to simulate the plaque. The particles were inserted in a clean water circuit and either captured by the device or collected in a glass filter. The missed particles were counted by laser obscuration as a measure of device leakage. The systems Angioguard RX, RX Accunet, FiberNet, FilterWire EZ and EmboshieldNAV were analyzed. At the round cross section, FilterWire EZ demonstrated the highest capture efficiency (0% of missed particles) and RX Accunet the lowest, at 34%. The amount of leaked particles increased to 22% for FilterWire EZ and 89% for Angioguard RX during the test with the oval cross profile.

Transcervical Carotid Stenting With Dynamic Flow Reversal Demonstrates Embolization Rates Comparable to Carotid Endarterectomy

PURPOSE

To evaluate a series of patients treated electively with carotid endarterectomy (CEA), transfemoral carotid artery stenting with distal filter protection (CASdp), and transcervical carotid stenting with dynamic flow reversal (CASfr) monitored continuously with transcranial Doppler (TCD) during the procedure to detect intraoperative embolization rates.

METHODS

Thirty-four patients (mean age 67.6 years; 24 men) with significant carotid stenosis underwent successful TCD monitoring during the revascularization procedure (10 CEA, 8 CASdp, and 16 CASfr). Ipsilateral microembolic signals were segregated into 3 phases: preprotection (until internal carotid artery cross-shunted or clamped if no shunt was used, filter deployed, or flow reversal established), protection (until clamp/shunt was removed, filter retrieved, or antegrade flow reestablished), and postprotection (after clamp/shunt or filter removal or restoration of normal flow).

RESULTS

CASdp showed higher embolization rates than CEA or CASfr in the preprotection phase (p<0.001). In the protection phase, CASdp was again associated with more embolization compared with CEA and CASfr (p<0.001). In the postprotection phase, no differences between the revascularization therapies were observed. CASfr and CEA did not show significant differences in intraoperative embolization during any of the phases.

CONCLUSION

TCD recordings demonstrated a significant reduction in embolization to the brain during transcervical carotid artery stent placement with the use of dynamic flow reversal compared to transfemoral CAS using distal filters. No significant differences in microembolization could be detected between CEA and CASfr. The observed lower embolization rates and lack of adverse events suggest that transcervical CAS with dynamic flow reversal is a promising technique and may be the preferred method when performing CAS.

Impact of coexisting coronary artery disease on the occurrence of cerebral ischemic lesions after carotid stenting

Background

Coronary artery disease (CAD) may coexist with extracranial carotid artery stenosis (ECAS), but the influence of CAD on procedure-related complications after carotid artery stenting (CAS) has not been well investigated. The study aimed to determine the impact of CAD on the occurrence of peri-CAS cerebral ischemic lesions on diffusion-weighted imaging (DWI) scanning.

Methods

Coronary angiography was performed within six months before CAS. DWI scanning was repetitively done within 1 week before and after CAS. Clinical outcome measures were stroke, angina, myocardial infarction and death within 30 days.

Results

Among 126 patients (69.5±9.0 years) recruited for unilateral protected CAS, 33 (26%) patients had peri-CAS DWI-positive lesions. CAD was noted in 79% (26 in 33) and 48% (45 in 93) of patients with and without peri-CAS DWI-positive lesions (OR, 4.0; 95% CI, 1.6–10.0; P = .0018), and the number of concomitant CAD on coronary angiography was positively correlated with the risk for peri-CAS DWI-positive lesions (P = .0032). In patients with no CAD (n = 55), asymptomatic CAD (n = 41) and symptomatic CAD (n = 30), the occurrence rates of peri-CAS DWI-positive lesions were 13%, 41% and 30% (P = .0048), and the peri-CAS stroke rates were 2%, 7% and 0% (P = .2120).

Conclusions

The severity of morphological CAD and the presence of either symptomatic or asymptomatic CAD are associated with the occurrence of peri-CAS cerebral ischemic lesions.

Treatment outcomes of carotid artery stenting with two types of distal protection filter device

PURPOSE

Preventing cerebral embolism from debris produced during carotid artery stenting (CAS) is important. This study compared the treatment outcomes of CAS using two types of filter-based embolic protection devices currently in use in Japan.

MATERIALS AND METHODS

We assessed 121 consecutive cases of CAS performed with FilterWire EZ™ between July 2010 and November 2012 and 37 consecutive cases of CAS performed with the Spider FX™ between November 2012 and June 2013. A Carotid Wallstent™ was used in all cases. The incidence of positive lesions on diffusion-weighted magnetic resonance imaging (DWI) and stroke were compared between the groups.

RESULTS

Postoperative DWI-positive lesions were observed in 38 (31.4%) and 14 (37.8%) patients in the FilterWire and Spider groups, respectively. In the FilterWire group, complications were transient ischemic attacks in 3 (2.5%) patients, cerebral infarction in 2 (1.7%) patients (1 patient each with minor and major stroke), and cerebral hemorrhage due to hyperperfusion syndrome in 1 (0.8%) patient. In the Spider group, except for cerebral infarction (minor stroke) in 1 (2.7%) patient, no complications were observed. No significant differences were observed in the incidence of complications between the groups.

CONCLUSION

FilterWire EZ and Spider FX are comparable in terms of treatment outcome.

Silicone models as basic training and research aid in endovascular neurointervention--a single-center experience and review of the literature

The rapid development and wider use of neurointerventional procedures have increased the demand for a comprehensive training program for the trainees, in order to safely and efficiently perform these procedures. Artificial vascular models are one of the dynamic ways to train the new generation of neurointerventionists to acquire the basic skills of material handling, tool manipulation through the vasculature, and development of hand-eye coordination. Herein, the authors present their experience regarding a long-established training program and review the available literature on the advantages and disadvantages of vascular silicone model training. Additionally, they present the current research applications of silicone replicas in the neurointerventional arena.

Distal protection filter device efficacy with carotid artery stenting: comparison between a distal protection filter and a distal protection balloon

PURPOSE

This retrospective study aimed to compare the effectiveness of the embolization prevention mechanism of two types of embolic protection device (EPD)-a distal protection balloon (DPB) and a distal protection filter (DPF).

METHODS

Subjects were 164 patients scheduled to undergo carotid artery stenting: a DPB was used in 82 cases (DPB group) from April 2007 until June 2010, and a DPF was used in 82 cases (DPF group) from July 2010 to July 2011. Rates of positive findings on postoperative diffusion-weighted imaging (DWI) and stroke incidence were compared.

RESULTS

Positive postoperative DWI results were found in 34 cases in the DPB group (41.4 %), but in only 22 cases in the DPF group (26.8 %), and there was only a small significant difference within the DPF group. In the DPB group, there was one case of transient ischemic attack (TIA) (1.2 %) and four cases of brain infarction (2 minor strokes, 2 major strokes; 4.9 %), compared to the DFP group with one case of TIA (1.2 %) and no cases of minor or major strokes.

CONCLUSIONS

In this study, significantly lower rates of occurrence of DWI ischemic lesions and intraoperative embolization were associated with use of the DPF compared to the DPB.

Assembly of a multichannel video system to simultaneously record cerebral emboli with cerebral imaging

Stroke remains a significant risk of carotid revascularization for atherosclerotic disease. Emboli generated at the time of treatment either using endarterectomy or stent-angioplasty may progress with blood flow and lodge in brain arteries. Recently, the use of protection devices to trap emboli created at the time of revascularization has helped to establish a role for stent-supported angioplasty compared with endarterectomy. Several devices have been developed to reduce or detect emboli that may be dislodged during carotid artery stenting to treat carotid artery stenosis. A significant challenge in assessing the efficacy of these devices is precisely determining when emboli are dislodged in real time. To address this challenge, we devised a method of simultaneously recording fluoroscopic images, transcranial Doppler data, vital signs, and digital video of the patient/physician. This method permits accurate causative analysis and allows procedural events to be precisely correlated to embolic events in real time.

Determinants of embolic risk during angioplasty and stenting: neurologic symptoms and coronary artery disease increase embolic risk

BACKGROUND

Carotid angioplasty and stenting (CAS) has proven to be a potential alternative to carotid endarterectomy in the treatment of severe carotid disease. Patient selection has emerged as a means of optimizing the outcomes of CAS.

OBJECTIVE

To determine whether the presence of preprocedural neurologic symptoms and having a history of coronary artery disease (CAD) are associated with greater embolic risk during CAS through analysis of the embolic debris captured within protective filters.

METHODS

A total of 233 consecutive CAS procedures were performed between 2003 and 2009. Particles of embolic debris within the filters were quantified by photomicroscopy and video imaging software. Particulate size was determined by measuring the length along the longest axis. Preprocedural neurologic symptoms included transient ischemic attack, cerebrovascular accident, and amaurosis fugax. History of CAD included prior myocardial infarction, coronary artery bypass grafting, congestive heart failure, or abnormal stress test.

RESULTS

Of the 137 (58.8%) filters that were analyzed (mean age, 71.3 ± 9.1 years, 56.9% male), 52 (38.0%) and 80 (58.4%) filters were from symptomatic and CAD patients, respectively. Filters of symptomatic (S) patients contained both a greater number and larger mean particle size compared with those of asymptomatic (AS) patients (S: 15.8 ± 13.5 particles vs. AS: 9.8 ± 8.7 particles, P = 0.002; S: 507 ± 389 μm vs. AS: 398 ± 181 μm, P = 0.03; respectively). Filters from CAD patients also had a greater number of particles, but trended toward smaller minimum size than those in non-CAD patients (CAD: 14.4 ± 12.8 particles vs. non-CAD: 8.8 ± 7.4 particles, P = 0.002; CAD: 167 ± 172 μm vs. 228 ± 203 μm, P = 0.06).

CONCLUSIONS

These findings suggest that the presence of preprocedural neurologic symptoms and a history of CAD are associated with increased embolization during CAS. Therefore, the benefit of carotid stenting should be tempered by the potential for increased perioperative events in both symptomatic and CAD patients.

In vitro performance assessment of distal protection filters: pulsatile flow conditions

PURPOSE

To evaluate in vitro the capture efficiency of a distal protection filter (DPF) used during carotid artery stenting and examine the longitudinal vascular impedance in the presence of a DPF.

METHODS

Four approved DPFs (Spider RX, FilterWire EZ, RX Accunet, and FiberNet) were evaluated in a physiologically realistic in vitro setup. A pulsatile programmable piston pump circulated a blood analog at a time-varying flow rate representative of the human common carotid artery. A silicone carotid bifurcation having average human dimensions was used for the carotid flow model. Microspheres ranging from 40 to 900 microm were injected to simulate embolization. The longitudinal vascular impedance was calculated as the ratio of the time-varying pressure gradient across the DPF to the time-varying flow rate in the internal carotid artery.

RESULTS

RX Accunet had the highest capture efficiency (99.4%) and Spider RX the lowest (78.1%). Spider RX increased the longitudinal vascular impedance the least after deployment (+23%), while FilterWire EZ increased the longitudinal vascular impedance the least after particles were injected (+29%). FiberNet increased longitudinal vascular impedance the most (+84%).

CONCLUSION

This investigation, unique for examining the effects of physiologically realistic pulsatile flow on DPF performance, can aid in the development of future generations of novel DPFs.

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.

Vascular resistance in the carotid artery: an in vitro investigation of embolic protection filters

PURPOSE

To assess in vitro performance of four embolic protection filters (EPFs) with a varying mass of injected particles. Evaluation is based on capture efficiency, pressure gradient, flow rate, and vascular resistance.

MATERIALS AND METHODS

A bench-top flow apparatus was used for in vitro testing of four devices (Spider RX, FilterWire EZ, RX Accunet, and Emboshield). A silicone phantom with average human carotid artery dimensions and a 70% symmetric internal carotid artery (ICA) stenosis was used to model the carotid bifurcation. A blood-mimicking solution (glycerol/deionized water) was circulated at the time-averaged mean peak velocity for the common carotid artery. Five and 10 mg of 200- or 300-mum-diameter microspheres were injected into the ICA to evaluate the capture efficiency of the devices. The normalized pressure gradient, flow rate, and vascular resistance in the ICA were calculated from measured values of pressure and flow rate.

RESULTS

The Spider RX captured the most particles (99.9% for 5 mg, 98.4% for 10 mg) and was associated with the slightest increase in pressure gradient (+8%, +15%) for both masses of microspheres injected. The Spider RX and FilterWire EZ were associated with the slightest decreases in flow rate (Spider RX, -1.9% and -12.1%; FilterWire EZ, -3.5% and -8.2%) and the slightest increases in vascular resistance (Spider RX, +10.1% and +33.0%; FilterWire EZ, +20.5% and +32.7%). The device-specific porosity was calculated, and the Spider RX was found to have the greatest at 50.4%; the Emboshield had the lowest at 2.2%.

CONCLUSIONS

The Spider RX and FilterWire EZ had the best overall performances. Design features such as porosity and pore density are important parameters for improving the effectiveness of EPFs. Vascular resistance in the ICA is a flow-derived variable indicative of device performance and affected by the filter design features.

The Angioguard embolic protection device

Endovascular management of cardiovascular disease is quickly becoming a more popular treatment. The effectiveness in using embolic protection devices (EPDs), such as the Angioguard XP filter, during carotid artery stenting (CAS) is a topic of ongoing controversy and scrutiny. Early clinical results indicate that EPDs can reduce complications associated with CAS. However, the incidence of stroke and postprocedural embolic events are statistically similar when comparing CAS with the gold standard in carotid stenosis repair, carotid endarterectomy (CEA). The focus of this manuscript is the critical evaluation of Angioguard XP with respect to numerous in vitro and ex vivo experiments, and clinical trials that have been conducted by the authors and other researchers to investigate the efficacy of EPDs with the objective of suggesting engineering design considerations for future generations of these devices. Angioguard XP has had mixed performance outcomes in in vitro testing reported in the literature. In our laboratory, this device had undesirable measures of performance in bench-top testing protocols using in vitro flow models. Technical considerations relevant to design of EPDs, such as ideal pore size, effective wall apposition in tortuous geometry and maximization of capture efficiency have not been addressed adequately in the literature. It is likely that in the future both CAS and CEA will coexist as potential forms of treatment in the clinical management of cerebrovascular disease.

Carotid Stenting without Angioplasty and without Protection: The Advantages of a Less Invasive Procedure

SUMMARY

Endovascular stenting is a consolidated alternative to thrombendarterectomy in the treatment of extracranial carotid artery atheromasic stenosis. The most common complication of stenting is a distal embolism causing clinically silent orsymptomatic cerebral ischaemia. To prevent this complication distal embolism protection devices are often used but their effectiveness remains unsettled. In addition, there is some evidence that distal embolism may actually be triggered by the protection systems due to clot formationat their distal surface or in the intimal lesions these systems cause. Another rarer complicationis hyperperfusion syndrome arising during both stenting and thrombendarterectomy but more common in endovascular procedures. To avoid these complications the Neuroradiology Service at Bellaria Hospital (Bologna Local Health Trust) has devised a mini-invasive carotid stenting technique that does not require either distal embolism protection or angioplasty. The technique uses only the radial force exerted by the self-expanding stent to widen the atherosclerotic stenosis slowly and gradually. The goal of treatment has also changed from a prompt restoration of the atheromasic vessel's original calibre to slow transformation of the hemodynamic significance of the stenosis. The technique's success lies mainly in selecting the stenosis to treat using CT angiography to analyse plaque morphology and structure.We used the technique to treat 83 stenotic lesions in 75 patients. The study aims to describe and discussour experience.

In vitro performance assessment of distal protection devices for carotid artery stenting: effect of physiological anatomy on vascular resistance

PURPOSE

To assess in vitro the performance of 5 distal protection devices (DPDs) by evaluating the capture efficiency, pressure gradient, volume flow rate, and vascular resistance in the internal carotid artery (ICA).

METHODS

The time-averaged mean peak velocity in the common carotid artery and a blood-mimicking solution were used to simulate physiologICAl conditions in a silicone carotid phantom representing average human carotid artery geometry with a 70% symmetrICAl ICA stenosis. Five milligrams of dyed 200-microm nominal diameter polymer microspheres (larger than the pore size of the devices, except Spider RX, which was tested with 300-microm-diameter particles) were injected into the ICA. The percentages of particles missed after injection and lost during device retrieval were measured for the 5 devices (Spider RX, FilterWire EZ, RX Accunet, Angioguard XP, and Emboshield). The normalized pressure gradient, fraction of the volume flow rate, and vascular resistance in the ICA were calculated.

RESULTS

Spider RX captured the most particles (missing 0.06%, p<0.05) and yielded the smallest normalized pressure gradient increase (4.2%), the largest volume flow rate fraction (0.40), and the smallest vascular resistance in the ICA (272 mmHg/L x min(-1), a 5.4% increase with respect to initial conditions). Angioguard XP captured the fewest particles (missing 36.3%, p<0.05 except Emboshield) and resulted in the largest normalized pressure gradient increase (37%) in the ICA. RX Accunet produced the smallest volume flow rate fraction in the ICA (0.30) and the largest vascular resistance in the ICA (470 mmHg/ L x min(-1), an 82.2% increase). Emboshield migrated approximately 6 cm distal to the original position after particle injection. FilterWire EZ lost the fewest particles during retrieval (0.45%, p<0.05 except Accunet RX and Spider RX) and had the best overall performance with 200-microm emboli (p<0.05 except Accunet RX).

CONCLUSION

None of the devices tested completely prevented embolization. Overall, Spider RX had the best performance and is conjectured to have the best wall apposition of the devices tested. Vascular resistance should be considered a key filter design parameter for performance testing since it represents a quantitative estimation of the "slow-flow phenomenon." Our findings should be extrapolated cautiously to help interventionists choose the best device.

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.

Dual cerebral protection technique during carotid stenting

PURPOSE

To present a technique for internal carotid artery stenting (CAS) with dual cerebral protection in patients with high-grade stenosis caused by large, soft atherosclerotic plaques.

TECHNIQUE

The MO.MA proximal cerebral protection device is first placed in the external and common carotid arteries. Complete blockade of blood flow is achieved by inflating the occlusion balloons. A Spider filter is delivered to the distal internal carotid artery. All procedural steps of CAS are performed during continuous and simultaneous proximal occlusion and distal filter protection. After postdilation of the stent, the occlusion balloons are deflated, and antegrade flow is re-established with the distal filter basket still open.

CONCLUSION

In selected patients with large atherosclerotic plaques, a dual cerebral protection technique during CAS may be a more efficacious form of cerebral protection than a single protection device.

Transcervical carotid stenting with flow reversal for neuroprotection: technique, results, advantages, and limitations

Carotid angioplasty and stenting are progressively earning a role as a less invasive alternative in the treatment of carotid occlusive disease. The most common approach for carotid artery stenting involves transfemoral access and use of a filter or balloon device for neuroprotection. This approach has limitations related to both the site of access and the method of neuroprotection. Specifically, an aortoiliac segment with advanced occlusive or aneurysmal disease or an anatomically unfavorable or atheromatous arch and arch branches can significantly limit the safety of the retrograde transfemoral pathway to the carotid bifurcation. Additionally, data provided by the use of transcranial Doppler monitoring and diffusion-weighted magnetic resonance imaging in patients undergoing filter- or balloon-protected carotid artery stenting demonstrate that currently available devices are associated with a considerable incidence of cerebral embolization. To address these limitations, we, along with others, have employed a direct transcervical approach for carotid artery stenting that incorporates the principle of flow reversal for neuroprotection. The technique bypasses all of the anatomic limitations of transfemoral access and simplifies the application of flow reversal, which is one of the safest neuroprotection techniques. The purpose of this review is to describe our method of transcervical carotid artery stenting, review the accumulating outcomes data, and discuss the clinical advantages of and indications for this increasingly popular technique.

Embolic protection devices for carotid artery stenting: is there a difference between filter and distal occlusive devices?

OBJECTIVES

We sought to compare the efficacy of a filter embolic protection device (F-EPD) and a distal occlusive embolic protection device (DO-EPD) in patients undergoing carotid artery stenting (CAS).

BACKGROUND

The embolic protection device (EPD) may lower the periprocedural rate of cerebral ischemic events during CAS. However, it is unclear whether there is a difference in effectiveness between the different types of EPD.

METHODS

We analyzed data from the Carotid Artery Stent (CAS) Registry.

RESULTS

From July 1996 to July 2003, 1,734 patients were included in the prospective CAS Registry. Of these patients, 729 patients were treated with an EPD, 553 (75.9%) with F-EPD, and 176 (24.1%) with DO-EPD. Patients treated with DO-EPD were more likely to be treated for symptomatic stenosis (64.5% vs. 53.4%, p = 0.011). The carotid lesions in patients treated under DO-EPD seemed to be more complicated, as expressed by a higher proportion of ulcers (p = 0.035), severe calcification (p = 0.039), a longer lesion length (p = 0.025), and a higher pre-interventional grade of stenosis (p < 0.001). The median duration of the CAS intervention was 30 min in the DO-EPD group, compared with 48 min in the filter group (p < 0.001). No differences in clinical events rate between the two groups of protection devices were observed. Multivariate analysis on the occurrence of the combined end point of in-hospital death or stroke found no difference between filter- and DO-EPD (4 of 176 [2.3%] for DO-EPD vs. 10 of 551 [1.8%] for F-EPD; adjusted odds ratio = 1.04, 95% confidence interval 0.24 to 4.44; p = 0.958).

CONCLUSIONS

Filter EPD is the currently preferred method of EPD in clinical practice. Both F-EPD and DO-EPD seem to be equally effective during CAS.

The capture of visible debris by distal cerebral protection filters during carotid artery stenting: Is it predictable?

OBJECTIVES

Neurologic complications during carotid artery stenting (CAS) are most clearly associated with embolization of visible debris. Distal filter devices may provide cerebral protection by capturing clinically significant debris. However, they increase procedural time and expense and have their own set of complications. The current study was undertaken to identify the clinical factors predictive for the presence or absence of visible debris captured by distal filter devices during CAS.

METHODS

Patients undergoing CAS with use of a distal filter device (n = 279) were prospectively entered into an investigational carotid registry. Recorded variables were classified as patient-, lesion-, or procedure-related. The filter was assessed for visible debris in each case. The odds ratio (OR) and 95% confidence interval (CI) were determined for each variable to predict visible debris. The ability of each variable to predict the absence of visible debris was assessed by calculating the individual negative predictive value (NPV).

RESULTS

Visible debris was present in 169 filters (60.3%). There was an increased risk of visible debris found with several variables (OR, 95% CI): hypertension (2.9, 1.7 to 5.2), hypercholesterolemia (2.3, 1.4 to 3.9), stent diameter >9 mm (16.6, 9.0 to 30.0), and any neurologic event (4.2, 1.5 to 9.9). The NPV failed to exceed 0.80 (80%) for any variable. The NPV of the variables with a significantly elevated OR was as follows: hypertension (0.60), hypercholesterolemia (0.52), stent diameter >9 mm (0.75), and any neurologic event (0.38).

CONCLUSIONS

Several clinical variables are associated with the presence of visible debris captured by distal filter devices. The current study failed to identify any variables capable of consistently predicting the absence of visible debris. These findings support the routine rather than the selective use of cerebral protection during CAS.

Transcervical carotid stenting with internal carotid artery flow reversal: Feasibility and preliminary results

OBJECTIVE

Transfemoral carotid artery stenting (CAS), with or without distal protection, is associated with risk for cerebral and peripheral embolism and access site complications. To establish cerebral protection before crossing the carotid lesion and to avert transfemoral access complications, the present study was undertaken to evaluate a transcervical approach for CAS with carotid flow reversal for cerebral protection.

METHODS

Fifty patients underwent CAS through a transcervical approach. All patients with symptoms had greater than 60% internal carotid artery (ICA) stenosis, and all patients without symptoms had greater than 80% ICA stenosis. Twenty-one patients (42%) had symptomatic disease or ipsilateral stroke, and 8 patients (16%) had contralateral stroke. Four patients (8%) had recurrent stenosis, 7 patients (14%) had contralateral ICA occlusion, and 1 patient (2%) had undergone previous neck radiation. Twenty-seven procedures (54%) were performed with local anesthesia, and 23 (46%) with general anesthesia. Using a cervical cutdown, flow was reversed in the ICA by occluding the common carotid artery and establishing a carotid-jugular vein fistula. Pre-dilation was selective, and 8-mm to 10-mm self-expanding stents were deployed and post-dilated with 5-mm to 6-mm balloons in all cases.

RESULTS

The procedure was technically successful in all patients, without significant residual stenoses. No strokes or deaths occurred. There was 1 wound complication (2%). All patients were discharged within 2 days of surgery. Mean flow reversal time was 21.4 minutes (range, 9-50 minutes). Carotid flow reversal was not tolerated in 2 patients (4%). Early in the experience, carotid flow reversal was not possible in 1 patient, and there were 1 major and 3 minor common carotid artery dissections, which resolved after stent placement. One intraoperative transient ischemic attack (2%) occurred in 1 patient in whom carotid flow was not reversed, and 1 patient with a contralateral ICA occlusion had a contralateral transient ischemic attack. At 1 to 12 months of follow-up, all patients remained asymptomatic, and all but 1 stent remained patent.

CONCLUSION

Transcervical CAS with carotid flow reversal is feasible and safe. It can be done with the patient under local anesthesia, averts the complications of the transfemoral approach, and eliminates the increased complexity and cost of cerebral protection devices. Transcervical CAS is feasible when the transfemoral route is impossible or contraindicated, and may be the procedure of choice in a subset of patients in whom carotid stenting is indicated.

Carotid angioplasty with internal carotid artery flow reversal is well tolerated in the awake patient

OBJECTIVE

The purpose of this study was to evaluate the neurologic tolerance and changes in ipsilateral hemispheric oxygen saturation during transcervical carotid artery stenting with internal carotid artery (ICA) flow reversal for embolic protection.

PATIENTS AND METHODS

This was a prospective study of 10 patients (mean age 68 years) undergoing transcervical carotid angioplasty and stenting. All ICA stenoses were greater that 70%. Seven patients had an ipsilateral hemispheric stroke (3) or transient ischemic attack (4), two patients had a contralateral stroke, and one patient was asymptomatic. Nine procedures were done under local anesthesia. Cerebral protection was established through a cervical common carotid (CCA) cutdown to create an external fistula between the ICA and the internal jugular vein with temporally CCA occlusion. Venous oxygen saturation (SVO(2)) was continuously monitored through a catheter placed in the distal internal jugular vein. Mental status and motor-sensory changes were categorized and assessed throughout and after the procedure.

RESULTS

All procedures were technically successful without significant residual stenosis. Mean ICA flow reversal time was 22 minutes (range, 15 to 32). Common carotid artery (CCA) occlusion produced a slight (SVO(2) = 72.6%+/-9.4) but significant decrease (P =.012) in SVO(2), compared with baseline (SVO(2) = 77% +/-10.5). During ICA flow reversal (SVO(2) = 72.4% +/-10.1) cerebral oxygen saturation did not change compared with CCA occlusion alone (P =.85). Transient balloon occlusion during angioplasty of the ICA (SVO(2) = 64.6%+/-12.9) produced a significant decrease in cerebral SVO(2) compared with CCA occlusion (P =.015) and compared with CCA occlusion with ICA flow reversal (P =.018). No mental status changes or ipsilateral hemispheric focal symptoms occurred during CCA occlusion with ICA flow reversal. One patient with contralateral ICA occlusion sustained brief upper extremity weakness related to the contralateral hemisphere. Five patients sustained a vasovagal response during balloon dilatation, four did not require treatment, and one had asystole requiring atropine injection. Mean SVO(2) saturation was not different in these five patients compared with the five who did not sustain a vasovagal response. No deaths or neurologic deficits occurred within 30 days after the procedure.

CONCLUSIONS

Our data suggest that transcervical carotid angioplasty and stenting with ICA flow reversal is well tolerated in the awake patient, even in the presence of symptomatic carotid artery disease. Cerebral oxygenation during ICA flow reversal is comparable to that during CCA occlusion. ICA angioplasty balloon inflation produces a decrease in cerebral SVO(2) significantly greater than that occurring during ICA flow reversal.

Filter devices for cerebral protection during carotid angioplasty and stenting

The risk of embolization during carotid artery stenting (CAS) has been the foremost reason for the cautious acceptance of this percutaneous alternative to carotid endarterectomy. To address this issue, numerous embolic protection devices are being evaluated as an adjunct to CAS for neuroprotection. Among the 3 main categories of these devices, distal filters, which trap embolic debris while maintaining distal cerebral perfusion, have attracted the most corporate interest. This review focuses on the emerging field of embolic protection filters for use in CAS.

Comparison of 4 Cerebral Protection Filters for Carotid Angioplasty:An In Vitro Experiment Focusing on Carotid Anatomy

PURPOSE

To assess the influence of internal carotid artery (ICA) tortuosity on the effectiveness of 4 cerebral protection filters in an in vitro bench-top model.

METHODS

To simulate the anatomical arterial variants, 3 open flow models were constructed: one with normal carotid anatomy, 1 representing a mildly tortuous ICA, and a third imitating a severely tortuous ICA. Polyvinyl alcohol particles (150-1000 microm) served as the embolic material; the emboli were divided into 3 groups according to size: small (150-250 microm), medium (355-500 microm), and large (710-1000 microm). Five milligrams of each size group were injected separately into the ICA proximal to each of 4 protection filters: AngioGuard, FilterWire EX, TRAP, and NeuroShield. Emboli that were not caught by the protection system or were washed into the external carotid artery (ECA) ran into an effluent filter and were weighed and classified according to size.

RESULTS

In 240 test runs, the FilterWire EX presented the lowest weight of emboli in the ICA effluent under all anatomical conditions: normal anatomy 0.39 mg (2.58%), mild tortuosity 0.45 mg (2.99%), and severe tortuosity 0.50 mg (3.33%) (p>0.05). The Angioguard system showed the worst results: normal 1.21 mg (98.03%), mild tortuosity 2.54 mg (16.84%), and severe tortuosity 3.14 mg (20.91%) (p<0.001) compared to the FilterWire EX and the NeuroShield systems. The only protection device displaying no significant differences in all of the 3 emboli sizes was the FilterWire EX (p>0.05). Relevant differences in effectiveness in mildly and severely tortuous ICAs were apparent among the other devices. For all emboli sizes, the differences of the AngioGuard and TRAP systems were highly significant (p<0.001). There was no significant difference between the FilterWire EX and the NeuroShield.

CONCLUSIONS

The only protection device showing no significant decrease in efficacy in the tortuous ICA models was the FilterWire EX. In both tested anatomical variants, the protection systems ranked in the same order of effectiveness. None of the tested devices prevented embolization completely.