Stent placement versus percutaneous transluminal angioplasty of human carotid arteries in cadavers in situ: distal embolization and findings at intravascular US, MR imaging and histopathologic analysis

What should be the Optimal Carotid Stent Opening Rate Without Post-Dilation?

BACKGROUND

There is not a widely accepted optimal rate of stent opening in patients underwent carotid artery stenting. In this study we evaluated the effect of carotid stent opening rate (CSOR) without performing post-dilation on in-hospital and long-term outcomes.

METHODS

A total of 825 patient patients underwent carotid artery stenting without post-dilation enrolled to the study. The patients divided into two groups according to their final CSOR (50% ≤ Post-stent deployment (SD) <80% and 80% ≤ Post-SD ≤ 100%). In-hospital and 3-year outcomes were compared between the groups.

RESULTS

During hospitalization, the rate of ipsilateral stroke, major stroke and transient ischemic attacks were similar between the groups (respectively; 6.2% vs. 4.1, P = 0.190; 1.5% vs. 1.8, P = 0.811; 1.5% vs. 1.9%, P = 0.683). The 3-year Kaplan-Meier overall survival rates for the first and second groups were 87.6% and 84.4%, respectively (log rank test P = 0.426). The 3-year Kaplan-Meier overall cumulative ipsilateral stroke rates for the first and second groups were 88.0% and 88.6%, respectively (log rank test P = 0.409) CONCLUSION: Our study demonstrated that a CSOR higher than 50% without performing a post-dilation might be an effective therapeutic approach since there was not a significant difference regarding outcomes between the patients with a 50% ≤ Post-SD <80% and 80% ≤ Post-SD ≤ 100%. The need for post-stent balloon dilation might have been eliminated due to subsequent stent self-expansion.

Impact of plaque dilation before carotid artery stent deployment

OBJECTIVE

Plaque stability is of utmost importance for stroke prevention in the perioperative period (within 24 hours) following carotid artery stenting (CAS). Although carotid plaque is entrapped between stent struts after stent deployment, postdilation can cause a scissoring effect on the plaque, increasing the risk of postprocedural embolic events due to plaque prolapse. Maximum carotid plaque dilation before stent deployment may reduce this risk. This study analyzed the effect of maximum dilation of the carotid plaque before stent deployment (max-pre-SD) or after stent deployment (post-SD) on macroscopic plaque debris, hemodynamic depression (HD), and immediate major adverse events.

METHODS

This prospective nonrandomized multicenter study analyzed patients treated for carotid artery stenosis with CAS from January 2014 to August 2016. Clinical and morphologic characteristics and operative details were analyzed with logistic regression analysis for macroscopic debris and HD. The number of microembolic signals (MESs) was assessed by transcranial Doppler and analyzed.

RESULTS

A total of 309 patients were enrolled and treated with standard CAS performed using a proximal occlusion cerebral embolic protection device; 149 received max-pre-SD and 160 were treated with post-SD. Technical success was achieved in 100% of cases. Macroscopic debris and HD were significantly different between the two groups in favor of max-pre-SD (P < .001). A significant difference in intraprocedural MESs between the groups was detected. Compared with post-SD, max-pre-SD significantly reduced mean MES counts (8.1% vs 68.1%; P < .001). Patients treated with post-SD had a significantly increased risk of MESs in the immediate postoperative period compared with patients treated with max-pre-SD (41.9% vs 1.3%; P < .001).This result was mainly due to the small number of events encountered. Patients treated with post-SD had a 12-fold increased risk of macroscopic debris collection (odds ratio [OR], 12.36; 95% confidence interval [CI], 5.68-26.87; P < .001) and an 18 times increase in HD risk (OR, 17.80; 95% CI, 5.27-60.17; P < .001) compared with patients treated with max-pre-SD. The heterogeneous, mainly echolucent plaque type significantly highly increased the risk of macroscopic debris (OR, 78.45; 95% CI, 8.70-707.09; P < .001) while acting as a protective factor against HD (OR, 0.02; 95% CI, 0.006-0.11; P < .001) along with echogenic or echolucent complex plaques with irregular surface plaque types (OR, 0.10; 95% CI, 0.031-0.336; P < .001). No significant differences between groups (max-pre-SD group and post-SD) were detected in immediate major adverse events (minor stroke, 2.0% and 2.5% [P = .461]; major stroke, 0% and 0.6% [P = .334], respectively).

CONCLUSIONS

Max-pre-SD seems to be a safe and feasible technical modification to the CAS procedure. Macroscopic debris, HD, and MESs are significantly reduced compared with CAS with post-SD. Further research with larger, randomized cohorts of patients is required to establish the superiority of this technical modification.

The usefulness of Duplex Doppler ultrasound in the angiological and dermatological diagnosis of patients with blue toe syndrome

Introduction

Peripheral microembolism is one of the most frequent causes of acute limb ischemia. In order to effectively prevent relapses it is essential to localize and eliminate the source of embolism.

Aim

To evaluate the role of Duplex Doppler ultrasound examination in identifying the causes of blue toe syndrome (BTS).

Material and methods

The group of 165 patients with clinical symptoms of BTS on their upper limbs (n = 16) and lower limbs (n = 149) was investigated. They all underwent Duplex Doppler ultrasound of the major arteries of the extremities, where ischemic changes occurred.

Results

Morphological and functional changes which might be potential sources of microembolism were identified in 146 patients. These changes included significant short-length stenoses or unstable atherosclerotic plaque (n = 73), true aneurysms (n = 42) and pseudoaneurysms (n = 17). In 11 cases, pathology of vascular prostheses in the form of anastomotic aneurysms, infection and residual thrombi after fibrinolysis was detected. In all cases, Duplex diagnosis was confirmed by other imaging and intraoperative tests.

Conclusions

Duplex Doppler ultrasound of the arteries in the affected limb with a full length view should be the first-line examination in diagnosing patients with BTS. In the absence of hemodynamic blood flow disturbances in the major arteries in patients with symptoms of BTS, it is advisable to start haematological tests to identify/exclude congenital or acquired thrombophilia.

Selective-versus-Standard Poststent Dilation for Carotid Artery Disease: A Systematic Review and Meta-Analysis

BACKROUND

The safety and efficacy of standard poststent angioplasty in patients undergoing carotid artery stent placement have not been well-established.

PURPOSE

We conducted a systematic review of the literature to evaluate the safety and efficacy of carotid artery stent placement and analyzed outcomes of standard-versus-selective poststent angioplasty.

DATA SOURCES

A systematic search of MEDLINE, EMBASE, Scopus, and the Web of Science was performed for studies published between January 2000 and January 2015.

STUDY SELECTION

We included studies with >30 patients describing standard or selective poststent angioplasty during carotid artery stent placement.

DATA ANALYSIS

A random-effects meta-analysis was used to pool the following outcomes: periprocedural stroke/TIA, procedure-related neurologic/cardiovascular morbidity/mortality, bradycardia/hypotension, long-term stroke at last follow-up, long-term primary patency, and technical success.

DATA SYNTHESIS

We included 87 studies with 19,684 patients with 20,378 carotid artery stenoses. There was no difference in clinical (P = .49) or angiographic outcomes (P = .93) in carotid artery stent placement treatment with selective or standard poststent balloon angioplasty. Both selective and standard poststent angioplasty groups had a very high technical success of >98% and a low procedure-related mortality of 0.9%. There were no significant differences between both groups in the incidence of restenosis (P = .93) or procedure-related complications (P = .37).

LIMITATIONS

No comparison to a patient group without poststent dilation could be performed.

CONCLUSIONS

Our meta-analysis demonstrated no significant difference in angiographic and clinical outcomes among series that performed standard poststent angioplasty and those that performed poststent angioplasty in only select patients.

Plaque morphology (the PLAC Scale) on CT angiography: predicting long-term anatomical success of primary carotid stenting

OBJECT

Carotid angioplasty and stenting has emerged as an alternative to carotid endarterectomy for the treatment of atherosclerotic carotid stenosis. Primary carotid stenting, performed using self-expanding stents alone without deliberate use of embolic protection devices and balloon angioplasty, has been shown to be effective and faster, cheaper, and potentially safer than conventional techniques. However, the long-term morphological results of this technique have not been established. The aim of this study was to determine whether preprocedural carotid plaque imaging at the site of maximal stenosis by using CT angiography (CTA) could predict the long-term morphological outcome of primary carotid stenting.

METHODS

One hundred eighty-one patients were treated over an 11-year period. Preprocedural CTA was performed in 102 of these. A morphological scale (the Predicting Long-term outcome with Angioplasty of the Carotid artery [PLAC] Scale), with grades from 0 to 4 and A or B, was used to evaluate the circumferential degree of plaque calcification, and the presence or absence of soft plaque. All patients were followed using duplex carotid ultrasound and plain radiographs. Satisfactory morphological outcome was defined as a peak systolic velocity < 120 cm/s and internal carotid artery/common carotid artery ratio < 1.4.

RESULTS

The average follow-up duration was 29.7 months (median 24.5 months, range 0.3–87 months). Univariate logistic regression demonstrated that a low calcification grade (p < 0.001), less thick calcification (p < 0.001), and moderate amounts of soft plaque (p < 0.001) are factors that are highly associated with good long-term outcome. Multivariate analyses confirmed that these factors are independent of each other in predicting outcome.

CONCLUSIONS

The long-term morphological outcome of primary carotid stenting was predicted with considerable accuracy by using a straightforward CTA carotid plaque grading scale.

Delayed progressive bilateral supraclinoid internal carotid artery stenosis in a patient with a ruptured basilar artery aneurysm

Cerebral vasospasm is a common radiographic and clinical diagnosis after subarachnoid hemorrhage. Conventional treatments include medical hypertension, hypervolemia, and modest hemodilution. When medical treatments fail in severe vasospasm cases, intra-arterial vasodilation and balloon angioplasty may be useful. We present a 47-year-old woman with a ruptured basilar artery aneurysm who developed severe bilateral internal carotid artery vasospasm requiring bilateral balloon angioplasty. Prior to discharge, the patient's bilateral stenosis had improved. Three months post-discharge, severe restenosis in her bilateral internal carotid arteries occurred; a rare event. Balloon angioplasty has been demonstrated to histologically tear and stretch collagen fibers in the vessel wall and overexpansion of vessels may lead to a neo-intimal reaction that is similar to the one seen after stent placement in the intracranial circulation. Clinicians should be aware of the possibility of delayed and progressive stenosis in vessels treated with angioplasty. Follow-up vascular imaging is necessary after subarachnoid hemorrhage. Future study is required on the treatment paradigms necessary for this delayed restenosis.

Reversibility of ischemic findings on 3-tesla magnetic resonance T2(*)-weighted image after recanalization

Ischemic vessel signs (IVS) can be detected on 3-tesla T2(*)-weighted magnetic resonance images as a vessel enlargement at the territory of acute ischemia caused by major vessel occlusion or stenosis. Here, we studied changes in IVS before and after recanalization by the administration of intravenous recombinant tissue plasminogen activator (IV rtPA), carotid artery stenting or percutaneous transluminal angioplasty in patients with major vessel occlusion or stenosis. We performed magnetic resonance imaging for all patients treated by IV rtPA at the time of admission, shortly after and 24-72 hours after treatment with IV rtPA. We reviewed the IVS to assess its natural course of IVS by assessing patients who did not recanalize. IVS tended to disappear after recanalization. Conversely, in patients without recanalization, IVS did not disappear shortly after IV rtPA; rather, it disappeared 24-72 hours after IV rtPA, especially in the presence of complete infarction. Recanalization by IV rtPA or endovascular treatment contributed to improved clinical deficits or the prevention from further progression. IVS can be a parameter of misery perfusion and an important factor to detect the patients who have an indication of treatment for recanalization.

Carotid artery stenting without post-stenting balloon dilatation

PURPOSE

To evaluate the clinical outcome and MRI findings after carotid artery stenting (CAS) without post-dilatation.

METHODS

Between May 2005 and April 2012, a total of 169 consecutive patients (61.4% symptomatic) underwent 176 CAS procedures performed with an embolic protection device (GuardWire, n=116; FilterWire EZ, n=60). All stents were deployed without post-dilatation. Periprocedural complications and mid-term outcomes were analyzed.

RESULTS

The stroke rate was 2.3% within 30 days post-CAS (asymptomatic patients 1.5%; symptomatic patients 2.8%). Cerebral infarction occurred in one asymptomatic patient (1.5%) and one symptomatic patient (0.9%). Intracranial hemorrhage occurred in two symptomatic patients (1.9%). Post-CAS diffusion-weighted imaging (DWI) revealed a high-intensity area in 26 of 176 procedures (14.8%). Ipsilateral stroke after 31 days occurred in two patients (1.1%) and restenosis occurred in six (3.4%). A post-CAS comparison of the embolic protection devices revealed no difference in stroke incidence within 30 days and in DWI high-intensity area.

CONCLUSIONS

Our CAS procedure without post-dilatation is feasible, safe and associated with a low incidence of stroke and restenosis.

[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 stenting without angioplasty and cerebral protection: a single-center experience with up to 7 years' follow-up

BACKGROUND AND PURPOSE

The use of cerebral protection during CAS in the treatment of carotid artery disease is matter of controversy. The purpose of this study was to evaluate the outcome of CASWBAP in a large cohort of patients, with ≤7 years' follow-up.

MATERIALS AND METHODS

Two hundred thirty-six patients with 255 symptomatic carotid stenoses and/or with high-risk-morphology plaques of >50% and asymptomatic plaques of >70% were prospectively identified. Patients underwent neurologic and carotid US examination before the procedure and during follow-up at 1, 3, 6, and 12 months and annually thereafter. Plain films of the neck were obtained immediately after the procedure and then at 1 and 3 months.

RESULTS

Technical success was achieved in 253/255 (99%) patients. Primary stent placement was successful in 248/253 (98%) patients. Neurologic periprocedural complications within 30 days included 1 (0.4%) nondisabling stroke, 1 (0.4%) disabling stroke, 11 (4.3%) TIAs, and 1 (0.4%) death. The mean duration of follow-up was 23 ± 1.4 months (range, 3-84 months). During the follow-up period, there were 9 additional deaths (7 unrelated to the carotid disease and 2 stroke-related) and 2 strokes (in other vascular territories). The degree of stenosis decreased from a mean of 82% before the procedure to a mean of 30% immediately after. During follow-up, 38 (14.8%) angioplasties were performed due to restenosis in 19 (7.4%) patients, lack of stent expansion in 14 (5.4%), or both in 5 (1.9%).

CONCLUSIONS

CASWBAP is effective and safe with a low incidence of periprocedural complications, providing satisfactory long-term clinical results.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

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.

Results using a self-expanding stent alone in the treatment of severe symptomatic carotid bifurcation stenosis

Object

Conventional endovascular therapy for carotid stenosis involves placement of an embolic protection device followed by stent insertion and angioplasty. A simpler approach may be placement of a stent alone. The authors determined how often this approach could be used to treat patients with carotid stenosis, and assessed which factors would preclude this approach.

Methods

Over a period of 6 years, 97 patients with symptomatic carotid stenosis were treated with the intention of using a “stent-only” approach. Arteries in 77 patients (79%) were treated with stents alone, 13 required preinsertion balloon dilation, 6 postinsertion dilation, and 1 both pre- and postinsertion dilation.

Results

The mean stenosis according to North American Symptomatic Carotid Endarterectomy Trial criteria was reduced from 82 to 40% in the stent-only group and from 89 to 37% in the stent and balloon angioplasty group. The 30-day stroke and death rate was 7.2%. Patients were followed for a mean of 15 months. In the stent-alone group, the mean preoperative Doppler peak systolic velocity (PSV) was 409 cm/second, with an internal carotid artery/common carotid artery (ICA/CCA) ratio of 7.2. At follow-up review, the PSV decreased to 153 cm/second and the ICA/CCA ratio to 2.1. In the angioplasty group the mean preoperative PSV was 496 cm/second and the ICA/CCA ratio was 9.2, decreasing to 163 cm/second and 2, respectfully, at follow-up evaluation. Restenosis occurred in 12.8% of patients at 6 months and in 15.9% at 1 year. One stroke occurred during the follow-up period in each group. Using multivariable analysis, factors precluding the “stent-only” approach were as follows: severity of stenosis, circumferential calcification, and no history of hyperlipidemia.

Conclusions

Balloons may not be required to treat all patients with carotid stenosis. A stent alone was feasible in 79% of patients, and 79% of patients were alive and free from ipsilateral stroke or restenosis at 1 year. Restenosis rates with this approach are higher than with conventional angioplasty and stent insertion. Carotid arteries with very severe stenoses (> 90%) and circumferential calcification may be more successfully treated with angioplasty combined with stent placement.

Protected carotid stenting in high-surgical-risk patients: The ARCHeR results

BACKGROUND

Carotid endarterectomy is the standard of care for most patients with severe extracranial carotid bifurcation disease. However, its safety and efficacy in patients with significant surgical risk are unclear. The ARCHeR (ACCULINK for Revascularization of Carotids in High-Risk patients) trial was performed to determine whether carotid artery stenting with embolic protection is a safe and effective alternative to endarterectomy in high-surgical-risk patients.

METHODS

The ARCHeR trial is a series of three sequential, multicenter, nonrandomized, prospective studies. Forty-eight sites enrolled 581 high-surgical-risk patients between May 2000 and September 2003. Patients with severe carotid artery stenosis (angiographically defined, symptomatic > or =50%, or asymptomatic > or =80%) had an ACCULINK nitinol stent implanted. The ACCUNET filter embolic protection system was added to the procedure in the final 2 studies (422 patients). The primary efficacy end point was a composite of periprocedural (< or =30 days) death, stroke, and myocardial infarction, plus ipsilateral stroke between days 31 and 365.

RESULTS

The 30-day rate of death/stroke/myocardial infarction was 8.3% (95% confidence interval [CI], 6.2%-10.8%), and that of stroke/death was 6.9% (95% CI, 5.0%-9.3%). Most (23/32) strokes were minor, of which more than half (12/23) returned to baseline National Institutes of Health Stroke Scale scores within 30 days. The 30-day major/fatal stroke rate was 1.5% (95% CI, 0.7%-2.9%). No hemorrhagic strokes were observed in the study. Ipsilateral cerebrovascular accident occurred in 1.3% between 30 days and 1 year, thus giving a primary composite end point of 30-day death/stroke/myocardial infarction plus ipsilateral stroke at 1 year of 9.6% (95% CI, 7.2%-12.0%), which is below the 14.4% historical control comparator. Target lesion revascularization at 12 months and 2 years was 2.2% and 2.9%, respectively.

CONCLUSIONS

The ARCHeR results demonstrate that extracranial carotid artery stenting with embolic filter protection is not inferior to historical results of endarterectomy and suggest that carotid artery stenting is a safe, durable, and effective alternative in high-surgical-risk patients.

Complications and Follow-up after Unprotected Carotid Artery Stenting

PURPOSE

This prospective study was undertaken to determine the success rate, complications, and outcome of carotid artery stenting (CAS) without the use of cerebral protection devices.

METHODS

During 12 months, 94 high-grade stenoses of the carotid artery in 91 consecutive patients were treated. Sixty-six (70%) of the stenoses were symptomatic and 28 (30%) were asymptomatic.

RESULTS

In all 94 carotid stenoses CAS was successfully performed. During the procedure and within the 30 days afterwards, there were 2 deaths and 3 major strokes in the 66 symptomatic patients, resulting in a combined death and stroke rate of 5 of 66 (7%). Only one of these complications, a major stroke, occurred during the procedure. In the 6-month follow-up, one additional major stroke occurred in a originally symptomatic patient resulting in a combined death and stroke rate of 6 of 66 (10%) for symptomatic patients at 6 months. No major complications occurred in asymptomatic patients during the procedure or in the 6-month follow-up period. At 6 months angiographic follow-up the restenosis rate with a degree of >50% was 3 of 49 (6%) and the rate with a degree of >or=70% was 1 of 49 (2%).

CONCLUSIONS

Cerebral embolization during CAS is not the only cause of the stroke and death rate associated with the procedure. The use of cerebral protection devices during the procedure may therefore not prevent all major complications following CAS.

Stent-Protected Carotid Angioplasty Using a Membrane Stent: A Comparative Cadaver Study

PURPOSE

To evaluate the performance of a prototype membrane stent, MembraX, in the prevention of acute and late embolization and to quantify particle embolization during carotid stent placement in human carotid explants in a proof of concept study.

METHODS

Thirty human carotid cadaveric explants (mild stenoses 0-29%, n = 23; moderate stenoses 30-69%, n = 3; severe stenoses 70-99%, n = 2) that included the common, internal and external carotid arteries were integrated into a pulsatile-flow model. Three groups were formed according to the age of the donors (mean 58.8 years; sample SD 15.99 years) and randomized to three test groups: (I) MembraX, n = 9; (II) Xpert bare stent, n = 10; (III) Xpert bare stent with Emboshield protection device, n = 9. Emboli liberated during stent deployment (step A), post-dilatation (step B), and late embolization (step C) were measured in 100 microm effluent filters. When the Emboshield was used, embolus penetration was measured during placement (step D) and retrieval (step E). Late embolization was simulated by compressing the area of the stented vessel five times.

RESULTS

Absolute numbers of particles (median; >100 microm) caught in the effluent filter were: (I) MembraX: A = 7, B = 9, C = 3; (II) bare stent: A = 6.5, B = 6, C = 4.5; (III) bare stent and Emboshield: A = 7, B = 7, C.=.5, D = 8, E = 10. The data showed no statistical differences according to whether embolic load was analyzed by weight or mean particle size. When summing all procedural steps, the Emboshield caused the greatest load by weight (p = 0.011) and the largest number (p = 0.054) of particles.

CONCLUSIONS

On the basis of these limited data neither a membrane stent nor a protection device showed significant advantages during ex vivo carotid angioplasty. However, the membrane stent seems to have the potential for reducing the emboli responsible for supposed late embolization, whereas more emboli were observed when using a protection device. Further studies are necessary and warranted.

In Vitro Comparison of Self-Expanding Versus Balloon-Expandable Stents in a Human Ex Vivo Model

The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 +/- 1.0 mm) and mean volumes (0.60 +/- 0.14 ml/cm) than in the balloon-expandable stent group (10.1 +/- 0.3 mm and 0.71 +/- 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23-0.78 ml/cm) than in balloon-expandable stents (range: 0.66-0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents.

Error estimation of geometrical data obtained by histomorphometry of oblique vessel sections: a computer model study

The errors of radius and wall thickness of a single vessel due to oblique sectioning in histomorphometry are expressed as a function of the circular shape factor (CSF) of the section's lumen, assuming cylindrical geometry and the absence of tissue deformation. Using computer model trees generated by constrained constructive optimization, mean errors are estimated for an ensemble of vessel segments. A geometrical exclusion criterion for segments cut too obliquely is defined on the basis of a CSF-cutoff value. It is shown that CSF-values ranging from 0.95 to 0.9 are reasonable choices for a cutoff and lead to mean errors of the same order of magnitude (9.6% [9.3%] to 15.4% [14.8%] for the radius [wall thickness]) as errors due to histological tissue processing.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A review of technical advances in interventional magnetic resonance imaging

Initial research in the development of interventional magnetic resonance (MR) imaging in the late 1980s and early to mid-1990s focused on pulse sequences, devices, and clinical applications. This focus was largely a result of the limited number of areas in which the academic research community leading the development could provide innovation on the MR systems of the time. However, during the past decade, computational power, higher bandwidth graphical displays, faster computer networks, improved pulse sequence architectures, and improved technical specifications have accelerated the pace of development on modern MR systems. Today, it is the combination of multiple system factors that are enabling the future of interventional MR. These developments, their impact on the field, and newly emerging applications are described.

Characteristics of Peripheral Microembolization During Iliac Stenting: Doppler Ultrasound Monitoring

OBJECTIVE

To evaluate the characteristics of distal microembolic signals (MES) during iliac stenting using Doppler ultrasound monitoring.

DESIGN

Prospective clinical study.

METHODS

A 2-MHz probe was used to monitor continuously at the ipsilateral tibioperoneal trunks during technically and hemodynamically successful iliac stenting in 10 patients without infrainguinal occlusive lesion. MESs at guide-wire, balloon, or stent crossing (phase 1), predilatation (phase 2), stent deployment (phase 3), postdilatation (phase 4), and contrast medium or heparinized saline injection (at injection) were analyzed. Differentiation of gaseous emboli from particulate emboli was achieved by calculation of the sample volume length.

RESULTS

No distal embolic complications were observed. Five hundred and forty-one MESs were detected. The MES incidence and intensity in phase 3 were significantly higher than those in phase 1, phase 2, and phase 4 (p<0.05). The MES intensity at injection was significantly higher than that in each of four phases (p<0.0001).

CONCLUSIONS

Both the MES incidence and intensity were highest at stent deployment. Further study is required of microembolism during endovascular procedures in the lower extremities.

Observing the carotid debris aspirated during carotid stenting: technical note

OBJECTIVES

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

METHODS

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

RESULTS

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

DISCUSSION

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

Experimental Functional Analysis of Self-Expanding Stents Using a New Developed Ex Vivo Model

OBJECTIVE

To modify an ex vivo test procedure for balloon expandable stents as a means to evaluate the mechanical properties of self-expanding stents.

METHODS

Ten stents each of 7 different stent models measuring 10 mm in diameter (LUMINEXX Vascular Stent/Memotherm-FLEXX Vascular Stent [identical to Bard], Jostent SelfX, Jostent SelfX high radial force [Jomed], sinus-Repo stent, sinus-SuperFlex stent [Optimed], S.M.A.R.T. stent [Cordis], and Easy Wallstent [Boston Scientific]) were implanted in common iliac arteries taken from cadavers (n = 35). They were randomized to either the right or left bifurcation. The vessels were then maintained at 37 degrees C for 24 hours in a special solution that inhibited autolysis, making it possible for the stents to expand. Afterward, they were filled with silicone caoutchouc. After another 24 hours, the vessel walls and stents were removed from the hardened casts. By means of fine analytic measurements, we demonstrated that the volume of a hardened cast formed in the stent cylinder is an indirect but precise measure of the radial force of a stent. Furthermore, using correlation analysis, we examined the relationship between radial force and vessel diameter as well as that between radial force and the degree of arteriosclerosis.

RESULTS

The differences between the actually measured volumes, ie, radial strength, (1 cm stent length) of the various stent models (LUMINEXX/Memotherm-FLEXX: 0.6198 mL +/- 0.1537 mL; Jostent SelfX: 0.6756 mL+/- 0.1298 mL; Jostent SelfX high radial force: 0.6321 mL+/- 0.1817 mL; sinus-Repo stent: 0.5508 mL+/- 0.1485 mL; sinus-SuperFlex stent: 0.6174 mL+/- 0.0953 mL; S.M.A.R.T. stent: 0.5627 mL+/- 0.1270 mL; and Easy Wallstent: 0.5613 mL+/- 0.1019 mL) were not statistically significant (P > 0.05), but the differences to the theoretically possible volumes that we had previously calculated were highly significant (P < 0.05). Correlation and regression analyses demonstrated a significantly stronger relationship between stent volume and vessel diameter than between stent volume and degree of arteriosclerosis.

CONCLUSION

The modification of our ex vivo model of balloon-expandable stents now makes it possible for researchers to obtain comparable and realistic values for both the radial force and the expansion of self-expanding stents under realistic conditions. Our methods should therefore be employed as an additional procedure to optimize the preclinical evaluation of new stent during certification.

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

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

Current concepts of mechanical cerebral protection during precutaneous carotid intervention

Major advances in the endovascular treatment of carotid artery stenosis are underway, with an emphasis on improving the safety profile of the technique. This review highlights key areas in the concepts and design of available mechanical neuroprotection devices utilized during carotid stenting to minimize procedural cerebral embolization. The advantages and disadvantages of each system are explored and the available clinical experience is given. The size threshold of particulate material likely to be clinically relevant is examined and compared with pathological analysis of particles trapped by protection systems reported in the world literature. It is shown that the adverse neurological event rate in those protected is lower than that in historical studies of unprotected carotid stenting. Furthermore, the size range and numbers of particles trapped by protections systems are sufficient to cause potential neurological injury if allowed passage to the brain. Further improvements in outcomes may require further refinement of protection technology.

Endovascular Treatment of Internal Carotid Artery Stenosis: Effect of Primary Stent Application on Debris Particle Release in Human Cadaveric Specimens

PURPOSE

To compare debris release with primary stent application (self-expanding stent application at stenosis and then balloon dilation through the opened stent) and that with secondary stent application (balloon angioplasty of stenosis and afterward additional stent application) for high-grade internal carotid artery stenosis in human cadaveric specimens.

MATERIALS AND METHODS

Fresh human cadaveric internal carotid artery specimens were attached to a tube system. High-grade stenoses (>66%) were selected, randomized for primary or secondary stent application, and then treated, with fluoroscopic guidance, while the system was rinsed in a pulsating flow. Fluid was collected and filtered, and debris particles were examined with a light microscope. Particles were analyzed according to those consecutively caught by 100 x 100-microm and 11 x 11-microm mesh filters. Results were evaluated in relation to stent application. For statistical analyses of group differences, the exact Mann-Whitney U test was used.

RESULTS

Thirteen high-grade human cadaveric internal carotid artery stenoses were analyzed. Five specimens were randomly assigned to secondary stent application, and eight were assigned to primary stent application. No significant difference could be demonstrated for debris release with primary or secondary stent application. P values ranged from.051 to.754.

CONCLUSION

The reported superiority of primary stent application may not be related to debris reduction.

Carotid angioplasty in a pulsatile flow model: factors affecting embolic potential

OBJECTIVES

Carotid endoluminal intervention is an alternative to surgery but carries a risk of embolic stroke even with distal protection devices. We investigated the clinical features and degree of stenosis related to number and size of emboli during carotid angioplasty.

DESIGN

An experimental ex vivo study.

MATERIALS

An ex vivo pulsatile flow model was used in which temperature, velocity, flow, pressure and viscosity characteristics were designed to simulate the carotid circulation.

METHODS

Carotid endarterectomy specimens excised as intact cylinders (n = 28) were subjected to a standardised angioplasty procedure using radiological guidance. Emboli collected in filters placed distally were counted and sized using microscopy.

RESULTS

Median number of emboli during angioplasty was 133 (range 15-1331). Median size of the largest embolus was 700 microns (range 75-2400). Severity of stenosis correlated with increased maximum size (r = 0.55, p = 0.012). Statin therapy >4 weeks pre-operatively was associated with reduced emboli number and size (54 (range 15-748) vs 247 (range 37-1331) [p = 0.023] and 400 microm (range 75-2400) vs 1300 microm (range 600-2200) [p = 0.022]).

CONCLUSIONS

In this model a wide range of emboli number and size were produced. Number and size of embolic particles were highest in patients with high-grade stenoses not receiving statin therapy.

Carotid angioplasty and stent placement: a prospective analysis of perioperative complications and impact of intravenously administered abciximab

OBJECTIVE

To determine the frequency of perioperative complications since the introduction of abciximab, we prospectively evaluated our experience in a consecutive series of patients undergoing carotid angioplasty and stent placement (CAS). CAS has been introduced recently for treatment of carotid artery stenosis. A major limitation to this modality is the risk of perioperative thromboembolic and ischemic events. To reduce the risk of ischemic complications, abciximab, a platelet glycoprotein IIb/IIIa receptor inhibitor, has been introduced as adjunctive treatment for high-risk patients.

METHODS

Each patient was evaluated by a neurologist before, immediately after, and 24 hours after CAS for identification and classification of new neurological deficits. Bleeding events or other complications during hospitalization were recorded. Bleeding complications were classified as major (hemoglobin decrease,g5 g/dl), minor (hemoglobin decrease, 3-5 g/dl), or insignificant. Abciximab was administered intravenously as a single bolus (0.25 mg/kg) and then via infusion (10 microg/min) for 12 hours as an adjunct to CAS in patients considered to be at high risk for thromboembolic events owing to recent ischemic symptoms and/or complex lesion morphology.

RESULTS

Intravenously administered abciximab was used in 37 patients (mean age, 70 yr; 21 patients were men) as an adjunct to high-risk CAS. Thirty-three other patients underwent CAS performed with standard intraprocedural heparinization (mean age, 69 yr; 17 patients were men). Minor ischemic strokes were observed in 1 of 37 abciximab-treated patients and in 4 of 33 heparin-treated patients. No major ischemic strokes were observed in either group. Transient neurological deficits were observed in nine patients in the abciximab-treated group and in one patient in the heparin-treated group. Transient neurological deficits in abciximab-treated patients were mainly related to hemodynamic factors (associated with balloon inflation in two patients and with hypotension in another two patients) or occurred after completion of infusion (in three patients). Minor bleeding complications were observed in three patients who received abciximab and in four patients who received standard heparinization. Major bleeding complications were observed in four patients from each group. Two patients who received abciximab developed intracerebral hemorrhages; one hemorrhage was fatal.

CONCLUSION

The frequency of ischemic stroke in high-risk patients (3%) with the use of intravenously administered abciximab was lower, but not significantly so, than rates observed in lower-risk patients (12%), although the benefit was lost because of the high rate of intracranial hemorrhages (5%). Further efforts are required to determine appropriate selection criteria for use of intravenously administered abciximab and the effect of other strategies that involve distal protection devices.

Benefits of cerebral protection during carotid stenting with the PercuSurge GuardWire system: midterm results

PURPOSE

To examine the possible beneficial effect of a new cerebral protection device based on balloon occlusion of the distal internal carotid artery (ICA) and debris aspiration for patients undergoing carotid artery stenting (CAS).

METHODS

One hundred and eighty-four CAS procedures were attempted under cerebral protection using the PercuSurge GuardWire system in 167 patients (129 men; mean age 70.5 +/- 9.2 years, range 40-91)). The lesions were mainly atherosclerotic, and half (n = 93) were asymptomatic. Eighteen restenotic and 7 post-radiation stenoses were also treated.

RESULTS

Technical success was 99.5%. All lesions were stented except 3 postangioplasty restenoses. Prophylactic occlusion during balloon dilation and stenting was well tolerated in 176 (95.7%) patients. Microscopic analysis of the aspirated blood showed different types of particles numbering between 7 and 145 per procedure with a mean diameter of 250 microm (56-2652 microm). The 30-day stroke and death rate was 2.7%: 3 periprocedural complications at <48 hours (1 major stroke and 2 transient ischemic attacks), 1 intracerebral hemorrhage at 3 days, and 1 death of cardiac failure at 3 weeks.

CONCLUSIONS

This study yielded a favorably low rate of periprocedural embolic events comparable with standard CAS series. Protection devices may play an important role in future carotid interventions and expand the applicability of the procedure. Randomized studies (surgery versus CAS with and without cerebral protection) are awaited.

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

BACKGROUND AND PURPOSE

Histopathologic analysis was performed to better understand quantity, particle size, and composition of embolized debris collected in protection filters during carotid artery stent implantation.

METHODS

Elective carotid stent implantation with the use of a distal filter protection was attempted in 38 consecutive lesions (36 patients) of the internal carotid artery presenting >70% diameter stenosis (mean, 82.1+/-11.1%). Mean age of the patients was 70.7+/-7.7 years; 75% were men, and 50% of patients had previous neurological symptoms.

RESULTS

In 37 lesions (97.4%) it was possible to position the filter device, and in all lesions a stent was successfully implanted. The only complication occurring in the hospital and during the 30-day follow-up was 1 death due to acute myocardial infarction. Neurological sequelae did not occur. Histomorphometric analysis was performed on the filters. Presence of debris was detected in 83.7% of filters. The mean surface area of the polyurethane membrane filter covered with material was 53.2+/-19.8%. Particle size ranged from 1.08 to 5043.5 microm (mean, 289.5+/-512 microm) in the major axis and 0.7 to 1175.3 microm (mean, 119.7+/-186.7 microm) in the minor axis. Collected debris consisted predominantly of thrombotic material, foam cells, and cholesterol clefts.

CONCLUSIONS

By the use of distal protection filters during carotid artery stenting, it was possible to collect particulate debris potentially leading to distal vessel occlusion in a high percentage of cases. Qualitative analysis of embolized material showed debris dislocated during the percutaneous intervention from atheromatous plaques.

Cerebrovascular angioplasty and stenting for the prevention of stroke

Until recently, stroke preventive strategies have focused on either medical regimens aimed at antagonizing or reversing atherosclerosis, or surgical intervention for revascularization of the cerebrovascular system. However, with the advent of rapidly emerging microcatheterization techniques and technology, endovascular surgical revascularization of the brain is rapidly emerging as a powerful therapeutic modality. In particular, significant advances already have been made in revascularization of the extracranial carotid artery and many common anatomic sites of intracranial athero-occlusive disease, using special adaptations of conventional percutaneous angioplasty and stenting techniques. This paper reviews the cumulative experience with these emerging techniques, with a particular emphasis on clinical outcomes and future directions. It also reports the substantial cumulative institutional experience of the authors over the past 18 months with both extracranial carotid and intracranial artery stent-assisted carotid angioplasty.