Comparison of carotid stents: an in-vitro experiment focusing on stent design

Carotid stenting: Does stent design matter?

BACKGROUND

Carotid artery stenting (CAS) is considered an important tool in carotid revascularization. Carotid artery stenting is usually performed by using self-expandable stent with different designs. The stent design influences many physical characteristics. Also, it may affect the complication rate with special relevance to perioperative stroke, hemodynamic instability, and late restenosis.

METHODS

This study comprised all consecutive patients who underwent carotid artery stenting for atherosclerotic carotid stenosis from March 2014 to May 2021. Both symptomatic patient and asymptomatic patients were included. Patients with a symptomatic carotid stenosis of ≥50% or asymptomatic carotid stenosis of ≥60% were selected for carotid artery stenting . Patients with fibromuscular dysplasia and acute or unstable plaque were not included. Variables of clinical relevance were tested in multivariable analysis using binary logistic regression model.

RESULTS

A total of 728 patients were enrolled. The majority of this cohort was asymptomatic (578/728, 79.4%), while 150/728 (20.6%) were symptomatic. The mean degree of carotid stenosis was 77.82 ± 4.73%, with a mean plaque length of 1.76 ± 0.55 cm. A total of 277 (38%) patients were treated with Xact® Carotid Stent System. Successful carotid artery stenting was achieved in 698 (96%) of patients. Of these patients, stroke rate in symptomatic patients was nine (5.8%), while in asymptomatic patients was 20 (3.4%). In a multivariable analysis, the open-cell carotid stent was not associated with a differential risk for combined acute and sub-acute neurologic complications as compared with closed-cell stents. Patients treated with open cell stents had a significantly lower rate of procedural hypotension (P 0.0188) at bivariate analysis.

CONCLUSION

Carotid artery stenting is considered a safe alternative to CEA that can be used in selected average surgical risk patient. Different stent designs can affect the rate of major adverse events in carotid artery stenting patients, but further studies are necessary with avoiding different bias to study the effect of different stent designs.

Evaluation of the self-expanding effect of carotid stents in the early postoperative period

PURPOSE

To evaluate the expansion effect of self-expandable stents during the first week after carotid artery stenting (CAS) procedure and to examine the variation of the effect according to the carotid plaque type.

METHODS

Seventy stenotic carotid arteries of 69 patients were stented by using self-expanding Wallstents with diameters of 7 and 9 mm, after detection of stenosis and plaque type by Doppler ultrasonography. Post-stent aggressive ballooning was avoided and residual stenosis rates were measured with digital subtraction angiography. After the stenting procedure, the caudal, narrowest, and cranial diameters of stents were measured with ultrasonography at 30 min, first day and first week. Stent diameter increase and change according to plaque type were evaluated. Two-way repeated measure ANOVA test was used for statistical analysis.

RESULTS

A significant increase was observed in the mean stent diameter in the three stent regions (caudal, narrow, and cranial) from the 30th minute to the first and seventh days (p < 0.001). The most prominent stent expansion occurred in the cranial and narrow segments within the first day. In the narrow stent region; Stent diameter increase between 30th minute-first day, 30th minute-first week, and first day-first week were all significant (p < 0.001). At 30 min, first day, and first week, no significant difference was detected between plaque type and stent expansion in caudal, narrow, and cranial regions (p = 0.286).

CONCLUSION

We think that keeping the lumen patency limited to 30% residual stenosis after CAS procedure by applying minimal post-stenting balloon dilatation and leaving the remaining lumen expansion to the self-expanding feature of the Wallstent might be a sensible approach in order to avoid embolic events and excessive carotid sinus reactions (CSR).

The correlation between the cardiovascular instability and the size of the developed ischaemic lesions in patients who underwent carotid stenting

AIMS

In this study we investigated the relationship between cardiovascular instability and the size of the developed ischaemic lesions during carotid stent implantation by diffusion-weighted (DWI) magnetic resonance (MR) examination.

MATERIAL AND METHODS

We retrospectively analyzed anaesthesia reports and follow-up MR examinations after stent implantation of 192 patients in a 3-year period. Nineteen aspects of cardiovascular status were analyzed. We registered the duration of the intervention, low and high blood pressure (BP) values during anaesthesia and heart rates. The fluctuations of BP and heart rate and the time of their compensations after the stent expansion were also recorded. Values were compared with the number and the size of ischaemic lesions on DWI scans. We used Spearman and Kendall rank correlations and Welch's tests for statistical analysis. Values of p ≤ 0.05 were considered as statistically significant.

RESULTS

Decreased heart rate significantly correlated with the number (p = 0.0123) and size (p = 0.00323) of ischaemic lesions during stent expansion. Other cardiovascular parameters did not show any significant correlations.

CONCLUSIONS

Our results indicate that only heart rate attenuation affects the size of ischaemic lesions; thus the prevention of bradycardia is highly important.

The Effect of Stent Design on Plaque Protrusion after Carotid Artery Stenting

Objective

The association between stent design and post-stent intravascular findings after carotid artery stenting (CAS) was evaluated.

Methods

Among the 79 patients who underwent CAS between March 2016 and June 2020 at our institution, we retrospectively analyzed 65 patients with full post-stent intravascular evaluation by both optical frequency domain imaging and angioscopy. All CAS procedures were performed under the flow reversal method, and the stent selection was determined by each operator's discretion, depending on the vessel anatomy or plaque characteristics. The patient's characteristics, plaque characteristics, ischemic complication, and post-stent intravascular findings (plaque protrusion, vessel wall apposition of stent) were compared between the closed-cell and open-cell stent groups.

Results

The closed-cell group (n = 34) had more high-risk plaques, such as symptomatic lesions or intraplaque hemorrhages, on MRI compared with the open-cell group (n = 31). There was no difference in the rate of ischemic complications between the groups. Although there was no difference in the frequency of plaque protrusion between the two, the maximum height of the protruded plaque was higher in the open-cell group (320 vs. 612 μm, p = 0.003) and incomplete apposition was higher in the closed-cell group (85.3 vs. 6.5%, p <0.0001).

Conclusion

The open-cell stent provided better apposition but had larger plaque protrusion. The need for a new hybrid stent that combines the merits of both open- and closed-cell stents was suggested.

Incidence and predictors of prolonged hemodynamic depression after carotid artery stenting: Yet another benefit of statins?

OBJECTIVES

We aimed to assess the incidence and predictors of prolonged hemodynamic depression (PHD) after carotid artery stenting (CAS).

METHODS

We retrospectively analyzed data from 216 CAS procedures performed in 207 patients (156 male; median and interquartile range (IQR) of age 68 (62-73) yr) between July 2012 and October 2020. PHD was defined as hypotension (systolic blood pressure ≤ 90 mmHg) and/or bradycardia (heart rate < 60 bpm) lasting >1 h.

RESULTS

The incidence of PHD was 25.9%. At multivariate analysis, asymptomatic lesions (OR: 2.43, 95% CI (1.16-5.06), p: 0.018), the stenosis proximity (<10 mm) to bifurcation (OR: 2.94, 95% CI (1.34-6.43), p: 0.007) and implantation of a Protege stent (OR: 2.93, 95% CI (1.14-7.53), p: 0.025) were independent risk factors, while statin usage (OR: 0.48, 95% CI (0.24-0.95), p: 0.036) was an independent protective factor for PHD after CAS.

CONCLUSIONS

Patients with asymptomatic lesions and stenosis close to the bifurcation are more prone to PHD. The type of the stent selected significantly influences the risk of PHD. Further prospective randomized studies are warranted to investigate the possible protective role of statins against PHD after CAS.

Prevention of Stroke with Closed-Cell Stent-in-Stent for Carotid Artery Stenosis Due to Stent Fracture

Objective

Stent fracture is a risk factor for stroke. It has not been fully elucidated whether stent-in-stent procedures can effectively treat stent fractures.

Case Presentation

An 80-year-old man underwent carotid artery stenting (CAS) with an open-cell stent to treat asymptomatic right internal carotid artery (ICA) stenosis. Type III stent fracture occurred during CAS. Six months later, in-stent stenosis progressed on DSA. Repeat CAS with a closed-cell stent was performed. CT showed expansion of the narrowed lumen. The patient remained stroke-free and carotid artery restenosis did not occur for 3 years postoperatively.

Conclusion

Repeat CAS with a closed-cell stent is a viable treatment option for stent fracture.

Emergent carotid artery stenting for cervical internal carotid artery injury during carotid endarterectomy: A case report

Background:

Carotid endarterectomy (CEA) has been the standard preventive procedure for cerebral infarction due to cervical internal carotid artery stenosis, and internal shunt insertion during CEA is widely accepted. However, troubleshooting knowledge is essential because potentially life-threatening complications can occur. Herein, we report a case of cervical internal carotid artery injury caused by the insertion of a shunt device during CEA.

Case Description:

A 78-year-old man with a history of hypertension, diabetes, and hyperuricemia developed temporary left hemiplegia. A former physician had diagnosed the patient with a transient cerebral ischemic attack. The patient’s medical history was significant for the right internal carotid artery stenosis, which was severe due to a vulnerable plaque. We performed CEA to remove the plaque; however, there was active bleeding in the distal carotid artery of the cervical region after we removed the shunt tube. Hemostasis was achieved through compression using a cotton piece. Intraoperative digital subtraction angiography (DSA) revealed severe stenosis at the internal carotid artery distal to the injury site due to hematoma compression. The patient underwent urgent carotid artery stenting and had two carotid artery stents superimposed on the injury site. On DSA, extravascular pooling of contrast media decreased on postoperative day (POD) 1 and then disappeared on POD 14. The patient was discharged home without sequela on POD 21.

Conclusion:

In the case of cervical internal carotid artery injury during CEA, hemostasis can be achieved by superimposing a carotid artery stent on the injury site, which is considered an acceptable troubleshooting technique.

The Geometry of Y-Stent Configurations Used for Wide-Necked Aneurysm Treatment: Analyzing Double-Barrel Stents In Vitro Using Flat-Panel Computed Tomography

BACKGROUND

Stent-assisted coil embolization of wide-necked bifurcation aneurysms often employs a Y configuration stent. A similar stent configuration, termed kissing/double-barrel (KDB), is used often at the aortoiliac bifurcation. Studies of KDB stents in aortoiliac disease show that rates of thromboembolic complications vary with the cross-sectional geometry of the stent pair, a function of the radial crush resistive force of each stent. We assessed cross-sectional geometry of intracranial stent pairs in an in vitro model of the basilar artery using flat-panel computed tomography.

METHODS

In a silicone model of a wide-necked basilar tip aneurysm, 6 simulated KDB stent deployment trials were performed using combinations of 5 stents (Enterprise 1, Enterprise 2, Neuroform Atlas, LVIS, LVIS Jr.). Flat-panel computed tomography reconstructions were used to assess cross-sectional stent geometry. Relative conformability, defined by ovalization and D-ratio, radial crush resistive force (predicted vs. actual), and radial mismatch fraction were compared by stent type (braided vs. laser-cut).

RESULTS

Several distinct forms of cross-sectional stent geometry were observed. Braided stents had lower ovalization and D-ratio (P = 0.015) than laser-cut stents. The Neuroform Atlas/LVIS combination yielded the lowest radial mismatch fraction (19.7% vs. mean 44.3% ± 0.7%). Braided stents tended to have a deployed stent radius closer to the expected (nominal) diameter (i.e., higher relative crush resistive force) than laser-cut stents (measured vs. nominal diameter discrepancy +38.6% ± 21.1% vs. -10.7% ±16.1%, P = 0.14).

CONCLUSIONS

In constant anatomy, cross-sectional geometry of the KDB stent configuration will vary depending on the design and structure of the stents employed.

Comparison of open- and closed-cell stent design outcomes after carotid artery stenting in the Vascular Quality Initiative

BACKGROUND

The association between stent design and outcomes after carotid artery stenting (CAS) has remained controversial. The available data are conflicting regarding the superiority of any specific stent design. The present study investigated the association between cell design and outcomes after carotid artery stenting (CAS) in a real world setting.

METHODS

Patients who had undergone CAS with distal embolic protection in the Society for Vascular Surgery Vascular Quality Initiative (VQI) database from 2016 to 2018 were included in the present study. Patients undergoing CAS for trauma or dissection or more than two treated lesions were excluded. We also excluded lesions for which more than two carotid stents had been used and lesions confined to the common or external carotid artery. Univariable and multivariable logistic regression analyses were used to compare the outcomes after CAS between the open- and closed-cell stent designs.

RESULTS

Of the 2671 CAS procedures included in the present analysis, 1384 (51.8%) had used closed-cell stents and 1287 (48.2%) had used open-cell stents. On univariable analysis, no significant differences were noted between the closed- and open-cell stents in in-hospital mortality (1.8% vs 1.4%; P = .40), stroke (1.8% vs 2.4%; P = .28), and stroke/death (3.3% vs 3.5%; P = .81). After adjusting for potential confounders (ie, age, symptomatic status, previous major amputation, statin and antiplatelet use, American Society of Anesthesiologists class, elective procedures, approach, and post-stent dilatation), no difference was noted in in-hospital stroke/death between the two stent designs (odds ratio [OR], 1.08; 95% confidence interval [CI], 0.68-1.74; P = .74). However, the interaction between stent design (open vs closed) and lesion location (bifurcation vs internal carotid artery [ICA]) was statistically significant (P = .02). Closed-cell stents were associated with five times the odds of in-hospital stroke/death when used in carotid artery bifurcation (OR, 5.5; 95% CI, 1.3-22.2; P = .02). However, when the stent was limited to the ICA, no differences were noted (OR, 0.87; 95% CI, 0.51-1.45; P = .62). One-year follow-up data were available for 19% of patients. No differences in ipsilateral stroke or death at 1 year were noted between the open- and closed-cell stents, except when the lesion was located in the carotid bifurcation (hazard ratio, 6.7; 95% CI, 1.4-31.4; P = .02).

CONCLUSIONS

Closed-cell stents were associated with an increased odds of in-hospital stroke/death for carotid bifurcation lesions, which might be related to the relatively lower conformability of closed-cell stents in the tortuous and diameter-mismatched bifurcation anatomy vs the relatively linear uniform diameter of the ICA. Improved follow-up and in-depth analysis of lesion-specific characteristics that might influence the outcomes of these two designs are needed to validate these results.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Clinical trial of carotid artery stenting using dual-layer CASPER stent for carotid endarterectomy in patients at high and normal risk in the Japanese population

BACKGROUND

The dual-layer nitinol CASPER stent was designed to prevent plaque prolapse into its strut and periprocedural stroke.

OBJECTIVE

To conduct a clinical trial for government approval of the device in patients at either high or normal risk for carotid endarterectomy (CEA).

METHODS

Eligible patients had ≥50% symptomatic stenosis or ≥80% asymptomatic stenosis according to the North American Symptomatic Carotid Endarterectomy Trial methods (peak systolic velocity 130 and 230 cm/s on ultrasonography, respectively). The primary endpoint was the lack of major adverse events (MAEs), defined as death, stroke, and myocardial infarction within 30 days, and ipsilateral stroke within 1 year. The performance goal was set at 90.5%. MAE rates were also compared between the CEA high- and normal-risk groups.

RESULTS

140 carotid artery stenting procedures, including 40% of patients at high risk and 60% at normal risk for CEA, were performed in 13 institutes. MAEs occurred in two cases (one intraprocedural and one postprocedural stroke), and the MAE rate was 1.4%. The non-MAE rate was 98.6% according to Kaplan-Meier analysis, which was superior to the previously set performance goal. The deployment success, target lesion revascularization (TLR), in-stent restenosis, and cerebrovascular event rates were 99.3%, 2.4%, 8.5%, and 7.2%, respectively. The MAE rate in patients with normal CEA risk was 1.2%, which was similar to the high-risk CEA group, with no significant difference due to the small number of MAEs.

CONCLUSIONS

The MAE rate following use of the CASPER stent was low (1.4%). The MAE, deployment success, TLR, in-stenosis, and cerebrovascular event rates were similar to those of previous reports.

(In)comparability of Carotid Artery Stent Characteristics: A Systematic Review on Assessment and Comparison with Manufacturer Data

Purpose

Carotid stent (CS) characteristics, such as radial force, scaffolding and flexibility, are continuously modified by stent manufacturers aiming to improve stent performance. Since manufacturers’ definitions and assessment methods are not disclosed, it is unknown how characteristics of different CSs relate to each other or to published literature. We examined in vitro methodological techniques used to measure CS characteristics and assessed comparability between published papers and outcomes as provided by the manufacturers.

Methods

A systematic review was conducted in MEDLINE, Embase, Cochrane, and Scopus databases. Studies reporting on in vitro investigations of predefined characteristics of CS used in current everyday clinical practice were included. The predefined characteristics were radial force, scaffolding, flexibility, foreshortening, side-branch preservation and visibility. Eight manufacturers of 10 currently used CS were contacted and data on the predefined device characteristics was requested.

Results

12 published articles were included and six stent manufacturers provided data on six stents (two refused to share data). Used methodologies to measure stent characteristics in published literature and manufacturer data varied greatly for all included characteristics except foreshortening. The number of different units of measurement to express outcomes ranged from two for foreshortening to six for radial force.

Conclusion

A variety of methodologies and outcome measures is used to quantify CS characteristics, which hampers comparisons between published studies and manufacturer data. Future studies are encouraged to synchronize methodologies and outcome measures. Manufacturers are encouraged up to increase transparency of applied testing methodologies and outcomes.

Electronic supplementary material

The online version of this article (10.1007/s00270-020-02499-1) contains supplementary material, which is available to authorized users.

Multivariable Analysis of Patients With Severe Persistent Postprocedural Hypotension After Carotid Artery Stenting

Purpose: To assess the incidence and predictors of severe, persistent postprocedural hypotension (PPH) after carotid artery stenting (CAS). Materials and Methods: A total of 146 patients (mean age 72.8 years; 104 men) who underwent 160 CAS procedures using a standardized protocol at 3 vascular centers were retrospectively analyzed. The primary endpoint was postprocedural hypotension, defined as a reduction in systolic blood pressure (SBP) >40 mm Hg from baseline or an SBP of <90 mm Hg sustained for >1 hour after CAS. Potential prognostic factors for postprocedural hypotension were identified and subjected to logistic regression analyses; outcomes are presented as the odds ratios (ORs) with 95% confidence intervals (CIs). Results: PPH developed in 36 (24.7%) patients after 37 (23.1%) CAS procedures. These patients had significantly longer intensive care unit and hospital stays than those who did not develop hypotension (p<0.001). PPH was associated with severe lesion calcification (OR 6.28, 95% CI 1.81 to 21.98, p=0.004) and contrast volume (OR 1.02, 95% CI 1.01 to 1.02, p<0.001). A 4-fold increase in the risk of PPH (OR 4.22, 95% CI 1.38 to 13.33, p=0.012) was found between the embolic protection device most associated with PPH (Angioguard) and the device least associated with PPH (Emboshield NAV6). A similar trend was also observed for the Precise vs Xact stents (OR 6, 95% CI 2.08 to 17.6, p=0.001). Bootstrapped multivariable modeling identified the Precise stent and contrast volume as significant predictors of persistent postprocedural hypotension. Further investigation of the contrast volume revealed associations with sex, severe calcification, arch type, previous coronary artery bypass surgery, and primary stenting, suggesting that the contrast volume reflects the complexity of the procedure. Conclusion: The complexity of the procedure and type of stent may play a role in the development of postprocedural hypotension after CAS.

Initial Clinical Results and In Vitro Testing of the New CGuard MicroNet-Covered "One-Size-Fits-All" Carotid Stent

Purpose: To evaluate a MicroNet-covered stent designed for the carotid artery with the new ability to adjust to different vessel diameters. Materials and Methods: Thirty consecutive patients (mean age 72.1±7.7 years; 26 men) with symptomatic stenosis (86.3%±6.4%) of the internal carotid artery were treated with the new self-adjusting nitinol stent, which has a self-expanding, open-cell design covered by an outer conformable layer (MicroNet). The only stent used was the "One-Size-Fits-All" CGuard stent with lengths of 30 or 40 mm. In bench testing, the chronic outward force of the One-Size-Fits-All stent was determined with a segmented head radial force test device. The stent was deployed directly into the test device at a diameter of 5.0 mm, and the chronic outward force was measured up to 10.0 mm, the maximum expansion of the stent. Results: The stent was successfully implanted in all 30 patients without periprocedural complications, including no neurological events within 30 days. The chronic outward force normalized by stent length demonstrated a near-equivalent radial force outcome: The stent displayed only a minor difference between the minimal radial force at 9.0 mm (0.195 N/mm) and the maximal radial force at 5.5 mm (0.330 N/mm). Conclusion: The new self-adjusting, MicroNet-covered stent has high conformability combined with an almost equivalent radial force at expansion diameters ranging from 5.5 to 9.0 mm. The first clinical results demonstrate that the new One-Size-Fits-All stent can be safely implanted in internal carotid arteries with reference diameters within this range.

Efficacy of post-dilatation during carotid artery stenting for unstable plaque using closed-cell design stent evaluated by optical coherence tomography

BACKGROUND AND PURPOSE

This study aimed to use optical coherence tomography (OCT) to evaluate the efficacy of post-dilatation (PD) after stent placement for unstable plaques during carotid artery stenting (CAS) using closed-cell design stent.

MATERIALS AND METHODS

Twelve unstable carotid plaque lesions diagnosed by magnetic resonance imaging were evaluated by OCT during CAS. Pre-procedural minimum lumen diameter and area were 1.5 ± 0.6 mm and 2.6 ± 1.6 mm², respectively. The lesion was pre-dilated with balloon catheters (diameter 4.8 ± 0.3 mm), and closed-cell stent was deployed. PD was performed with balloon catheters of the same size as those used for pre-dilatation. Minimum lumen diameter/area and in-stent tissue prolapse volume after stent placement and after PD were calculated by 2-dimensional cross section images. The number of the stent cells showing tissue prolapse and malapposition after stent-placement and after PD were calculated by 3-dimensional analysis.

RESULTS

Compared to after stent placement, in-stent tissue prolapse volume (0.18 ± 0.10 to 0.22 ± 0.07 mm²/slice, P < 0.01), number of stent cells with any tissue prolapse (12.7 ± 8.2 to 21.0 ± 11.8%, P < 0.001) were significantly increased after PD; stent cells with ≥ 500-µm tissue prolapse (1.6 ± 1.1 to 0.7 ± 0.8%, P < 0.01) and stent malapposition (17.4 ± 7.2 to 14.0 ± 6.3%, P < 0.01) were significantly decreased.

CONCLUSIONS

PD after carotid stent placement caused increase in in-stent tissue prolapse volume and small tissue prolapse, however, the in-stent large tissue prolapse decreased, as the in-stent tissue prolapse may have been crushed into debris.

Influence of stenting with open-cell stents vs close-cell stents on the outcomes of patients with bilateral carotid stenosis

BACKGROUND

Carotid artery stenting (CAS) is an effective way to prevent stroke in patients with severe carotid stenosis. However, several studies comparing the outcomes of stenting with open-cell stents (OCS) vs closed-cell stents (CCS) have yielded inconclusive results. This study aimed to compare the outcomes of CAS with OCS vs CCS in the same patients.

METHODS

From year 2000 to 2016, we included 52 patients with severe bilateral carotid stenosis who underwent OCS deployment in one artery and CCS deployment in the contralateral artery. Stents were selected according to arterial anatomy and lesion morphology, and the peri-procedural and long-term outcomes of treatment with OCS vs CCS, were compared in terms of rates of ischemic spot development on early post-procedural diffusion-weighted imaging (ISDWI), in-stent restenosis (ISR), and recurrent stroke.

RESULTS

After stenting with OCS vs CCS, the number (rate) of arteries with no lesion, < 5 lesions, and ≥ 5 lesions on DWI was 9 (32%) vs 8 (27%), 8 (29%) vs 17 (57%), and 11 (39%) vs 5 (17%) (p = .10); number (rate) of arteries with 0%, < 50%, and >50% ISR was 34 (65%) vs 34 (65%), 9 (17%) vs 11 (21%), and 9 (17%) vs 7 (13%) (p = .71); number (rate) of recurrent strokes after CAS was 2 (4%) vs 0 (0%).

CONCLUSION

The rates of peri-procedural cerebral ischemic insult, long-term stent patency, and stroke recurrence indicate that no one carotid stent cell design is superior to the other. We suggest both OCS and CCS are reasonable options for the treatment of severe carotid stenosis.

How to Escape Stentriever Wedging in an Open-cell Carotid Stent during Mechanical Thrombectomy for Tandem Cervical Internal Carotid Artery and Middle Cerebral Artery Occlusion

We present 2 cases of complicated mechanical thrombectomy involving tandem cervical internal carotid artery and middle cerebral artery occlusion using the Solitaire FR stent and simultaneous carotid stent angioplasty. During the procedures, the Solitaire stents containing the thrombus were wedged into the open-cell carotid stents, which were already deployed for proximal flow restoration. We describe the methods used to avoid and overcome such complications.

Comparison of closed-cell and hybrid-cell stent designs in carotid artery stenting: clinical and procedural outcomes

Introduction

Carotid artery stenting (CAS) is a promising alternative to surgery in high-risk patients. However, the impact of stent cell design on outcomes in CAS is a matter of continued debate.

Aim

To compare the periprocedural and clinical outcomes of different stent designs for CAS with distal protection devices.

Material and methods

All CAS procedures with both closed- and hybrid-cell stents performed at our institution between February 2010 and December 2015 were analyzed retrospectively. Adverse events were defined as death, major stroke, minor stroke, transient ischemic attack and myocardial infarction. Periprocedural and 30-day adverse events and internal carotid artery (ICA) vasospasm rates were compared between the closed-cell and hybrid-cell stent groups.

Results

The study included 234 patients comprising 146 patients with a closed-cell stent (Xact stent, Abbott Vascular) (mean age: 68.5 ±8.6; 67.1% male) and 88 patients with a hybrid-cell stent (Cristallo Ideale, Medtronic) (mean age: 67.2 ±12.8; 68.2% male). There was no significant difference between the groups with respect to periprocedural or 30-day adverse event rates. While there was no difference in terms of tortuosity index between the groups, there was a higher procedural ICA vasospasm rate in the closed-cell stent group (35 patients, 23%) compared with the hybrid-cell stent group (10 patients, 11%) (p = 0.017).

Conclusions

The results of this study showed no significant difference in the clinical adverse event rates after CAS between the closed-cell stent group and the hybrid-cell stent group. However, procedural ICA vasospasm was more common in the closed-cell stent group.

NUMERICAL INVESTIGATIONS OF THE FLEXIBILITY OF INTRAVASCULAR BRAIDED STENT

Braided stents are commonly used to treat cerebral aneurysm, but there is little information about the bending characteristic of braided stent used for cerebral aneurysm. This paper investigates how geometrical parameters of braided stent influence its flexibility. Eight groups of braided stent models with different geometries (i.e., nominal diameter, length, braiding angle, number of wires, diameter of wire, frictional coefficient among wires and porosity) were constructed. Parametric analyses of these models were carried out by using Abaqus/Explicit. When the nominal diameter varied from 2[Formula: see text]mm to 5.5[Formula: see text]mm, the forces required for flexural deformation decrease from [Formula: see text][Formula: see text]N to [Formula: see text][Formula: see text]N; when the axial length varied from 10[Formula: see text]mm to 40[Formula: see text]mm, the forces required for flexural deformation decrease from [Formula: see text][Formula: see text]N to [Formula: see text][Formula: see text]N; when the braiding angle increases from 30[Formula: see text] to 75[Formula: see text] (the number of wires is 48 and the diameter of the wire is 0.026[Formula: see text]mm), the forces required for bending deformation decrease from [Formula: see text][Formula: see text]N to [Formula: see text][Formula: see text]N; when the diameter of wires increases from 0.026[Formula: see text]mm to 0.052[Formula: see text]mm (the number of wires is 24 and the braiding angle is 60[Formula: see text]), the forces required for flexural deformation increase from [Formula: see text][Formula: see text]N to [Formula: see text][Formula: see text]N; and when the number of wires increases from 14 to 48 (the braiding angle is 75[Formula: see text] and the diameter of the wire is 0.026[Formula: see text]mm), the forces required for flexural deformation increase from [Formula: see text][Formula: see text]N to [Formula: see text][Formula: see text]N. From the data above it can be seen that the diameter of wires, the number of wires and braiding angle have a larger impact on bending characteristics of braided stent; and the axial length and nominal diameter have a smaller impact on bending characteristics of braided stent. Results of the present study may provide theoretical guidance for the design of self-expanding braided stent and its clinical practice.

Optical coherence tomography evaluation of tissue prolapse after carotid artery stenting using closed cell design stents for unstable plaque

BACKGROUND AND PURPOSE

During carotid artery stenting (CAS) with the use of closed cell design stents for unstable plaques, tissue prolapse between stent struts was evaluated by optical coherence tomography (OCT).

METHODS

14 carotid stenosis lesions diagnosed as unstable plaques by MRI were evaluated by OCT imaging during CAS using closed cell stents. Cross sectional OCT images within the stented segment were evaluated at 1 mm intervals. The slice rate for the presence of tissue prolapse between the struts was calculated.

RESULTS

No intra-procedural complications occurred. After single stent placement, plaque prolapse was observed in all cases. Slices with any and >500 µm tissue prolapse were seen in 30% and 7.8% of cases, respectively. In 5 of 7 lesions with tissue prolapse >500 µm, additional stents were overlapped. In cases with overlapping stents, slices with any tissue prolapse were significantly decreased from 26% to 16% (p=0.008); in particular, the occurrence of tissue prolapse >500 µm was significantly decreased from 15% to 2.3% (p<0.001). In one case of >500 µm tissue prolapse without an overlapping stent, delayed embolization due to an in-stent thrombus occurred 9 months after the procedure.

CONCLUSIONS

OCT during CAS using closed cell stent for unstable plaques frequently revealed tissue prolapse between struts. Placement of overlapping stents significantly reduced tissue prolapse, particularly tissue prolapse >500 µm. However, closed cell stents used for unstable plaques may not solve the problem of tissue prolapse.

Bench-top Comparison of Physical Properties of 4 Commercially-Available Self-Expanding Intracranial Stents

PURPOSE

To better understand the performance of four commercially available neurovascular stents in intracranial aneurysm embolization, the stents were compared in terms of their basic morphological and mechanical properties.

MATERIALS AND METHODS

Four different types of stents that are currently being used for cerebral aneurysm embolization were prepared (two stents per type). Two were laser-cut stents (Neuroform and Enterprise) and two were braided from a single nitinol wire (LEO and LVIS stents). All were subjected to quantitative measurements of stent size, pore density, metal coverage, the force needed to load, push, and deploy the stent, radial force on deployment, surface roughness, and corrosion resistance.

RESULTS

Compared to their nominal diameters, all stents had greater diameters after deployment. The length generally decreased after deployment. This was particularly marked in the braided stents. The braided stents also had higher pore densities than the laser-cut stents. Metal coverage was highest in the LEO stent (14%) and lowest in the Enterprise stent (5%). The LIVS stent had the highest microcatheter loading force (81.5 gf). The LEO stent had the highest passage force (55.0 gf) and deployment force (78.9 gf). The LVIS and LEO stents had the highest perpendicular (37.1 gf) and circumferential (178.4 gf) radial forces, respectively. The Enterprise stent had the roughest stent wire, followed by the LVIS, LEO, and Neuroform stents.

CONCLUSION

The four neurovascular stent types differed in terms of morphological and physical characteristics. An understanding of this diversity may help to decide which stent is most suitable for specific clinical situations.

Incidence and risk factors of embolized particles in carotid artery stenting and association with clinical outcome

BACKGROUND

One of the mechanisms for periprocedural neurologic events in carotid artery stenting (CAS) is catheter manipulation within the aorta and supraaortic arteries causing plaque embolization. Therefore, the present analysis sought to determine risk factors for embolic particle dimensions and their relationship with adverse clinical events after CAS.

METHODS

Between 1999 and 2015 embolic protection devices (EPD) of a total of 944 CAS procedures were evaluated regarding the occurrence and size of captured particles.

RESULTS

Particles were found in 819 of 944 (87%) EPDs. Larger particles were detected in procedures using open cell stents (150±282μm vs. 107±177μm; p=0.005) and longer stents (≥40mm) (165±315μm vs. 122±215μm; p=0.026). With increasing learning curve, particle size was continually reduced (168±282μm in the first third of the cohort vs. 127±309μm in the second third vs. 108±114μm in the last third; p=0.009). Longer stents and use of Acculink stent were found to be independent predictors for particle diameter. In patients who died or sustained a stroke during long-term follow-up (median 5.5years [IQR 2.6-7.9]) significantly larger particles were captured during CAS compared to those patients with an uneventful follow-up (160±330μm vs. 121±195μm; p=0.047).

CONCLUSIONS

In the vast majority of CAS procedures particles could be retrieved from the EPDs used. Procedural characteristics such as stent type and stent length were associated with larger particles.

Clinical Results and Mechanical Properties of the Carotid CGUARD Double-Layered Embolic Prevention Stent

Purpose: To report early clinical outcomes with a novel double-layer stent for the internal carotid artery (ICA) and the in vitro investigation of the stent’s mechanical properties. Methods: A prospective single-center study enrolled 30 consecutive patients (mean age 73.1±6.3 years; 21 men) with symptomatic (n=25) or high-grade (n=5) ICA stenosis treated with the new double-layer carotid CGUARD Embolic Prevention System (EPS) stent, which has an inner open-cell nitinol design with an outer closed-cell polyethylene terephthalate layer. The average stenosis of the treated arteries was 84.1%±7.9% with a mean lesion length of 16.6±2.1 mm. In the laboratory, 8×40-mm stents where tested in vitro with respect to their radial force during expansion, the bending stiffness of the stent system and the expanded stent, as well as the collapse pressure in a thin and flexible sheath. The wall adaptation was assessed using fluoroscopy after stent release in step and curved vessel models. Results: The stent was successfully implanted in all patients. No peri- or postprocedural complications occurred; no minor or major stroke was observed in the 6-month follow-up. The bending stiffness of the expanded stent was 63.1 N·mm2 and (not unexpectedly) was clearly lower than that of the stent system (601.5 N·mm2). The normalized radial force during expansion of the stent to 7.0 mm, consistent with in vivo sizing, was relatively high (0.056 N/mm), which correlates well with the collapse pressure of 0.17 bars. Vessel wall adaptation was harmonic and caused no straightening of the vessel after clinical application. Conclusion: Because of its structure, the novel CGUARD EPS stent is characterized by a high flexibility combined with a high radial force and very good plaque coverage. These first clinical results demonstrate a very safe implantation behavior without any stroke up to 6 months after the procedure.

Prediction of Prolonged Hemodynamic Instability During Carotid Angioplasty and Stenting

Purpose

The aim of this study was to assess the risk factors of prolonged hemodynamic instability (HDI) after carotid angioplasty and stenting (CAS). Herein, a simplified predictive scoring system for prolonged HDI is proposed.

Materials and Methods

Sixty-six patients who had CAS from 2011 to 2016 at a single institution were evaluated. Prolonged HDI was defined as systolic blood pressure >160 mm Hg or <90 mm Hg or heart rate <50 beats/min, lasting over 30 minutes despite medical treatments. For the study, clinical data and radiologic data, including plaque morphology and stenosis were analyzed.

Results

Prolonged HDI was observed in 21 patients (31.8%). Multivariable analysis revealed that calcification (OR, 6.726; p=0.006), eccentric stenosis (OR, 3.645; p=0.047) and extensive plaque distribution (OR, 7.169; p=0.006) were related to prolonged HDI. According to these results, a simplified scoring scale was proposed based on the summation of points: 2 points for calcified plaque, 2 points for extensive plaque distribution, and 1 point for eccentric stenosis. The percentages of prolonged HDI according to the total score were as follows: score 0, 8.7%; score 1, 20.0%; score 2, 38.5%; score 3, 72.7%; score 4, 66.7%; score 5, 100%. From the analysis, the total score in patients with prolonged HDI was significantly higher than those without prolonged HDI (p<0.001).

Conclusion

Prolonged HDI can be associated with calcification of plaque, eccentric stenosis and extensive plaque distribution, and a simplified scoring system enables prediction of prolonged HDI according to our cohort.

Carotid artery stenting with a new-generation double-mesh stent in three high-volume Italian centres: clinical results of a multidisciplinary approach

AIMS

Carotid artery stenting (CAS) is still associated with higher periprocedural cerebrovascular events (CEs) compared to vascular surgery. The Roadsaver carotid artery stent is a double layer micromesh stent which reduces plaque prolapse and embolisation by improving plaque coverage. Its clinical impact on neurological outcome was unknown. The aim of this study was therefore to report the clinical results of a large real-world population from three different centres receiving a Roadsaver stent to treat carotid artery disease.

METHODS AND RESULTS

One hundred and fifty (150) patients (age 74±8 yrs, 75% male, symptomatic 29%) treated with CAS using the Roadsaver carotid stent in three high-volume Italian centres were included in the study. Intraprocedural optical coherence tomography (OCT) evaluation was performed in 26 patients, with an off-line analysis by a dedicated core laboratory. All patients underwent duplex ultrasound and neurological evaluation at 24 hours and at 30 days. CAS was technically successful in all cases (stent diameter: 8.6±0.8 mm, stent length: 25.0±4.5 mm). No in-hospital or 30-day CEs were observed. OCT evaluation detected a low rate of plaque prolapse (two patients, 7.7%). Duplex ultrasound showed stent and external carotid artery patency in all cases both before discharge and at 30-day follow-up.

CONCLUSIONS

The Roadsaver stent is a safe and promising technology for CAS, with a low percentage of plaque prolapse and good short-term clinical outcome. Larger studies with longer follow-up are necessary to confirm this favourable clinical outcome.

Simulated Bench Testing to Evaluate the Mechanical Performance of New Carotid Stents

Our group recently developed a novel covered carotid stent that can prevent emboli while preserving the external carotid artery (ECA) branch blood flow. However, our recent in vitro side-branch ECA flow preservation tests on the covered stents revealed the need for further stent frame design improvements, including the consideration to crimp the stent to a low profile for the delivery of the stent system and having bigger cells. Hence, the current work aims to design new bare metal stents with bigger cell size to improve the crimpability and to accommodate more slits so that the side-branch flow could be further increased. Three new stent designs were analyzed using finite element analysis and benchmarked against two commercially available carotid stents in terms of their mechanical performances such as crimpability, radial strength, and flexibility. Results indicated that the new bare metal stent designs matched well against the commercial stents. Hence our new generation covered stents based on these designs can be expected to perform better in side-branch flow preservation without compromising on their mechanical performances.

Preliminary Clinical Results and Mechanical Behavior of a New Double-Layer Carotid Stent

PURPOSE

To evaluate the in vitro mechanical and clinical implant behavior of a next-generation double-layer stent designed for the carotid artery.

METHODS

The new double-layer CASPER-RX stent was implanted in 12 patients (median age 69 years; 8 men) with high-grade symptomatic internal carotid artery stenoses (mean 82%). In the in vitro experiments, the CASPER-RX stent (8-×40-mm model) was investigated with respect to its radial force on expansion and the bending stiffness of the stent system and of the stent in its expanded state, as well as the collapse pressure in a thin, flexible sleeve. The wall adaptation of the expanded stents was assessed by fluoroscopy after release in a step and curve model.

RESULTS

Technical success was achieved in all patients without complications; there was no peri- or postinterventional stroke and no stroke or restenosis after 6 months. In the experimental studies, the bending stiffness of the stent on the delivery system (154.9 N mm(2)) was significantly lower than when expanded in a 7-mm flexible tube (467.4 N mm(2)). The radial force on expansion of the stent to 7 mm was low (0.011 N/mm). The collapse pressure was relatively high (0.56 bar) as a result of the stent's particular stent structure. The stent exhibited significant foreshortening of 27.6%. The conformability to the wall in the step model was relatively smooth; in the curve model, straightening occurred with consecutive slight stenosis.

CONCLUSION

The first clinical results showed a safe implantation behavior without the occurrence of any ischemia. The structure of the new CASPER-RX stent creates an acceptable flexibility, low radial force, and high collapse pressure. The large foreshortening during implantation should be considered as well as the higher bending stiffness, especially when used in elongated carotid arteries.

The Effect of Stent Cell Geometry on Carotid Stenting Outcomes

PURPOSE

The aim of this study was to investigate the effect of stent cell geometry on midterm results of carotid artery stenting (CAS).

MATERIALS AND METHOD

One hundred fifty-five patients underwent CAS between February 2010 and December 2012. Ninety-one open- and 84 closed-cell stents were used in this non-randomized, retrospective study. Periprocedural complications were defined as the ones happened during the procedure or within 30 days afterwards. Starting from the 6th month after the procedure, in-stent restenosis was detected with multidetector computed tomography angiography and classified into four groups from focal restenosis to occlusion.

RESULTS

Eleven complications were encountered in the periprocedural period (four on the open- and seven on the closed-cell group). Total complication rate was 6.3% (11/175). No significant difference was detected in terms of periprocedural complications between two groups (p = 0.643). There was statistically significant difference between stent design groups in regard to radiological findings (p = 0.002). Sixteen of open-cell stents and three of closed-cell stents had focal restenosis. One closed-cell stent had diffuse proliferative restenosis and one open-cell stent had total occlusion.

CONCLUSION

In-stent restenosis was more common in open-cell stent group, which have larger free cell area than closed-cell stents. Although our radiologic findings promote us to use closed-cell design if 'possible', no difference was detected in terms of clinical outcomes.

Clinical Analysis Comparing Efficacy between a Distal Filter Protection Device and Proximal Balloon Occlusion Device during Carotid Artery Stenting

OBJECTIVE

The main concern during transfemoral carotid artery stenting (CAS) is preventing cerebral embolus dislodgement. We compared clinical outcomes and intraprocedural embolization rates of CAS using a distal filter protection device or proximal balloon occlusion device.

METHODS

From January 2011 to March 2015, a series of 58 patients with symptomatic or asymptomatic internal carotid artery stenosis ≥70% were treated with CAS with embolic protection device in single center. All patients underwent post-CAS diffusion-weighted magnetic resonance imaging (DW-MRI) to detect new ischemic lesions. We compared clinical outcomes and postprocedural embolization rates.

RESULTS

CAS was performed in all 61 patients. Distal filter protection success rate was 96.6% (28/29), whose mean age was 70.9 years, and mean stenosis was 81%. Their preprocedural infarction rate was 39% (11/28). Subsequent DW-MRI revealed 96 new ischemic lesions in 71% (20/28) patients. In contrast, the proximal balloon occlusion device success rate was 93.8% (30/32), whose mean age was 68.8 years and mean stenosis was 86%. Preprocedure infarction rate was 47% (14/30). DW-MRI revealed 45 new ischemic lesions in 57% (17/30) patients. Compared with distal filter protection device, proximal balloon occlusion device resulted in fewer ischemic lesions per patient (p=0.028). In each group, type of stent during CAS had no significant effect on number of periprocedural embolisms. Only 2 neurologic events occurred in the successfully treated patients (one from each group).

CONCLUSION

Transfemoral CAS with proximal balloon occlusion device achieves good results. Compared with distal filter protection, proximal balloon occlusion might be more effective in reducing cerebral embolism during CAS.

An Efficient Finite Element Framework to Assess Flexibility Performances of SMA Self-Expandable Carotid Artery Stents

Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at developing a computational framework based on linear and higher order FEA to evaluate the flexibility of self-expandable carotid artery stents. In particular, numerical simulations involving large deformations and inelastic shape memory alloy constitutive modeling are performed, and the results suggest that the employment of higher order FEA allows accurately representing the computational domain and getting a better approximation of the solution with a widely-reduced number of degrees of freedom with respect to linear FEA. Moreover, when buckling phenomena occur, higher order FEA presents a superior capability of reproducing the nonlinear local effects related to buckling phenomena.

Radial force measurement of endovascular stents: Influence of stent design and diameter

Background and purpose

Angioplasty and endovascular stent placement is used in case to rescue the coverage of main branches to supply blood to brain from aortic arch in thoracic endovascular aortic repair. This study assessed mechanical properties, especially differences in radial force, of different endovascular and thoracic stents.

Material and methods

We analyzed the radial force of three stent models (Epic™, E-Luminexx® and SMART®) stents using radial force-tester method in single or overlapping conditions. We also analyzed radial force in three thoracic stents using Mylar® film testing method: conformable Gore®-TAG®, Relay®, and Valiant® Thoracic Stent Graft.

Results

Overlapping SMART stents had greater radial force than overlapping Epic or Luminexx stents ( P < 0.01). The radial force of the thoracic stents was greater than that of all three endovascular stents ( P < 0.01).

Conclusions

Differences in radial force depend on types of stents, site of deployment, and layer characteristics. In clinical settings, an understanding of the mechanical characteristics, including radial force, is important in choosing a stent for each patient.

Carotid endarterectomy versus stenting: Does the flow really change? An Echo-Color-Doppler analysis

To assess potential hemodynamic differences after carotid endarterectomy (CEA) and carotid artery stenting (CAS) and their eventual impact on clinical management. Between July 2012 and October 2013 two groups of 30 patients each referred for CEA or CAS were prospectively enrolled in two tertiary hospital care centers. Pre-procedural imaging assessment of carotid artery disease was performed with Echo-Color-Doppler (ECD) and computed tomography angiography (CTA). ECD was repeated within 24 h and 1, 6 and 12 months after surgical/endovascular procedures. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at two standard sites: common carotid artery (CCA) and distal internal carotid artery (ICA). Twenty-four hours ECD findings highly differ between the two populations. CCA PSV in the CEA and CAS groups was respectively 44.88 ± 9.16 and 69.20 ± 20.04 cm/s (p = 0.002); CCA EDV was 16.11 ± 2.29 and 19.13 ± 6.42 cm/s (p = 0.065); ICA PSV was 46.11 ± 7.9 and 94.02 ± 57.7 cm/s (p = 0.0012); ICA EDV was 20.22 ± 4.33 and 30.47 ± 18.33 cm/s (p = 0.025). One month, 6 months and 1 year findings confirmed the different trend in the two cohorts; in particular, at 1 year: CCA PSV was 50.94 ± 12.44 and 60.59 ± 26.84 cm/s (p = 0.181); CCA EDV was 17.11 ± 3.46 and 19 ± 16.35 cm/s (p = 0.634); ICA PSV was 51.66 ± 10.1 and 70.86 ± 20.64 cm/s (p = 0.014); ICA EDV was 25.05 ± 8.65 and 32.66 ± 13 cm/s (p = 0.0609). ECD follow-up of patients undergone CEA or CAS may play a critical role in the clinical management. Strict surveillance of blood flow velocities allows reducing false positive re-stenosis diagnosis and choosing the best anti-aggregation therapies. Within the first month CEA patients benefit from a lower risk condition in comparison with CAS patients, due to a significantly faster PSV drop; moreover, long-term CCA PSV after CEA could be used as a surrogate marker of neointima formation.

Role of Stent Selection in the Incidence of Persisting Hemodynamic Depression After Carotid Artery Stenting

Purpose: To investigate the possible role of stent selection and procedure-related vessel diameter changes in the development of persisting hemodynamic depression (PHD) and to demonstrate the effectiveness and safety of permanent pacemaker implantation in patients with refractory PHD. Methods: Data from 584 procedures performed in 542 patients (398 men; mean age 67.3 years) between 2008 and 2011 using Wallstent, Precise, and Xact stents in a nonrandomized fashion were analyzed retrospectively. Cardiovascular risk factors and lesion, stent, and balloon characteristics were collected, and the pre- and postprocedure diameters of the common carotid artery (CCA) and internal carotid artery were measured. PHD was defined as any episode of hypotension (systolic blood pressure <90 mm Hg) and/or bradycardia (heart rate <60/min) lasting >6 hours. Risk factors for PHD were sought using logistic regression analyses; the results are presented as the odds ratio (OR) and 95% confidence interval (CI). Results: The incidence of PHD was 37.0% (216/584). Refractory PHD was encountered in 9 patients; among these, 6 were successfully treated with pacemaker implantation. A history of prior ipsilateral carotid endarterectomy (OR 0.44, 95% CI 0.22 to 0.87, p=0.019) and the presence of a contralateral high-grade stenosis (OR 0.12, 95% CI 0.02 to 0.95, p=0.045) were independent protective factors, while calcification (OR 1.5, 95% CI 1.03 to 2.18, p=0.034), involvement of the carotid bulb (OR 2.56, 95% 1.62 to 4.03, p<0.001), and implantation of a nitinol stent (adjusted OR 1.62, 95% CI 1.12 to 2.34, p=0.011) were independent risk factors for developing PHD after carotid artery stenting. The ratio of the post-/preprocedure CCA diameter (p=0.002), the stent to CCA diameter ratio (p=0.009), and the presence of residual stenosis (p=0.009) were significantly higher in the PHD group. Conclusion: Stent selection and procedure-related changes in vessel diameter may have an influence on the development of PHD. Permanent pacemaker implantation is an effective treatment option in patients with refractory PHD.

Feasibility of a Priori Numerical Assessment of Plaque Scaffolding after Carotid Artery Stenting in Clinical Routine: Proof of Concept

Purpose

Carotid artery stenting (CAS) is an alternative procedure for the treatment of severely stenosed carotid artery lesions in high-risk patients. Appropriate patient selection and stent design are paramount to achieve a low stroke and death rate in these complex high-risk procedures. This study introduces and evaluates a novel virtual, patient-specific, pre-operative environment to quantify scaffolding parameters based on routine imaging techniques.

Methods

Two patients who underwent CAS with two different sizes of the Acculink stent (Abbott Vascular, Santa Clara, CA, USA) were studied. Pre-operative data were used to build the numerical models for the virtual procedure. Numerical results were validated with post-operative angiography. Using novel virtual geometrical tools, incomplete stent apposition, free cell area and largest fitting sphere in the stent cell were evaluated in situ as quantitative measures of successful stent placement and to assess potential risk factors for CAS complications.

Results

A quantitative validation of the numerical outcome with post-operative images noted differences in lumen diameter of 5.31 ± 8.05% and 4.12 ± 9.84%, demonstrating the reliability of the proposed methodology. The quantitative measurements of the scaffolding parameters on the virtually deployed stent geometry highlight the variability of the device behavior in relation to the target lesion. The free cell area depends on the target diameter and oversizing, while the largest fitting spheres and apposition values are influenced by the local concavity and convexity of the vessel.

Conclusions

The proposed virtual environment may be an additional tool for endovascular specialists especially in complex anatomical cases where stent design and positioning may have a higher impact on procedural success and outcome.

Lesion-Related Carotid Angioplasty and Stenting with Closed-Cell Design without Embolic Protection Devices in High-Risk Elderly Patients-Can This Concept Work Out? A Single Center Experience Focusing on Stent Design

To compare the performance differences of three carotid artery stents in high-risk elderly patients without embolic protection devices (EPDs) on the basis of stent design, procedure-related complications, conveniences in handling, in-stent restenosis, 30-day outcome, and long-term follow-up. A total of 101 symptomatic internal carotid stenoses of 94 patients were prospectively treated with stent-protected angioplasty to 94 patients. Three closed-cell stents, one of those being hybrid cell design, were chosen depending on vascular anatomy: curved vessel, lesion length > 1 cm: 64 Carotid Wallstent (Boston Scientific, Natick, MA); curved vessel, lesion length < 1 cm: 21 Cristallo Ideale (Invatec, Roncadelle, Italy); straight vessel, lesion length > 1 cm: 16 Xact (Vascular Abbott, Santa Clara, CA). Comparisons of demographics, procedures, and outcomes were performed. The mean age of patients was 73.1 years (standard deviation [SD], ± 7.9; range, 58-87 years), 71% of the patients were older than 70 years and 20% were octogenarians. Male/female ratio was 3.1:1. About 13.9% (14/101) had contralateral internal carotid artery occlusion. Overall peri-interventional complication rate was 2.9% and 30-day mortality rate was 1%. During the long-term follow-up (34 months, range 1-59) no ipsilateral stroke was documented. Ten deaths (three after MI) were recognized. Two in-stent restenosis were detected (> 70% North American Symptomatic Carotid Endarterectomy Trial) during follow-up, one patient was detected with previous carotid endarterectomy. Especially, if individual anatomical variance is considered, lesion-related stent-protected carotid angioplasty with lesion-adapted closed-cell design is an effective, reliable, safe, and comprehensible treatment option in symptomatic patients. Even without EPDs, the rate of complications is low, when compared with symptomatic carotid artery stenosis described in the literature. In-stent restenosis seems to play no significant role in follow-up.

A manual carotid compression technique to overcome difficult filter protection device retrieval during carotid artery stenting

BACKGROUND

We investigated the incidence of embolic protection device retrieval difficulties at carotid artery stenting (CAS) with a closed-cell stent and demonstrated the usefulness of a manual carotid compression assist technique.

METHODS

Between July 2010 and October 2013, we performed 156 CAS procedures using self-expandable closed-cell stents. All procedures were performed with the aid of a filter design embolic protection device. We used FilterWire EZ in 118 procedures and SpiderFX in 38 procedures. The embolic protection device was usually retrieved by the accessory retrieval sheath after CAS. We applied a manual carotid compression technique when it was difficult to navigate the retrieval sheath through the deployed stent. We compared clinical outcomes in patients where simple retrieval was possible with patients where the manual carotid compression assisted technique was used for retrieval.

RESULTS

Among the 156 CAS procedures, we encountered 12 (7.7%) where embolic protection device retrieval was hampered at the proximal stent terminus. Our manual carotid compression technique overcame this difficulty without eliciting neurologic events, artery dissection, or stent deformity.

CONCLUSIONS

In patients undergoing closed-cell stent placement, embolic protection device retrieval difficulties may be encountered at the proximal stent terminus. Manual carotid compression assisted retrieval is an easy, readily available solution to overcome these difficulties.

Stent recanalization of carotid tonsillar loop dissection using the Enterprise vascular reconstruction device

Although advances in endovascular techniques have permitted reconstruction of intimal dissections and related pseudoaneurysms of the extracranial cervical internal carotid artery, highly tortuous tonsillar loop anatomic variants still pose an obstacle to conventional extracranial self-expanding carotid stents. During a 12 year period, nine of 48 cases with cervical carotid dissections were associated with a tonsillar loop. Five patients required endovascular treatment, which was performed using a microcatheter-based technique with the low-profile Enterprise vascular reconstruction device (Codman Neurovascular, Raynham, MA, USA). Technical, radiographic, and clinical outcomes were analyzed for each patient. Dissection etiology was spontaneous in three patients, iatrogenic in one, and traumatic in one. Four near-occlusive tonsillar loop dissections were successfully recanalized during the acute phase. Dissection-related stenosis improved from 90±22% to 31±13%, with tandem stents needed in three instances to seal the inflow zone. There were no procedure-related transient ischemic attacks (TIA), minor/major strokes, or deaths. Angiographic follow-up for a mean of 28.0±21.6 months showed all stents were patent, with average stenosis of 25.2±12.2%. Focal ovalization and kinking of the closed-cell design was noted at the sharpest curve in one patient. Clinical outcome (follow-up of 28.1±21.5 months) demonstrated overall improvement with no clinical worsening, new TIA, or stroke. Tonsillar loop-associated carotid dissections can be successfully and durably recanalized using the low-profile Enterprise stent with an excellent long-term patency rate and low procedural risk. The possibility of stent kinking and low radial force should be considered when planning reconstruction with this device.

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.

Incidence of embolism associated with carotid artery stenting: open-cell versus closed-cell stents

Object

Carotid artery stenting (CAS) can be an alternative option for carotid endarterectomy in the prevention of ischemic stroke caused by carotid artery stenosis. The purpose of this study was to evaluate the influence of stent design on the incidence of procedural and postprocedural embolism associated with CAS treatment.

Methods

Ninety-six symptomatic and asymptomatic patients, consisting of 79 males and 17 females, with moderate to severe carotid artery stenosis and a mean age of 69.0 years were treated with CAS. The stent type (48 closed-cell and 48 open-cell stents) was randomly allocated before the procedure. Imaging, procedural, and clinical outcomes were assessed and compared. The symptomatic subgroup (76 patients) was also analyzed to determine the influence of stent design on outcome.

Results

New lesions on postprocedural diffusion-weighted imaging (DWI) were significantly more frequent in the open-cell than in the closed-cell stent group (24 vs 12, respectively; p = 0.020). The 30-day clinical outcome was not different between the 2 stent groups. In the symptomatic patient group, stent design (p = 0.017, OR 4.173) and recent smoking history (p = 0.036, OR 4.755) were strong risk factors for new lesions on postprocedural DWI.

Conclusions

Stent design may have an influence on the risk of new embolism, and selecting the appropriate stent may improve outcome.

Percutaneous biliary drainage using open cell stents for malignant biliary hilar obstruction

Objective

To evaluate the feasibility, safety and the effectiveness of the complex assembly of open cell nitinol stents for biliary hilar malignancy.

Materials and Methods

During the 10 month period between January and October 2007, 26 consecutive patients with malignant biliary hilar obstruction underwent percutaneous insertion of open cell design nitinol stents. Four types of stent placement methods were used according to the patients' ductal anatomy of the hilum. We evaluated the technical feasibility of stent placement, complications, patient survival, and the duration of stent patency.

Results

Bilobar biliary stent placement was conducted in 26 patients with malignant biliary obstruction-T (n = 9), Y (n = 7), crisscross (n = 6) and multiple intersecting types (n = 4). Primary technical success was obtained in 24 of 26 (93%) patients. The crushing of the 1st stent during insertion of the 2nd stent occurred in two cases. Major complications occurred in 2 of 26 patients (7.7%). One case of active bleeding from hepatic segmental artery and one case of sepsis after procedure occurred. Clinical success was achieved in 21 of 24 (87.5%) patients, who were followed for a mean of 141.5 days (range 25-354 days). The mean primary stent patency period was 191.8 days and the mean patient survival period was 299 days.

Conclusion

Applying an open cell stent in the biliary system is feasible, and can be effective, especially in multiple intersecting stent insertions in the hepatic hilum.