Proximal migration of a tapered open-cell stent after carotid artery stenting for restenosis following endarterectomy.

OBJECTIVES: Stent migration is an uncommon but serious complication of carotid artery stenting. Shortening and migration of closed-cell stents after carotid artery stenting has been reported, but migration of open-cell stents is extremely rare. MATERIALS AND METHODS: Herein, we report a case of proximal migration of a tapered-design open-cell stent after carotid artery stenting for restenosis following endarterectomy for radiation-induced stenosis. RESULTS: A 70-year-old man with a history of radiation therapy for tongue cancer approximately 10 years earlier was diagnosed with transient ischemic attack owing to severe stenosis of the right cervical internal carotid artery and was referred to our hospital. We performed carotid endarterectomy with a patch graft; 6 months later, restenosis was observed. Therefore, we performed carotid artery stenting with a self-expandable tapered-design open-cell stent. On the second day after the procedure, asymptomatic downward migration of the stent was detected. During the 3-year follow-up period after stent placement, no restenosis or further stent migration was observed. CONCLUSIONS: This report provides evidence that migration of implanted carotid stents can occur even with an open-cell stents. In particular, to our knowledge, there are no reports describing migration of tapered-design open-cell stents in the early postoperative period.

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.

Open-cell stent-assisted coiling for the treatment of paraclinoid aneurysms: traditional endovascular treatment is still not out of date.

PURPOSE: Before we enter the era of flow diverter stents (FDS), the standard stent-assisted coiling technique is a well-established treatment option for routine paraclinoid aneurysms. We assess the clinical safety and efficacy of stent-assisted coiling with open-cell stent in the treatment of paraclinoid aneurysms and evaluate the association between clinical factors and follow-up aneurysm occlusion. METHODS: The clinical and radiographic data of 110 consecutive patients with 122 paraclinoid aneurysms treated with open-cell stent between April 2015 and April 2019 were analyzed retrospectively at our center. We assessed the immediate and progressive occlusion rates, complications, and clinical outcome. Multivariate analysis was performed to investigate the risk factors of angiographic incomplete occlusion. RESULTS: Among 110 patients, stent-assisted coiling was successfully performed in all cases. Four (3.6%) thromboembolic events were reported during the procedure, which resulted in transient morbidity. Immediate angiography demonstrated complete occlusion in 64 (52.5%) aneurysms and no occlusion of ophthalmic artery. Angiographic follow-up at 6 months demonstrated an increase in the complete occlusion rate to 92.9%. No delayed in-stent stenosis was observed, and three aneurysms recurred. Clinical follow-up was completed in 102 patients (92.7%), and favorable outcomes were achieved in 101 (99%) patients at 6 months. Multivariate analysis showed that aneurysm size (p < 0.001) was associated with incomplete aneurysm occlusion at follow-up. CONCLUSION: Stent-assisted coil embolization with open-cell stents is safe and effective for the treatment of paraclinoid aneurysms and provides progressive occlusion without significant in-stent stenosis events.

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.

Initial clinical experience with the micromesh Roadsaver carotid artery stent for the treatment of patients with symptomatic carotid artery disease.

PURPOSE: To assess the effectiveness, technical aspects, handling, and safety of the micromesh Roadsaver Carotid Artery Stent in the treatment of atherosclerotic carotid artery stenosis and tandem lesions in ischemic stroke patients. METHODS: Seven patients (5 men; mean age 75±11.4 years, range 53-86) suffering from symptomatic internal carotid artery (ICA) stenosis (mean 76% diameter reduction) were treated with the dual layer closed-cell stent without embolic protection. Postdilation was performed in 6 of 7 patients. Two patients were treated in the context of ischemic stroke and concurrent middle cerebral artery occlusion. Mean National Institutes of Health Stroke Scale score at admission was 12.8±5. RESULTS: All devices were deployed satisfactorily. One wall-adherent thromboembolus in a proximal ICA was covered with the Roadsaver stent in a tandem lesion setting. The modified Rankin Scale (mRS) declined from 3.7±0.7 to 2.4±0.8 in hospital, showing an improvement in clinical symptoms. No complications were detected during or after the procedure. The 30-day mRS was 1.7±1.1. At 6 months, ultrasound examination demonstrated patency of stents and the external carotid arteries. CONCLUSION: The Roadsaver double layer micromesh stent seems to be safe and effective in the treatment of extracranial ICA stenosis and in the context of tandem lesions in ischemic stroke. Further studies with larger populations are warranted.

First-in-man implantation of a new hybrid carotid stent to prevent periprocedural neurological events during carotid artery stenting.

PURPOSE: To report the initial clinical experience with a new hybrid stent to prevent neurological events during carotid artery stenting. CASE REPORT: A 77-year-old asymptomatic man presented with de novo high-grade stenosis (80%) of the right internal carotid artery (ICA) and occlusion of the contralateral ICA. He was referred for right ICA stenting with a 6/8-mm×40-mm Gore Carotid Stent under cerebral protection using the Gore Carotid Filter. The stent delivery system tracked well over the filter wire and deployment was precise. The result was satisfactory, with 10% residual stenosis. No neurological events occurred during 6 months of follow-up. CONCLUSION: Initial clinical experience with this new carotid hybrid stent showed satisfactory results, including ease of use, precise deployment, conformability to the wall, and protection against embolization.

Treatment Results of Carotid Artery Stenting with an Open-Cell Stent: Analysis of 734 Consecutive Cases at a Single Center.

OBJECTIVE: In carotid artery stenting (CAS) for internal carotid artery stenosis, the stent is often selected according to the plaque properties and arterial tortuosity. In our institute, an open-cell stent is used as the first-line stent regardless of the characteristics of the lesion. This study was performed to examine the outcome of CAS with an open-cell stent as the real-world results. METHODS: In total, 811 CAS procedures using open-cell stents were performed for internal carotid artery stenosis from April 2002 to December 2019. Of these patients, we excluded those with hyperacute conditions for which CAS was performed within 3 days of onset, those in whom acute mechanical thrombectomy was performed simultaneously with CAS, and those with stenosis due to arterial dissection. Thus, 734 patients were retrospectively analyzed. Perioperative and long-term outcomes and risk factors for perioperative infarction were investigated. RESULTS: The periprocedural stroke rate and mortality rate were 3.7% (27/734) and 0.4% (3/734), respectively. Low-echoic plaque was a significant risk factor for periprocedural stroke in both univariate (P < 0.03) and multivariate (odds ratio, 2.69; 95% confidence interval, 1.14-6.66; P = 0.02) analyses. Cerebral infarction and high grade restenosis were observed in 15 (2.0%) and 17 (2.3%) patients during a median 50-month follow-up. CONCLUSIONS: CAS with open-cell stents showed good results in terms of both the postoperative stroke incidence and long-term severe restenosis rate. However, low-echoic plaque was a risk factor for perioperative stroke incidence, which should be considered when deciding on the indication for CAS with an open-cell stent.

Folding Deformation of Open-Cell Stents in Carotid Artery Stenting: Report of Three Cases and Review of Literature.

Objective: We describe 3 cases with folding deformation of a PRECISE (Cordis, Miami, FL, USA) stent in carotid artery stenting (CAS). Case Presentations: The 3 cases with cervical carotid stenosis consisted of 3 males around 80 years old and included 2 symptomatic lesions. During CAS, distal embolic protection was established using a Mo.Ma (Medtronic, Minneapolis, MN, USA) along with a filter device in 2 cases and an Optimo (Tokai Medical Products, Aichi, Japan) along with a filter device in 1 case. For the filter device, either FilterWire EZ (Boston Scientific, Natick, MA, USA) or Spider FX (Covidien, Irvine, CA, USA) was employed. In all cases, a PRECISE stent was deployed after pre-dilation performed using a percutaneous transluminal angioplasty (PTA) balloon with the diameter of 2.5 to 3 mm. Post-dilation was performed after the stent deployment using a PTA balloon whose diameter was about 80% of that of the normal distal internal carotid artery. In all cases, cone-beam CT taken after the deployment of a stent showed folding deformation of the stent. In 2 cases, heavily calcified plaque hampered self-expansion of the stent, which resulted in the stent deformation. On the other hand, in the remaining 1 case, a distal shaft of the Mo.Ma caused the stent deformation, which was likely accelerated by head rotation and cervical compression that was performed to resolve difficulties for a filter retrieval device to pass through the stent, and post-dilation after the stenting. Conclusion: Heavily calcified plaque and a distal shaft of a Mo.Ma would result in stent deformation.

Prospective multicentre study of carotid artery stenting using the MER™ Stent - the OCEANUS study - 30-day and one-year follow-up results.

INTRODUCTION: Constant technological progress in the field of carotid stenting translates into improved short- and long-term results of endovascular treatment. The introduction of a new generation, self-expanding, open-cell stent has provided a new treatment option in endovascular management of carotid stenosis. AIM: To evaluate 30-day and 1-year clinical outcomes of non-consecutive patients with high risk of carotid endarterectomy, who underwent 5F cylinder-tapered MER™ open-cell carotid stent implantation. MATERIAL AND METHODS: It was a single-arm, prospective study conducted in four experienced catheterisation centres. The use of embolic protection devices was mandatory. The primary endpoint was stroke in 30-day follow-up. The secondary endpoints were 30-day and 1-year cumulative incidence of death, stroke and myocardial infarction, 1-year target vessel revascularisation, procedural success (residual stenosis ≤ 30%), restenosis rate (%DS ≥ 50%), and Serious Adverse Device Effect (SADE) rate in 1-year follow-up. RESULTS: In total 100 patients were recruited for the study, with the majority being males (n = 61). The mean age was 68.3 ±8.2 years, and most of the patients were asymptomatic (n = 56). In 55 (55%) patients direct stenting was performed, with the use of proximal protection devices in 19 (19%) patients. Mean internal carotid artery/common carotid artery stenosis before and after stent implantation was 81.98 ±9.15% and 12.52 ±8.70%, respectively (p < 0.001). Procedural success was achieved in all cases. One ischaemic stroke was observed at 30 days (1%, primary endpoint). At 1-year follow-up two myocardial infarctions and three deaths occurred with no additional stroke. CONCLUSIONS: The OCEANUS study indicated the safety and efficacy of the MER™ stent during 30-day and 1-year follow-up in both symptomatic and asymptomatic patients. The majority of patients were event-free. However, larger cohort studies are needed to evaluate MER™ stents in detail.

Passability and Impassability of Microcatheters Through the Neuroform Atlas Stent During the Trans-cell Approach: An Experimental Evaluation.

BACKGROUND: Trans-cell approach for the Neuroform Atlas stent (Stryker Neurovascular, Fremont, CA) is occasionally unsuccessful as a microcatheter can become stuck in the struts. This study aimed to evaluate the passability and impassability of 0.0165-inch microcatheters through the Neuroform Atlas stent using a simplified benchtop model. METHODS: The distal struts of the target cell, referred to as the concave or convex crown, were found to interfere with microcatheter advancement during the trans-cell approach. The procedure was performed across each crown using the 1.7-Fr SL-10 and 1.6-Fr Headway Duo microcatheters (MicroVention-Terumo, Aliso Viejo, CA), and it was repeated 20 times. We evaluated the procedural success rate, passability of each microcatheter using the maximum moving distance of the target crown in successful procedures, and device behaviors. RESULTS: The procedural success rate across the concave crown was significantly higher than that across the convex crown in both microcatheters. The maximum moving distance of the concave crown was significantly shorter in the Headway Duo microcatheter than in the SL-10 microcatheter. All procedures across the convex crown were not successful because the sharp end of the crown fell into the interspace inside the microcatheter tip, which is referred to as the crown jackpot phenomenon. The trapped microcatheter was never released from the crown unless it was pulled back proximally. CONCLUSIONS: Target crowns and microcatheters affected the use of the trans-cell approach through the Neuroform Atlas stent. The passability was excellent in a lower profile 0.0165-inch microcatheter. Moreover, neurointerventionalists must be knowledgeable of the crown jackpot phenomenon, which might cause fatal stent migration.

Coil Embolization for Cerebral Aneurysms Using a Semi-Jailing Technique and Open-Cell Stent.

BACKGROUND: Numerous reports have described the semi-jailing technique (SJT) using a closed-cell stent for stent-assisted coil embolization, revealing issues including poor expansion and thrombotic complications in curved vessels. This paper reports preliminary experience with SJT using an open-cell stent, a novel type of stent allowing stent placement from a microcatheter. METHODS: First, this research investigated differences between open- and closed-cell types in SJT using silicone vessel models. Next, 43 patients who underwent SJT for the internal carotid artery were divided into 2 groups to investigate treatment outcomes: 24 patients with placement of an open-cell stent (open-cell group) and 19 patients with closed-cell stents (closed-cell group). RESULTS: In the silicone vessel model, coils could be placed with the open-cell stent deployed with a shorter length than the closed-cell stent. No significant differences were found between groups in terms of maximum diameter of the aneurysm or dome-neck ratio. The open-cell group showed a trend toward higher complete embolization immediately after surgery (54.2% vs. 26.3%, P = 0.06), with few cases of stent malapposition (0% vs. 31.6%, P < 0.01). However, 1 case of ischemic complication in the closed-cell group and 1 case of hemorrhagic complication in open-cell group occurred. All cases of modified Rankin Scale scores at discharge were 0-1. CONCLUSIONS: Although the open-cell stent carries the disadvantage of an unresheathable design, coil placement with a shorter stent deployment length may be advantageous during SJT for internal carotid artery aneurysm embolization with favorable consequences for excellent vessel wall apposition.

Stent-assisted coiling of cerebral aneurysms with the Neuroform Atlas stent.

Objectives The Neuroform Atlas stent (AS) is the smallest intracranial stent with an open-cell design. This study reports the first clinical experience with AS. Methods All intracranial aneurysms treated by stent-assisted coiling using a single AS in a single institution were retrospectively evaluated. Patient demographics, aneurysm characteristics, angles between the parent artery and stented branch, technical success, and clinical and angiographic follow-up were analyzed. Results Fifty-five consecutive aneurysms treated with AS-assisted coiling were included. Of these, 69.1% were located distal to the circle of Willis. Technical success rate was 100%. The mean diameters of proximal and distal parent arteries were 2.62 mm (range 1.5-4.4) and 1.8 mm (range 0.8-3.5), respectively. Except for a minor stroke in a patient who completely discontinued antiplatelet therapy on postoperative day 4, there were no clinical events with permanent sequelae, and 94.1% of patients had Raymond-Roy score of 1 or 2 aneurysmal occlusion at a mean follow-up duration of 7.9 months. Although the angle between the parent artery and the stented branch increased significantly ( p < 0.001) with time, the angular change at follow-up was only 16.45 ± 11.03 degrees and was inversely correlated both with preoperative angle and the diameter of the distal parent artery ( r = -0.465 and r = -0.433, respectively, p = 0.004 for both). Conclusion AS-assisted coiling was associated with a favorable early clinical outcome and angiographic results in this series. This stent can be used for distally located aneurysms and results in minimal alteration of the arterial anatomy.

Open-cell stent and use of cone-beam CT enables a safe and effective coil embolization of true ophthalmic artery and anterior choroidal artery aneurysms with preservation of parent vessel: Clinical and angiographic results.

Background Treatment of true ophthalmic artery (OA) or anterior choroidal artery (AChA) aneurysms with preservation of the parent vessel may be challenging. Flow diverters have limitations when dealing with branch vessels arising from the aneurysm sac. Visual loss or AChA territory infarcts have been reported both for surgical and endovascular treatment. Methods We evaluated the safety and efficacy of an open-cell design, laser-cut, self-expanding Nitinol stent, and use of cone-beam computed tomography (CBCT) for stent-assisted coil embolization. Results A total of seven patients with unruptured OA or AChA aneurysms were enrolled in this prospective small case study and the data were analyzed retrospectively. A complete obliteration was achieved in all aneurysms immediately post-intervention or at six-month follow-up without any evidence for recanalization at up to three-year follow-up. All patients tolerated the procedure well and there was no change in baseline modified Rankin Scale. Conclusions Our study suggests that specific features of an open-cell stent allow a safe and effective treatment of OA or AChA aneurysms with a high technical success rate and excellent mid-term angiographic and clinical outcome. CBCT is a useful intraoperative imaging tool.

Use of self-expanding stents for better intracranial flow diverter wall apposition.

Background Flow diverter (FD) malapposition is associated with stroke-related complications. We document the use of self-expanding nitinol stents to remove/reduce the ledge of a FD deployed for aneurysm treatment. Methods We identified five patients who were treated with the Pipeline embolization device (PED) in conjunction with a Neuroform EZ stent for inadequate wall apposition of the ends of the FD at our institution between May 2014 and July 2015. Among other parameters, angiographic results, cone-beam computed tomography assessment of wall apposition and patient clinical outcome were evaluated. Results Incomplete device end apposition was seen in three cases, and precarious positioning of the distal end of the PED over the aneurysm neck was seen in two cases. In all five cases, successful treatment with good wall apposition and proper pinning of the PED distal edge was achieved using an additional Neuroform EZ stent. Appropriate aneurysm neck coverage and flow stagnation was seen in all cases. The combination of high radial outward force and open-cell design permits the Neuroform EZ stent to jail the malappositioned edges of the FD while maintaining good vessel-wall apposition itself and prevent migration of the PED. Short-term follow-up angiography showed device patency and complete aneurysm obliteration in all cases. Conclusions Preliminary results of this small case series suggest that the Neuroform EZ stent allows for effective treatment of FD malapposition in selected patients amenable for this endovascular approach. Long-term and larger cohort studies are needed to validate these results.

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.

The Interference Phenomenon of Microcatheters in the Jailing Treatment for Internal Carotid Artery Side Wall Aneurysms with an Open Cell Stent System.

OBJECTIVE: Excelsior XT-27 (Stryker Neurovascular, Fremont, CA, USA) or Rebar 27 (eV3 Covidien, Irvine, CA, USA) microcatheters have recently been used to overcome the limitations of the Renegade Hi-Flo microcatheter such as interference between two microcatheters (one for stent delivery and the other for cerebral aneurysm coiling) during the jailing technique. We evaluated differences and influential factors related to the interference phenomenon according to these two microcatheters group. MATERIALS AND METHODS: Between June 2011 and September 2013, the jailing technique was applied to 94 internal cerebral artery (ICA) aneurysms. The jailing technique with the Neuroform EZ stent system was performed using Renegade (n = 22), Rebar (n = 35), and XT-27 microcatheters (n = 37). In the Renegade Hi-Flo microcatheter group, the jailing technique was successful in 19/22 patients (86.4%) and interference between the two microcatheters occurred in 6/21 patients (28.6%). In the Rebar and XT-27 microcatheter group, the jailing technique was successful in 71/72 patients (98.6%) and interference between the two microcatheters occurred in 1/72 patients (1.4%). RESULTS: There was a significant difference in the interference between the two delivered microcatheters group (p-value < 0.000) and the carotid siphon angle (p-value: 0.004) in the univariate analysis. In the multiple logistic regression analysis, the Rebar and XT-27 microcatheter group (odds ratio [OD] [95% confidence interval (CI)]; 31.277 [3.138-311.729], p-value: 0.003) and the carotid siphon angle (OD [95%CI]; 0.959 [0.922-0.997], p-value: 0.035) were found to be influential factors in the interference phenomenon. CONCLUSION: The Rebar 27 and XT-27 microcatheters were more successful and exhibited less interference between the two microcatheters than the Renegade Hi-Flo microcatheter.