Clinical Results of Cerebral Protection with a Filter Device During Stent Implantation of the Carotid Artery

Purpose: To assess the technical feasibility and the clinical results of cerebral protection with the Angioguard emboli-capture guidewire system during carotid artery stenting (CAS) for high-grade stenoses. Methods: In 20 patients 20 stenoses of the internal carotid artery were treated with stent implantation. In all patients diffusion-weighted (DW) magnetic resonance imaging (MRI) of the brain was performed before and 24 hr after the procedure. Results: The filter device was effectively employed during all steps of the procedure in 16 of 20 patients, in two only postdilation could be protected, and in two no protection was possible. After three of the 20 procedures new ipsilateral cerebral lesions were visualized by DW-MRI. No new permanent neurologic deficits occurred. Conclusion: Cerebral protection with the filter device is technically feasible in most cases. DW-MRI demonstrated new cerebral lesions indicating the occurrence of cerebral microemboli during the protected procedures. Further investigations are necessary to determine whether the use of the cerebral protection device will improve the results of CAS.     

Flow Velocities After Carotid Artery Stenting: Impact of Stent Design. A Fluid Dynamics Study in a Carotid Artery Model with Laser Doppler Anemometry

Purpose To study the influence of a newly developed membrane stent design on flow patterns in a physiologic carotid artery model.Methods Three different stents were positioned in silicone models of the carotid artery: a stainless steel stent (Wall-stent), a nitinol stent (SelfX), and a nitinol stent with a semipermeable membrane (MembraX). To increase the contact area of the membrane with the vessel wall, another MembranX model was modified at the outflow tract. The membrane consists of a biocompatible silicone-polyurethane copolymer (Elast-Eon) with a pore size of 100 m. All stents were deployed across the bifurcation and the external carotid artery origin. Flow velocity measurements were performed with laser Doppler anemometry (LDA), using pulsatile flow conditions (Re = 220; flow 0.39 l/min; flow rate ratio ICA:ECA = 70:30) in hemodynamically relevant cross-sections. The hemodynamic changes were analyzed by comparing velocity fluctuations of corresponding flow profiles.Results The flow rate ratio ICA:ECA shifted significantly from 70/30 to 73.9/26.1 in the MembraX and remained nearly unchanged in the SelfX and Wallstent. There were no changes in the flow patterns at the inflow proximal to the stents. In the stent no relevant changes were found in the SelfX. In the Wallstent the separation zone shifted from the orifice of the ICA to the distal end of the stent. Four millimeters distal to the SelfX and the Wallstent the flow profile returned to normal. In the MembraX an increase in the central slipstreams was found with creation of a flow separation distal to the stent. With a modification of the membrane this flow separation vanished. In the ECA flow disturbances were seen at the inner wall distal to the stent struts in the SelfX and the Wallstent. With the MembraX a calming of flow could be observed in the ECA with a slight loss of flow volume.Conclusions Stent placement across the carotid artery bifurcation induces alterations of the physiologic flow behavior. Depending on the stent design the flow alterations are located in different regions. All the stents tested were suitable for the carotid bifurcation. The MembraX prototype has shown promising hemodynamic properties ex vivo.     

血管内支架治疗颈动脉及椎动脉狭窄的20例临床分析

目的探讨血管内支架治疗颈动脉及椎动脉狭窄的安全性及有效性。资料与方法对20例颈、椎动脉狭窄行颈动脉球囊扩张及支架成形术(CAS)治疗的患者作回顾性分析,对临床表现、治疗方法及治疗前后的影像资料改变进行分析。结果 20例患者行CAS治疗,共成功放置支架22枚,11例采用颈动脉保护装置。术前干预血管平均狭窄度(76.2±11.4)%,术后支架膨胀不满意采用球囊后扩者3例。术后造影显示15例残余狭窄度<10%,4例<20%,仅1例<38%,术后平均狭窄度(12.4±8.2)%。治疗前后狭窄度比较有显著统计学意义(P<0.001)。随访平均(12.3±5.6)个月,7例支架术后6个月发现支架有不同程度再狭窄,但再狭窄率均未超过30%,均无神经系统症状。结论血管内支架治疗颈动脉及椎动脉狭窄是安全和有效的,近期随访无严重再狭窄(>50%)及颅内严重并发症发生。     

Treatment of Internal Carotid Artery Dissections with Endovascular Stent Placement: Report of Two Cases

Extracranial carotid artery dissection may manifest as arterial stenosis or occlusion, or as dissecting aneurysm formation. Anticoagulation and/or antiplatelet therapy is the first-line treatment, but because it is effective and less invasive than other procedures, endovascular treatment of carotid artery dissection has recently attracted interest. We encountered two consecutive cases of trauma-related extracranial internal carotid artery dissection, one in the suprabulbar portion and one in the subpetrosal portion. We managed the patient with suprabulbar dissection using a self-expandable metallic stent and managed the patient with subpetrosal dissection using a balloon-expandable metallic stent. In both patients the dissecting aneurysm disappeared, and at follow-up improved luminal patency was observed.     

In Vitro Evaluation of the Effectiveness of Distal Protection in the Prevention of Cerebral Thromboembolism During Carotid Stent Placement

RATIONALE AND OBJECTIVES: The purpose of this in vitro study was to evaluate and quantify the benefit of the balloon protection device, to identify the most effective sequence of irrigation or flushing, and to determine the most effective catheter position to remove the maximum number of emboli or debris beneath the flow-arrest balloon. MATERIALS AND METHODS: Silicone models of the neurovasculature were attached to a systodiastolic pump. Stents were placed in carotid stenoses by using the distal flow protection technique. Embolic material was released within the stent. The effectiveness of different irrigation techniques was evaluated. RESULTS: Aspiration under the balloon through the guiding catheter with a 60-mL syringe followed by one power injection at 40 mL injected at 2 mL/sec will result in removal of about 98% of potential emboli from the internal carotid artery [corrected]. CONCLUSION: In vitro evaluation of the distal flow protection technique indicates that it should reduce stroke risk during carotid stent placement.     

脑供血动脉狭窄支架术前后脑CT灌注评价

目的:探讨症状性脑供血动脉狭窄内支架成形术前术后脑CT灌注成像的各项参数变化及其与临床症状转归的相关性.方法:本研究纳入10例患者,全部经全脑DSA证实有单侧脑供血动脉狭窄(≥65%),所有患者于血管内支架术前及术后48h内行脑CT灌注成像检查,测量CBV、CBF、TTP并同时予以NIHSS评分.结果:10例患者行脑供血动脉狭窄内支架成形术前术后48h内的大脑中动脉供血区域的脑CT灌注成像的各项参数变化如下:9例患者术后的rTTP较术前明显缩短,1例患者rTTP术后与术前相同(P=0.01<0.05);5例患者术后的rCBV及rCBF较术前均升高,另外有4例患者术后的rCBV及rCBF较术前均降低,1例患者术后的rCBV较术前降低rCBF较术前升高.7例患者术后NIHSS评分降低(P=0.004<0.05).症状性脑供血动脉狭窄内支架成形术前术后脑CT灌注成像参数变化及其与临床症状转归相关系数r=-0.062,P=0.864>0.05.结论:脑CT灌注成像是评估症状性脑供血动脉狭窄内支架成形术后脑灌注改善的可信指标.CTP参数变化与临床症状转归没有相关性.     

Medical Therapy for Asymptomatic Patients and Stent Placement for Symptomatic Patients Presenting with Carotid Artery Near-Occlusion with Full Collapse

Purpose

To report long-term results of stent placement and medical therapy for symptomatic and asymptomatic patients, respectively, with carotid artery near-occlusion with full collapse.

Pseudoaneurysm of the Internal Carotid Artery: Treatment with a Covered Stent

Dissection of the cervical segment of the internal carotid artery may occur spontaneously or after trauma. We report the management of a 53-year-old right-handed man with progressive dizziness and neck pain 6 weeks after a motor vehicle collision. The clinical and neurologic examinations were normal. The CT scan led to the diagnosis of a pseudoaneurysm of the right internal carotid artery near the skull base. We successfully treated this post-traumatic lesion with a covered stent. The patient underwent the endovascular procedure under general anesthesia and transcranial Doppler monitoring. No neurologic event was observed. Obliteration of the pseudoaneurysm with preservation of the carotid artery was achieved. The patient was discharged from the hospital 72 hr later with no complications. Clinical and imaging follow-up at 6 months was unremarkable.     

超声二维应变成像评价脑梗死患者颈动脉弹性功能

目的 应用超声二维斑点追踪成像(speckle tracking imaging,STI)评价脑梗死患者颈动脉弹性的变化.资料与方法 应用STI技术检测60例脑梗死患者颈动脉弹性功能改变,并与55例正常人相对照.结果 ①脑梗死患者CS和CSR均小于对照组,β1、β2均较对照组升高,各组间差异有统计学意义.②β1和β2显...     

Quantification of Internal Carotid Artery Flow with Digital Subtraction Angiography: Validation of an Optical Flow Approach with Doppler Ultrasound

BACKGROUND AND PURPOSE:Digital subtraction angiography is the reference standard technique to evaluate intracranial vascular anatomy and used on the endovascular treatment of vascular diseases. A dedicated optical flow-based algorithm was applied to DSA to measure arterial flow. The first quantification results of internal carotid artery flow validated with Doppler sonography are reported.MATERIALS and METHODS:We included 22 consecutive patients who underwent endovascular procedures. To assess the sensitivity of the algorithm to contrast agent-blood mixing dynamics, we acquired high-frame DSA series (60 images/s) with different injection rates: 1.5 mL/s (n = 19), 2.0 mL/s (n = 18), and 3.0 mL/s (n = 13). 3D rotational angiography was used to extract the centerline of the vessel and the arterial section necessary for volume flow calculation. Optical flow was used to measure flow velocities in straight parts of the ICAs; these data were further compared with Doppler sonography data. DSA mean flow rates were linearly regressed on Doppler sonography measurements, and regression slope coefficient bias from value 1 was analyzed within the 95% confidence interval.RESULTS:DSA mean flow rates measured with the optical flow approach significantly matched Doppler sonography measurements (slope regression coefficient, b = 0.83 ± 0.19, P = .05) for injection rate = 2.0 mL/s and circulating volumetric blood flow <6 mL/s. For injection rate = 1.5 mL/s, volumetric blood flow <3 mL/s correlated well with Doppler sonography (b = 0.67 ± 0.33, P = .05). Injection rate = 3.0 mL/s failed to provide DSA–optical flow measurements correlating with Doppler sonography because of the lack of measurable pulsatility.CONCLUSIONS:A new model-free optical flow technique was tested reliably on the ICA. DSA-based blood flow velocity measurements were essentially validated with Doppler sonography whenever the conditions of measurable pulsatility were achieved (injection rates = 1.5 and 2.0 mL/s).

Even though digital subtraction angiography has traditionally been confined to standard anatomy assessment, quantification of blood flow based on DSA is becoming an important topic that could help neurointerventionists in making adequate peri-procedural decisions. Some reports have described new techniques based on DSA that are able to assess flow or flow changes during treatment of stented aneurysms.^1,2 However, the development of clinically useful tools based on the integration of engineering, hemodynamic and physiologic knowledge still requires improved translation of biofluid mechanical information into clinical applications.³ X-ray video densitometry, based on the detection of the displacement of radiopaque contrast material through the vascular system, has been studied since the early 1960s and has been divided into 2 main classes: tracking and computational methods.⁴ Sarry et al⁵ estimated the flow by using an inverse advection model. Bogunović and Loncarić⁶ proposed the combination of DSA and 3D rotational angiography (3DRA), using an analysis of the time-attenuation curves. Rhode et al⁷ developed a model-based and weighted-optical field (OF) approach to improve already existing techniques and compared the results with simulation data, while Imbed et al^8,9 developed a similar approach on the femoral artery and simulated angiographic data. Waechter et al¹⁰ developed a model-based approach to measure flow in the cerebral arteries.These approaches were all limited in case of fast flows, required longer straight-vessel segments, and were affected by low signal-to-noise ratios. A dedicated algorithmic scheme was developed to reduce instabilities due to temporal and spatial noise and to cope with fast flows, to address these issues.¹¹ Essentially, we used only the modulation by the cardiac cycle to extract flow-velocity values. The OF principle was then applied to the pulsating component of dye-concentration signal.¹¹ In this article, the first clinical results of the proposed algorithm applied to the ICA are reported. The clinical implementation and verification against Doppler ultrasound (USD) data in a consecutive cohort of patients are described, and the limits of the current technique are discussed.     

Stent Fracture and Reocclusion After Placement of a Single Self-Expanding Stent in the Common Iliac Artery and Endovascular Treatment

We present a case of fracture of a single self-expanding stent placed in the common iliac artery (CIA). An 80-year-old woman underwent placement of a self-expanding stent for CIA occlusion. Stent fracture and reocclusion were detected after 18 months. Successful revascularization was achieved using a stent-in-stent maneuver. The possibility of stent fracture with reocclusion should be considered following treatment with a single self-expanding stent for CIA occlusion.     

Usefulness of Grasping a Guiding Catheter with a Loop-Snare Wire for Stent Placement into the Vertebrobasilar Artery

In cases in which the subclavian artery is severely tortuous or branches with an extremely angulated origin, stent placement in the vertebrobasilar artery on the approach from the femoral artery is often technically difficult. We report two cases in which a stent placement procedure for the vertebrobasilar artery was successfully performed by grasping a guiding catheter with a loop-snare wire. This technique is useful for tortuous arteries or arteries branching with an extremely angulated origin.     

Cerebral Ischemia Detected with Diffusion-Weighted MR Imaging after Protected Carotid Artery Stenting: Comparison of Distal Balloon and Filter Device

Objective

The aim of this study was to examine the incidence of ischemia during protected carotid artery stenting (CAS) as well as to compare the protective efficacy of the balloon and filter devices on diffusion-weighted MR imaging (DWI).

Materials and Methods

Seventy-one consecutive protected CAS procedures in 70 patients with a severe (> 70%) or symptomatic moderate (> 50%) carotid artery stenosis were examined. A balloon device (PercuSurge GuardWire) and a filter device (FilterWire EX/EZ, Emboshield) was used in 33 cases (CAS-B group) and 38 cases (CAS-F group) to prevent distal embolization, respectively. All the patients underwent DWI within seven days before and after the procedures. The number of new cerebral ischemic lesions on the post-procedural DWI were counted and divided into ipsilateral and contralateral lesions according to the relationship with the stenting side.

Results

New cerebral ischemic lesions were detected in 13 (39.4%) out of the 33 CAS-Bs and in 15 (39.5%) out of the 38 CAS-Fs. The mean number of total, ipsilateral and contralateral new cerebral ischemic lesion was 2.39, 1.67 and 0.73 in the CAS-B group and 2.11, 1.32 and 0.79 in the CAS-F group, respectively. No statistical differences were found between the two groups (p = 0.96, 0.74 and 0.65, respectively). The embolic complications encountered included two retinal infarctions and one hemiparesis in the CAS-B group (9.09%), and one retinal infarction, one hemiparesis and one ataxia in the CAS-F group (7.89%). There was a similar incidence of embolic complications in the two groups (p = 1.00).

Conclusion

The type of distal protection device used such as a balloon and filter does not affect the incidence of cerebral embolization after protected CAS.     

颈动脉16层螺旋CT成像和应用

随着多层螺旋CT的不断发展,多层螺旋CT成像及血管造影已成为颈动脉疾病的主要检查方法,研究证明CTA在评价颈动脉的狭窄和闭塞上与DSA有高度的一致性,可常规用来评价颈动脉狭窄等病变.同时CTA还可用来评价颈部血管外伤,可以发现颈部血管部分或完全闭塞、假性动脉瘤、夹层、动静脉瘘等,以及颈部软组织、气道、颈髓椎管等部位的病变,可作为怀疑颈部血管外伤但暂无手术指征的无创性检查方法.     

颈内动脉狭窄时侧支循环与脑梗死关系的研究

目的 探讨颈内动脉狭窄时各侧支循环途径出现的概率及与脑梗死的关系.资料与方法 将脑血管造影(DSA)发现颈内动脉狭窄>70%的43例患者作为研究对象,并将其中23例脑梗塞患者作为症状组;20例无脑梗死患者作为无症状组.观察侧支循环的组成、Willis环是否变异及其组成血管的管径,分析侧支循环与脑梗死的关系.结果 Willis环代偿是主要的侧支循环,症状组前、后环的变异率大于无症状组,症状组前交通动脉的管径为(1.2540±0.1438)mm,小于无症状组(1.4306±0.2199)mm(P=0.006).结论 颈内动脉狭窄患者是否出现缺血性症状与Willis环的代偿能力相关,Willis环的代偿潜能与Willis环是否存在变异及前交通动脉、后交通动脉的管径有关.