A novel flexible, retrievable endovascular stent system for small-vessel anatomy: preliminary in vivo data

BACKGROUND AND PURPOSE: This study assessed the in vivo delivery, retrievability, short-term patency, and cellular response to a new flexible endovascular stent system in a rabbit model. The stent is designed for delivery through a microcatheter and is fully retrievable with electrolytic detachment from a delivery wire. METHODS: We successfully deployed nine stents (range of sizes, 2.5-4 mm diameter, 15-35 mm length) in six straight (carotid) and three angled (subclavian) arteries of six Chinchilla Bastard rabbits. Serial imaging was performed by using intravenous digital subtraction angiography (IVDSA), contrast-enhanced MR angiography (CEMRA), time-of-flight MR angiography (TOF), and CT-angiography 3 days and 4 weeks after stent deployment. Subjects were euthenized after 4 weeks (n = 5), and stents were removed for histologic analysis. RESULTS: Stent deployment was feasible in all cases. After initial deployment, all stents could be fully retrieved within the microcatheter. The detachment zone and the distal stent marker were easily visible under fluoroscopy, and final detachment occurred reliably in all cases. We observed no procedural complications. Noninvasive imaging by using IVDSA, MR angiography, and CT angiography was feasible in this stent system and demonstrated all arteries patent and not narrowed at 3 days and 4 weeks, findings that were confirmed by histologic analysis. CONCLUSION: This electrolytically detachable stent is promising as a treatment for intracranial arteries, because it can be delivered through microcatheters small enough for intracranial navigation. It is fully retrievable, thus providing greater control than currently available stents. Noninvasive imaging by using IVDSA, MR angiography, and CT angiography is feasible in this stent system and may be useful for follow-up. Further long-term data are needed.     

血管内支架治疗颅内动脉瘤

目的：探索使用血管内支架及血管内支架结合电解可脱卸弹簧圈（Guglielmi detachable coil,GDC)治疗颅内梭形及宽颈动脉瘤的可能性。方法：3例椎动脉颅内段梭形动脉瘤及6例宽颈动脉瘤,首先将冠脉支架跨动脉瘤颈放置,通过支架的网孔将微导管送入动脉瘤腔,填入GDC。结果：7例动脉瘤致密堵塞,2例大部堵塞,载瘤动脉通畅,临床效果优良。结论：联合使用支架及微弹簧圈是治疗颅内梭形及宽颈动脉瘤可选择的有效方法之一。     

Neuroform颅内支架辅助栓塞宽颈颅内动脉瘤的初步经验

目的　报道我科使用Neuroform支架辅助可脱式弹簧圈栓塞宽颈脑动脉瘤的初步经验。方法　 2 2例 2 4枚宽颈颅内动脉瘤采用Neuroform支架和弹簧圈进行栓塞 ,其中急性破裂动脉瘤 19枚、未破裂动脉瘤 5枚。结果　支架均成功地释放 ,支架置入后的造影未发现有瘤内造影剂滞留的血流动力学改变。 10 0 %闭塞动脉瘤 18枚 ,90 %以上闭塞 5枚 ,1枚伴发的未破裂小型宽颈动脉瘤在支架置入后微导管无法超选 ,载瘤动脉均通畅。有 2枚动脉瘤虽有支架阻挡 ,但仍有部分弹簧圈畔进入载瘤动脉。所有患者没有出现与支架置入有关的症状性缺血性并发症。 17例造影随访中 ,有 1例在 3个月复查时发现再通 ,进行 2次栓塞完全闭塞动脉瘤 ,其余未见复发 ,结论　Neuroform颅内支架使用安全有效 ,适合于宽颈颅内动脉瘤的支架辅助弹簧圈栓塞 ,特别适合于迂曲的脑血管 ;其径向支撑力较差 ,在输送微导管时应防止其移位 ;其支架网眼较大 ,对血流动力学改变不明显 ,致密填塞是重要的 ,在输送弹簧圈时仍应防止弹簧圈畔进入载瘤动脉 ;术前、术后抗血小板药物的应用以及术后严格的系列造影随访是必要的。     

Study of the patency of small arterial branches after stent placement with an experimental in vivo model

BACKGROUND AND PURPOSE: The patency of intracranial perforating arteries after stent placement is unknown despite the general clinical use of intracranial arterial stenting. METHODS: We deployed stainless steel stents in the abdominal aorta across the lumbar artery in eight normal rabbits in which the diameters of the abdominal arterial vessels were similar to those of human intracranial arteries. We evaluated the patency via angiographic and scanning electron microscopic methods 3 months after stent placement. Histopathologic evaluation was also performed for one rabbit. RESULTS: The lumbar arteries were patent, even when stent struts crossed the ostium, except in one rabbit in which intimal dissection occurred intraoperatively. The scanning electron microscopy showed that the regenerative endothelium had grown onto the strut at the ostium of the lumbar artery. CONCLUSION: We confirmed the patency of the lumbar arteries in this study by using normal rabbits. Thus, intracranial stenting may not pose a risk of occluding perforating arteries of the same diameter of the lumbar artery, even if stent struts cover the ostium.     

血管内支架结合弹簧圈治疗颅内宽颈动脉瘤的临床研究

目的 探讨血管内支架结合电解可脱卸弹簧圈(GDC)治疗颅内宽颈动脉瘤的适应证、技术要点、并发症防治及疗效，评估该技术的安全性及疗效。方法 105例颅内宽颈动脉瘤(前循环78例，后循环27例)，首先将冠脉支架跨动脉瘤颈放置，通过支架上的网孔将微导管送入动脉瘤腔，填塞GDC，术后3、6、12个月随访临床症状，6～12个月脑血管造影随访。结果 104例手术成功，1例失败；80例动脉瘤达到致密填塞，24例大部填塞，载瘤动脉通畅；1例术中发生脑梗死，1例发生颈动脉夹层动脉瘤，1例术中动脉瘤破裂，1例在GDC填塞过程中支架完全塌陷。98例临床随访3～32个月，均无再出血或血栓栓塞的症状。血管造影随访62例(随访期6～12个月)，60例动脉瘤不再显影，2例明显缩小，1例出现支架近端轻度狭窄。结论 联合使用支架和微弹簧圈是治疗颅内宽颈动脉瘤安全有效的方法，支架使宽颈动脉瘤的介入治疗成为可能，支架不但可防止弹簧圈突入载瘤动脉，还可防止弹簧圈压缩，促进瘤内血栓形成，防止动脉瘤复发，长期疗效有待于进一步观察。     

Self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty

The feasibility of self-expanding nitinol stents for treatment of infragenicular arteries following unsuccessful balloon angioplasty was assessed. Options for lower limb percutaneous revascularization are limited, especially for complex vessel obstruction. Depending on the lesion and the experience of the interventionalist, the failure rate of balloon angioplasty (PTA) ranges between 10 and 40%. Until recently, no self-expanding stent for the use in the infragenicular arteries was available. This is the first report of the results for 18 consecutive patients who received 4F sheath compatible self-expanding nitinol stents following unsuccessful PTA or early restenosis. Twenty-four stents were implanted in 21 lesions for various indications residual stenosis >50% due to heavy calcification, flow-limiting dissection, occluding thrombus resistant to thrombolyis, thrombaspiration, and PTA, and early restenosis after previous PTA. Stent implantation was feasible in all cases. No complications occurred. After the stent implantation, all primarily unsuccessful interventions could be transformed into successful procedures with no residual stenosis >30% in any case. After 6 ± 2 months, two of the 18 patients died, and 14 of the 16 remaining patients improved clinically. At follow-up, the patency could be assessed in 14 stented arteries. Three stents were occluded, one stent showed some neointimal hyperplasia (50–70% restenosis), the remaining ten stents showed no restenosis (0–30%). The use of self-expanding nitinol stents in tibioperoneal and popliteal arteries is a safe and feasible option for the treatment of unsuccessful PTA. The 6-months patency is high.     

Stent Compression in Iliac Vein Compression Syndrome Associated with Acute Ilio-Femoral Deep Vein Thrombosis

ObjectiveThis study was conducted to evaluate stent compression in iliac vein compression syndrome (IVCS) and to identify its association with stent patency.ResultsAll of the stents used were laser-cut nitinol stents. The proportion of limbs showing significant stent compression was 33%. Fifty-six percent of limbs in the significant stent compression group developed stent occlusion. On the other hand, only 9% of limbs in the insignificant stent compression group developed stent occlusion. Significant stent compression was inversely correlated with stent patency (p < 0.001). The median patency period evaluated with Kaplan-Meier analysis was 20.0 months for patients with significant stent compression. Other factors including gender, age, and type of stent were not correlated with stent patency. Significant stent compression occurred most frequently (87.5%) at the upper end of the stent (ilio-caval junction).ConclusionSignificant compression of nitinol stents placed in IVCS highly affects stent patency. Therefore, in order to prevent stent compression in IVCS, nitinol stents with higher radial resistive force may be required.     

金属与塑料支架姑息性治疗恶性胆道梗阻疗效对比研究

目的 :比较经皮肝穿金属支架与塑料支架置入术姑息性治疗恶性梗阻性黄疸的临床疗效及开通时间 ,探讨两种支架治疗的适应证。方法 :对 45例金属支架与 3 4例塑料支架介入治疗恶性梗阻性黄疸的临床资料进行回顾性分析。结果 :两组术后对降低胆红素和改善临床症状均有明显疗效 ,选择病例以肝门部梗阻占多数。术后早期并发症较少 ,晚期并发症主要为支架阻塞。金属支架中位开通时间为 2 76d ,明显长于塑料支架的 112d(P <0 .0 1)。结论 :两种支架均能有效解除胆道梗阻 ,且对高位梗阻具有优势 ,适用于不宜手术者。金属支架开通期明显长于塑料支架 ,但价格较贵 ;估计生存期 >3个月者 ,宜选择金属支架 ;生存期 <3个月和 /或经济条件不许可者 ,可选用塑料支架     

Budd-Chiari syndrome due to prothrombotic disorder: mid-term patency and efficacy of endovascular stents

Our objective was to evaluate efficacy and patency of metallic stent placement for symptomatic Budd-Chiari syndrome (BCS) due to prothrombotic disorders. Eleven patients with proved BCS due to prothrombotic disorders were referred for endovascular treatment because of refractory ascites (n=9), abdominal pain (n=8), jaundice (n=6), and/or gastrointestinal bleeding (n=4). Stents were inserted for stenosed hepatic vein (n=7), inferior vena cava (n=2), or mesenterico-caval shunt (n=2). Clinical efficacy and stent patency was evaluated by clinical and Doppler follow-up. After a mean follow-up of 21 months, 6 patients had fully patent stents without reintervention (primary stent patency: 55%). Two patients with hepatic vein stenosis had stent thrombosis and died 4 months after procedure. Restenosis occurred in 3 cases (2 hepatic vein and 1 mesenterico-caval shunt stenosis) and were successfully treated by balloon angioplasty (n=2) and addition of new stents (n=1) leading to a 82% secondary stent patency. Of 9 patients with patent stent, 7 were asymptomatic (77%) at the end of the study. Stent placement is a safe and effective procedure to control of symptomatic BCS. Prothrombotic disorder does not seem to jeopardize patency in anticoagulated patients. Electronic Publication     

犬颈外动脉置入国产颅内动脉支架的实验研究

目的:评价国产颅内动脉支架的轴向柔顺性、径向支撑力、致血栓性、X线可见性。方法:将6只健康家犬随机分成3组,通过介入导管技术将国产支架置入犬双侧颈外动脉远端分支,分别在支架置入后10min(n=12)、1周(n=4)、4周(n=4)、24周(n=4)进行颈外动脉造影,观察支架情况并测量靶血管直径。结果:6只家犬共成功置入国产支架12个,无支架脱落、球囊破裂等。支架易于通过纡曲的颈外动脉虹吸部到达靶血管,支架扩张后靶血管扩张达到预定直径(术前与术后10min靶血管直径差异有显著性意义,P<0.05)。支架置入后10min颈外动脉造影显示血管无夹层、穿孔、撕裂等异常,靶血管内无急性血栓形成,1支靶血管远端小血管发生急性血管闭塞;支架置入后1周、4周、24周颈外动脉造影显示:靶血管开通良好,无明显狭窄,支架无移位和回缩;靶血管狭窄程度<50%,与术前相比有明显改善,透视下支架显影清晰。结论:国产颅内动脉支架具有轴向柔顺性好,可以通过纡曲血管;径向支撑力强,无移位和回缩;致血栓性低和X线可见性好等优点。     

髋关节区动脉支架植入治疗下肢动脉重症缺血的临床效果评价

目的观察与评价髋关节区支架植入治疗下肢动脉重症缺血的安全性、有效性及对股深动脉血流的影响。 方法66例动脉硬化闭塞所致下肢重症缺血患者（共70条动脉,均累及股总动脉和/或股动脉近心段）。平均年龄74.6岁。男46例,女20例。左下肢动脉40条,右下肢动脉30条。开通闭塞动脉后,行球囊扩张及支架植入。 结果术中股动脉急性闭塞3例（局部溶栓后获得通畅）,余下肢动脉即刻血流均获得通畅,下肢缺血症状均明显改善。术后15例患肢出现血流过度灌注,无严重并发症发生。随访54例（失访12例）,随访时间2～30个月,平均（16.2±2.6）个月。25例因再狭窄或闭塞发生患肢缺血,其中16例接受再次介入治疗（PTA及导管溶栓后获二次通畅）。跨髋关节支架均无断裂,股深动脉均仍保持通畅。6例发生心、脑血管意外,其中2例死亡。 结论跨髋关节动脉支架植入可安全、有效地改善下肢动脉重症缺血,且不影响股深动脉血流。     

A novel self-expanding fully retrievable intracranial stent (SOLO): experience in nine procedures of stent-assisted aneurysm coil occlusion

Introduction The endovascular treatment of large and broad-necked aneurysms may require the use of a remodelling balloon or a stent system to achieve proper occlusion while maintaining the patency of the parent vessel. With the advent of self-expanding stents that can be delivered through a microcatheter, this kind of treatment has improved and problems with the previously used balloon expandable stents have largely been overcome. However, rigidity, insufficient trackability, and limited or non-existent retrievability may still restrict the application of self-expanding stents in some situations. Methods Recently, a stent system with a new and different design has been introduced. This stent is highly flexible, fully retrievable, and can be delivered through a standard 0.021-inch microcatheter without a wire. We describe the first nine cases of stent-assisted coil occlusion of intracranial aneurysms with the use of this stent system. Between May and June of 2004, nine patients with large or broad-necked aneurysms were treated in two endovascular centres. The anatomy of the aneurysms and parent vessels, technical details of the procedure, performance of the stent system, and follow-up results were evaluated. Results In all procedures, the SOLO stent could be introduced without difficulty, in one procedure after positioning of a different self-expanding stent system had failed due to vessel tortuosity. Overlapping stents were placed in one patient and stent retrieval or repositioning was successfully performed in two procedures. There was no interference or limitation of subsequent coil occlusion after stenting. With regard to the stent, immediate postprocedure and follow-up angiograms were unremarkable in terms of thromboembolic events and signs of intimal hyperplasia. Conclusion From our experience, we conclude that the SOLO stent shows satisfactory performance overall. Its unique design gives the stent properties that may help overcome some of the difficulties experienced with other self-expanding intracranial stent systems.     

血管内支架结合电解可脱弹簧圈治疗颅内动脉瘤

目的 初步总结使用血管内支架结合电解可脱卸弹簧圈（GDC）治疗颅内梭形及宽颈动脉瘤的体会,探讨其适应证、方法、疗效及并发症。方法 5例颅内梭形动脉瘤及12例宽颈动脉瘤,首先将冠脉支架跨动脉瘤颈放置,通过支架的网孔将微导管送入动脉瘤腔,继续填塞GDC。结果 13例动脉瘤致密填塞,3例大部分填塞,1例支架未能送入颅内而单用弹簧圈部分栓塞,载瘤动脉通畅,临床效果优良。结论 联合使用支架及微弹簧圈是治疗颅内梭形及宽颈动脉瘤的有效方法,远期疗效需进一步随访。     

支架结合弹簧圈治疗颅内宽颈动脉瘤急性破裂的可行性和安全性

目的　总结血管内支架结合电解可脱卸弹簧圈 (GDC)治疗颅内宽颈动脉瘤急性破裂的临床体会 ,对其可行性和安全性进行初步探讨。方法　 5 7例急性破裂宽颈动脉瘤 ,均先植入冠脉支架覆盖动脉瘤颈 ,再将微导管通过支架网孔超选进入动脉瘤腔内填塞GDC。结果　 1例因血管扭曲不能植入支架 ,5 6例成功 ,均达到 90 %以上栓塞 ,载瘤动脉通畅 ,所有患者无神经功能障碍出现。结论　血管内支架植入结合GDC填塞是治疗急性破裂宽颈动脉瘤的安全、可行的方法     

自制金属内支架的动物实验研究

目的：研究自制镍钛记忆合金内支架的生物相容性及通畅情况。方法：通过外科手术方式将自制镍钛记忆合金内支架放置于猪的胆管、支脉、静脉、气管中，于术后的一段时间内，处死实验动物，观察内支架的通畅情况。结果：１１只胆道支架有６只完全阻塞，有５只支架部分通畅，且阻塞程度与时间有关；１０／１１只股动脉支架均显著通畅。仅１只支架完全阻塞；１／１静脉支架完全阻塞；４／８只气管支架通畅。４只支架表面取了脱落细胞检查     

Development of gold stents for the treatment of intracranial aneurysms: an experimental study in a canine model

BACKGROUND AND PURPOSE: Gold has often been used in medicine because of its radiopacity and flexibility. To perform stent-supported coil embolization of intracranial aneurysms, we prepared a gold stent and examined its flexibility, radiopacity, and thrombogenic properties in comparison with a stainless steel device implanted in vitro and in vivo. METHODS: Gold stents were prepared by plating gold on stainless steel stents as a template. Their mechanical properties and trackability in vitro were determined and compared with those of stainless steel stents of the same design. Twenty gold stents and two stainless steel stents were implanted in canine external carotid, vertebral, and renal arteries, as a muscle branch of the maxillary arteries, to examine their performance in vivo. RESULTS: The gold stent exhibited much less radial force and greater flexibility than the stainless steel stent. It also demonstrated superior trackability and radiopacity in the experimental endovascular procedures in canines. Histologic examination showed good patency of the stented artery with slight endothelial hypertrophy. CONCLUSION: Although there is still room for more radial strength, less influence on intimal hypertrophy, a more suitable flexibility, and a smoother surface, the superior trackability and radiopacity of gold stents seem to support use of this device for the endovascular treatment of intracranial aneurysms.     

Percutaneous Unilateral Biliary Metallic Stent Placement in Patients with Malignant Obstruction of the Biliary Hila and Contralateral Portal Vein Steno-Occlusion

Objective

To investigate the outcomes of percutaneous unilateral metallic stent placement in patients with a malignant obstruction of the biliary hila and a contralateral portal vein steno-occlusion.

Materials and Methods

Sixty patients with a malignant hilar obstruction and unilobar portal vein steno-occlusion caused by tumor invasion or preoperative portal vein embolization were enrolled in this retrospective study from October 2010 to October 2013. All patients were treated with percutaneous placement of a biliary metallic stent, including expanded polytetrafluoroethylene (ePTFE)-covered stents in 27 patients and uncovered stents in 33 patients.

Results

A total of 70 stents were successfully placed in 60 patients. Procedural-related minor complications, including self-limiting hemobilia (n = 2) and cholangitis (n = 4) occurred in six (10%) patients. Acute cholecystitis occurred in two patients. Successful internal drainage was achieved in 54 (90%) of the 60 patients. According to a Kaplan-Meier analysis, median survival time was 210 days (95% confidence interval [CI], 135-284 days), and median stent patency time was 133 days (95% CI, 94-171 days). No significant difference in stent patency was observed between covered and uncovered stents (p = 0.646). Stent dysfunction occurred in 16 (29.6%) of 54 patients after a mean of 159 days (range, 65-321 days).

Conclusion

Unilateral placement of ePTFE-covered and uncovered stents in the hepatic lobe with a patent portal vein is a safe and effective method for palliative treatment of patients with a contralateral portal vein steno-occlusion caused by an advanced hilar malignancy or portal vein embolization. No significant difference in stent patency was detected between covered and uncovered metallic stents.     

颅内自膨胀支架结合弹簧圈治疗脑动脉瘤

目的　报道采用自膨胀颅内专用支架 (Neuroform支架 )结合弹簧圈栓塞治疗颅内宽颈动脉瘤 ,初步探讨该支架的特点、短期疗效及应用前景。方法　采用Neuroform支架结合弹簧圈栓塞治疗 32例 34枚颅内宽颈动脉瘤。颈内动脉海绵窦段 3例 ,眼动脉 3例 ,后交通动脉 8例 ,前交通动脉 3例 ,大脑中动脉分叉部 5例 ,椎动脉 6例 ,基底动脉顶端 1例 ,基底动脉干 2例 ,大脑前动脉A3段 1例 ,多发动脉瘤 2例。通过Renegade微导管释放Neuroform支架覆盖动脉瘤瘤颈 ,预先将另一微导管置入动脉瘤腔或将微导管通过支架网孔以弹簧圈栓塞动脉瘤。结果　 31例 34个支架成功到位释放 ,1例基底动脉顶端动脉瘤因支架无法通过狭窄的大脑后动脉而改用BX支架。 3例 1次各置入 2枚支架。 2 4例致密栓塞 ,6例瘤颈残留 ,2例部分栓塞。 1例术中发生支架内血栓 ,死亡 1例 ,其余患者均恢复良好出院。临床随访 30例 ,随访期 1～ 6个月 ,平均 4 .7个月 ,无再出血及血栓栓塞症状发生。 1 1例术后 3个月血管造影随访 :7例致密栓塞的动脉瘤均未显影 ;4例瘤颈残留者 ,2例无变化 ;2例原有瘤颈残留未再显影。结论　Neuroform支架技术上容易操控 ,顺应性好 ,安全性高 ,可以到达颅内较远端的血管 ,大大扩展了支架技术治疗颅内血管病变的应用范围 ,近期     

Self-expanding metallic stents for small vessels: an experimental evaluation

Thirty-three self-expanding metallic stents were placed in 24 arterial segments of the hind legs and nine arteries of the abdominal viscera in seven dogs. Twelve 5-mm stents, eight 4-mm stents, and 13 3-mm stents were inserted. Follow-up ranged from 4 to 30 weeks. All 4-mm and 5-mm stents were patent at follow-up. Seven (54%) of the 3-mm stents remained patent. Stent wires were completely covered by a proliferation of the intima. No stent migration, occlusion of side branches, or vessel wall perforation was observed. A stent/artery ratio (SAR) was computed using stent and recipient vessel diameters. Good vascular patency was observed when the SAR was less than or equal to 1.2. An SAR greater than 1.2 was associated with immediate spasm, immediate or delayed thrombosis, or excessive intimal proliferation. Selection of correct stent size is a major determinant of patency in small arteries.     

Treatment of wide-necked intracranial aneurysms with a self-expanding stent system: initial clinical experience

BACKGROUND AND PURPOSE: Currently available stents for intracranial use usually are balloon-expandable coronary stents that carry the risk of damaging a dysplastic segment of the artery, with potential vessel rupture. We assessed the technical feasibility and efficacy of the combined application of a flexible, self-expanding neurovascular stent and detachable coils in the management of wide-necked intracranial aneurysms in humans. METHODS: Four consecutive patients with a wide-necked intracranial aneurysm were treated with a combined approach that consisted of delivery of a flexible self-expanding neurovascular stent through a microcather to cover the neck of the aneurysm and subsequent filling of the aneurysm with coils through the stent interstices. The aneurysms were located at the internal carotid artery (n=2) and the basilar tip encroaching the P1 segment (n=2). Previous attempts with conventional endosaccular coil packing alone failed in all cases. RESULTS: Stent placement in the desired position with complete or nearly complete occlusion of the aneurysms was feasible in all patients. In one patient, aneurysm perforation with the microcatheter occurred and necessitated ventricular drainage, which led to a large parenchymal and intraventricular hemorrhage because of the strong anticoagulation regimen. Six-month follow-up demonstrated no focal neurologic sequelae in any of the patients, except slight memory dysfunction in the patient with bleeding. CONCLUSION: Preliminary data demonstrate that this extremely flexible stent is technically easy to deploy and can be easily and safely maneuvered through severely tortuous vessels, enabling the treatment of intracranial wide-necked aneurysms. The combination of endovascular reconstruction of the parent vessel with use of a self-expanding stent followed by coil embolization offers a promising therapeutic alternative for wide-necked aneurysms not amenable to coil embolization alone. Although immediate angiographic results are promising, long-term angiographic and clinical follow-up is essential to determine permanent vessel patency and aneurysm occlusion rate.