Rheological Changes After Stenting of a Cerebral Aneurysm: A Finite Element Modeling Approach

Hemodynamic changes in intracranial aneurysms after stent placement include the appearance of areas with stagnant flow and low shear rates. We investigated the influence of stent placement on blood flow velocity and wall shear stress of an intracranial aneurysm using a finite element modeling approach. To assess viscosity changes induced by stent placement, the rheology of blood as non-Newtonian fluid was taken into account in this model. A two-dimensional model with a parent artery, a smaller branching artery, and an aneurysm located at the bifurcation, before and after stent placement, was used for simulation. Flow velocity plots and wall shear stress before and after stent placement was calculated over the entire cardiac circle. Values for dynamic viscosity were calculated with a constitutive equation that was based on experimental studies and yielded a viscosity, which decreases as the shear rate increases. Stent placement lowered peak velocities in the main vortex of the aneurysm by a factor of at least 4 compared to peak velocities in the main artery, and it considerably decreased the wall shear stress of the aneurysm. Dynamic viscosity increases after stent placement persisted over a major part of the cardiac cycle, with a factor of up to 10, most pronounced near the dome of the aneurysm. Finite element modeling can offer insight into rheological changes induced by stent treatment of aneurysms and allows visualizing dynamic viscosity changes induced by stent placement.     

Treatment of intracranial atherosclerotic stenoses with balloon dilatation and self-expanding stent deployment (WingSpan)

The endovascular treatment of atherosclerotic intracranial arterial stenoses has previously been based on balloon dilatation or the deployment of a balloon expandable stent. Both methods have advantages (balloon: flexibility; balloon expandable stent: high radial force) and drawbacks (balloon: risk of elastic recoil and dissection; balloon expandable stent: limited flexibility, risk of injury to the vessel due to excessive straightening, overexpansion at ends of stent). A new combination of balloon dilatation, followed by the deployment of a self-expanding microstent has been applied in 15 patients with atherosclerotic arterial stenoses, symptomatic despite medical treatment. An anatomically and clinically adequate result was achieved in all patients. The initial degree of stenosis was 72% (mean). Balloon dilatation resulted in an average residual stenosis of 54% (mean), reduced further to a mean of 38% after stent deployment. Arterial dissection, occlusion of the target artery or symptomatic distal emboli was not encountered. In one patient, a side branch occlusion occurred after dilatation of a M1 stenosis, with complete neurological recovery. All patients were either stable or improved 4 weeks after the treatment. Recurrent TIA did not occur in any patient. Balloon dilatation and subsequent deployment of a self-expandable stent for the treatment of symptomatic intracranial arterial stenoses combines the advantages of both techniques and allows a rapid, clinically effective and technically safe treatment of these frequently challenging lesions.     

64层螺旋CT在冠状动脉支架置入术后评估中的价值

目的:评价64层螺旋CT在冠状动脉支架置入术后复查中的临床价值。方法:采用64层螺旋CT对27例冠状动脉支架置入术后的患者(共47个支架)进行CT冠状动脉成像。观察支架及其支架血管和非支架血管的通畅性。结果:支架通畅43例,支架内狭窄3个、闭塞1个,支架前后血管狭窄25支(包括两近端狭窄4例),非支架血管狭窄26支。结论:64层螺旋CT比16层螺旋CT观察冠状动脉内支架优越,可作为冠状动脉支架置入术后效果随访观察和了解原有冠心病进展情况的重要手段。     

颈动脉支架治疗颈动脉狭窄的并发症

目的 探讨颈内动脉狭窄血管内支架治疗的并发症.方法 对648例颈内动脉狭窄患者行全脑血管造影及颈部超声检查.365例患者使用脑保护装置,283例未使用保护装置283例.结果 648例患者技术成功率为100%,患者症状消失或好转率为78.7%.心率＜50次/min者占26.4%;术中栓子脱落5例,其中3例治疗后恢复,2例遗留一侧肢体运动障碍,术后颅内出血死亡3例,术后30 d内总脑卒中或死亡6例,占1.2%.随访率为77 8%.再狭窄17例,占3.3%.结论 颈内动脉狭窄的血管内支架治疗是安全的,但术前对临床及影像学检查正确评价,术中规范化操作及术后规范化护理,是减少并发症的关键.     

血管内支架成形术治疗颅内动脉狭窄

目的:探讨颅内动脉狭窄血管内球囊支架成形术的可行性、安全性及其疗效。方法:17例患者术前3天给予阿司匹林300mg/天和噻氯吡啶250mg/天,6F(Envoy)导引导管放置到颈内动脉远段或椎动脉近颅底段,造影获得工作位,评价血管狭窄程度:狭窄率=(1-狭窄处管径/狭窄远端管径)×100%,微导丝在路途导引下通过颅内动脉狭窄段,向远端直至P2或M2段,确保足够的支撑力。选择支架大小的依据为狭窄远端正常血管的直径,导丝引导下支架通过狭窄部位,造影确定支架位置正确,充盈球囊至5～6大气压,支架释放后造影确认展开良好,回撤球囊,无并发症,操作完毕。随访3～10月。结果:17例患者颅内动脉狭窄处植入支架,技术成功100%,造影显示狭窄由术前(78.3±12.9)%降至术后(6.8±7.3)%,狭窄的动脉管径恢复,短期随访(3～10个月)显示很好临床效果。术中出现一例蛛网膜下腔少量出血(SAH),对症治疗痊愈。6例随访造影未见血管再狭窄。结论:颅内动脉狭窄支架植入增加血管内径,改善血流量,减轻临床症状,是一种安全、可行有效的治疗方法。     

金属支架治疗大气道狭窄

目的　探讨气管支架成形术缓解大气道狭窄的方法、安全性和疗效。资料与方法　气管狭窄患者 32例 ,其中气管切开或插管后局部组织过度增生 7例 ,转移性肿瘤压迫气管 12例 ,多发性软骨炎引起气管塌陷 1例 ,肺癌 12例 ;单纯气管狭窄 2 8例 ,主支气管狭窄 1例 ,气管支气管同时有狭窄者 3例。术前均经CT检查及气管体层片证实气管、支气管狭窄。 13例术前用的卡因喷喉麻醉 ,19例在全身麻醉下置入支架。结果　 32例共放置 37枚气管支架 ,均一次置入成功 ,无操作失败 ,通气全部得到改善 ,手术成功率 10 0 %。 2例气管狭窄经置入支架后复发狭窄再次置入支架。 33枚置于气管 ,4枚置于主支气管。 1例狭窄严重仅容 4F导管通过 ,用球囊导管扩张至 12mm后置入支架 ;其余均直接置入支架。术后通气功能明显改善 ,无需吸氧 ,无明显胸痛、咯血等并发症。 1周后X线复查无支架移位 ,可见支架进一步扩张。 1例甲状腺癌支架置入术后 2周复发呼吸困难 ,CT扫描示支架内有新生物 ,经支架内放射治疗后症状消失。结论　气管内支架成形术方法简单、安全 ,缓解呼吸困难疗效迅速、确实 ,适合良恶性气道狭窄姑息治疗     

支架联合弹簧圈技术栓塞颅内微小宽颈动脉瘤

目的　探讨三维 (3D)数字减影 (DSA)辅助下血管内支架联合弹簧圈 (stent coil)技术栓塞颅内微小宽颈动脉瘤的技术要点及疗效。方法　 12例瘤体 颈比值≤ 1的颅内微小宽颈动脉瘤 (瘤体最大径≤ 4 .0mm) ,全部经二维 (2D)造影及 3D重建 ,前交通动脉 2例采用双侧置管 ,微导管头端到位后 ,通过对侧导引导管内释放颅内自膨胀支架Neuroform ,再通过微导管使用弹簧圈塞动脉瘤。后交通动脉 8例 ,小脑后下动脉动脉起始部 2例 ,先释放支架覆盖瘤颈 ,通过支架网眼将微导管送入动脉瘤腔使用弹簧圈栓塞 ,术后 6～ 12个月进行临床和影像学随访。结果　 12例 2DDSA检查中 7例需经 3D确定为宽颈动脉瘤 ;12例全部技术成功 ,动脉瘤致密栓塞 ,载瘤动脉通畅 ;1例前交通动脉瘤栓塞后出现一过性神经功能障碍 ,经治疗后恢复正常 ,其余 11例恢复顺利。 12例临床随访 6～ 12个月 ,无动脉瘤再出血或脑血栓形成 ,7例DSA随访 ,无支架内膜增生狭窄及动脉瘤复发。结论　 3DDSA在颅内微小宽颈动脉瘤的诊断和介入治疗中有重要的辅助作用 ,支架～弹簧圈技术栓塞颅内微小宽颈动脉瘤疗效确实 ,颅内专用支架为特殊部位宽颈动脉瘤的介入治疗提供了方便。     

腘动脉穿刺逆行内膜下血管成形术治疗股浅动脉起始部长段硬化性闭塞疾病

目的：探讨经腘动脉逆行内膜下血管成形术（subintimal angiop lasty,SIA）治疗股浅动脉起始部长段闭塞疾病的临床效果和应用价值。方法：经腘动脉穿刺逆行SIA治疗股浅动脉起始部长段慢性硬化闭塞19例,采用PTA＋内支架（stent）置入。结果：全组治疗成功率100%（19/19）,无严重并发症发生;19例股浅动脉闭塞经腘动脉穿刺逆行SIA后,随访3~48个月,血流仍保持通畅为94.74%（18/19）,1例股浅动脉逆行SIA并支架置入12个月出现再阻塞,经局部溶栓,支架腔内血流均保持通畅。术前术后踝肱指数（ankle brachial index,ABI）平均0.25（0.12~0.43）和0.89（0.69~1.08）,两者比较差异有统计学意义（P〈0.05）。结论：经腘动脉逆行SIA是治疗股浅动脉起始部长段硬化闭塞,所致慢性严重肢体缺血的安全有效的方法。     

移植肾动脉狭窄的介入治疗

目的研究移植肾动脉狭窄(TRAS)的临床特点及介入治疗的疗效。方法回顾性分析TRAS患者的临床资料,排除临床资料不完整者,分析总结其临床特点、诊断方法及介入治疗的疗效。结果共搜集病例31例,行介入手术35次。6例行单纯球囊扩张(PTA),24例行支架置入,1例手术失败。术后肾动脉狭窄程度、肾功能及血压明显改善,围手术期未发生严重并发症;平均随访29.6个月,PTA术后2例(33.3%)复发狭窄,行支架置入术无复发;支架术后3例(12.5%)再发狭窄,2例成功行PTA术后无复发。结论肾移植术后密切超声随访有利于早期诊断TRAS,介入治疗TRAS安全、有效且应被视为一线治疗方法。