冠状动脉分叉病变单支架植入术后血流动力学分析

目的分叉病变在即刻手术成功率及远期心脏事件方面是最具有挑战的冠脉病变之一。血流动力学对动脉粥样硬化的形成有重要影响。对分叉病变单支架虚拟植入后的血流动力学参数分布进行分析,探讨其对支架后再狭窄的影响,可为临床治疗提供理论依据。方法本文选取一例冠状动脉分叉病变患者的冠状动脉血管造影(computed tomography angiography,CTA)图像,首先用Mimic软件对所获得冠脉CTA数据进行三维重建得到冠脉血流区域,然后运用类似虚拟去除斑块的方式建立不均匀壁厚血管壁模型,对所得模型在ABAQUS中进行单支架虚拟植入,最后根据虚拟植入前、后的冠脉模型分别生成支架前和真实变形后的血流域有限元模型,并利用ANSYS软件通过瞬态CFD分析模拟动脉血流的流动状态,获得目标血管段的血流动力学参数。结果支架植入后与支架植入前相比,目标血管段的血液流速、壁面剪切应力均降低;支架植入后主支血管远端有振荡的低剪切应力区域;支架边缘位置壁面剪切应力低于其他位置;分支血管直径变小;分支外侧壁壁面剪切应力低于内侧壁。结论分叉病变的单支架植入可改善冠脉主支的狭窄,但术后主支血管远端振荡的低剪切应力区域、支架边缘和边支外侧壁处的低壁面剪切应力,以及斑块和分叉嵴的移位有可能是分叉病变再狭窄的血流动力学机制。     

远端侧-侧吻合冠脉搭桥术后血栓形成的数值模拟

目的 研究桥血管远端不同处理方式对其血栓生成的不同影响。方法 针对远端侧-侧吻合(distal-end side-side anastomosis, DESSA)冠脉搭桥术,构建桥血管远端裁剪和不裁剪两种模型。使用生化反应的血液物质传输扩散模型,同时考虑血流动力学的切变率、流体滞留时间和血小板分布参数,评估血栓形成的可能性,使用数值模拟方法探讨DESSA冠脉搭桥中血栓生长。结果 对于桥血管远端无裁剪处理的模型,血栓首先在桥血管远端内壁面上形成,随后向其内部生长,直至血栓占满大部分桥血管远端区域,血栓进入稳定状态,体积不再变化,生成血栓体积为15.051 mm³。对于桥血管远端裁剪处理模型,生成血栓体积为7.352 mm³,同远端无裁剪模型相比,生成血栓体积减小51.2%。桥血管远端裁剪处理后,吻合口上方桥血管内壁上有血栓生成,壁厚约为0.16 mm,为桥血管半径的10.65%。上述两种术式中,桥血管远端区域形成多个漩涡流(流速小于10 mm/s),促进桥血管远端血栓形成;计算结果和临床报道的血栓形成区域相一致。结论 临床DESSA冠脉搭桥术时...     

血管内支架表面生物涂层材料与血管内再狭窄

背景：心脏病是威胁人类健康的首要病因之一,现在全世界每年大约有1 500万例冠心病患者需要接受经皮穿刺冠状动脉(冠脉)成形治疗,但是大约10%发生急性或亚急性冠脉阻塞,6个月后再狭窄发生率高达20%~50%,再狭窄已成为制约经皮穿刺冠状动脉(冠脉)成形术发展的最主要因素。 目的：探讨药物洗脱支架治疗支架内再狭窄的长期临床效果。 方法：作者以“药物洗脱支架,阻塞,再狭窄”为检索词,在中国期刊全文数据库中,采用电子检索的方式进行文献检索。排除Meta分析及重复性研究,共检索到25篇文献,从支架置入治疗进展,不同材料及类型支架对开通率、开通时间的影响,以及预防支架狭窄等方面进行探讨。 结果与结论：药物洗脱支架运用先进的支架载药及药物控制释放技术,在支架机械支撑病变血管的同时,具有抑制血管平滑肌细胞增生的药物从支架表面缓慢释放,作用于与支架接触的血管壁,解决了血管弹性回缩、重塑以及内膜的过度增生问题。随着冠状动脉介入治疗设备的改进和创新,药物涂层支架技术也在不断地成熟和发展。目前新出现的药物涂层支架设计理念是建立在药物筛选和可控释放系统基础上的。相信未来的药物涂层支架将能够应用于更多的血管复杂病变(尤其是静脉和多血管损伤)以及其他脏器疾病。     

冠状动脉支架置入患者血清炎症因子表达及血管再狭窄

目的：评价冠状动脉支架置入后血清炎症因子对再狭窄形成的影响。 方法：以“冠状动脉疾病,冠状动脉支架置入,炎症介导,支架材料”为检索词,检索中国期刊文数据库及Medline数据库2001/2010相关文献。纳入研究对象为冠状动脉粥样硬化性心脏病需要支架置入治疗的患者;经冠状动脉造影检查证实为冠心病的患者;不限定患者的年龄、性别、种族及地域,且同意行冠状动脉支架置入治疗;检测指标为炎症因子表达。排除感染性疾病、出血性疾病、白血病、严重肝病、严重肾功能不全及肿瘤者。重点对23条文献进行探讨。 结果：支架置入后随着血清可溶性细胞间黏附分子1浓度增加sCD40L浓度也增加。支架置入后血清可溶性细胞间黏附分子1、基质金属蛋白酶9浓度均明显升高,并上调了黏附因子血清可溶性细胞间黏附分子1、基质金属蛋白酶9的表达;对血清白细胞介素18及C-反应蛋白的水平有明显影响。 结论：结果说明在支架置入过程中,球囊扩张、支架置入等一系列挤压斑块因素, 促进了炎症因子释放,增加了血清炎症因子的水平。冠脉血管损伤后血管重构及再灌注也是促其增高的原因,而升高幅度与冠脉病变程度密切相关。     

丹红注射液对冠状动脉支架置入患者血管内皮功能的影响(英文)

背景:众多研究证实丹参能抑制中性粒细胞的黏附、聚集及氧自由基的产生,具有活血化瘀的疗效,但目前对于其保护血管内皮以及抗血栓形成具体机制,尤其是在冠状动脉支架置入后作用机制的研究很少。目的:观察丹红注射液对急性冠脉综合征患者冠状动脉支架置入前后血管内皮功能的影响。方法:采用随机对照方法将60例急性冠脉综合征患者分为2组,常规治疗组在冠状动脉支架置入后给予常规药物治疗;丹红组在冠状动脉支架置入后给予常规药物治疗基础上加用丹红注射液20mL/d,疗程10d。支架置入前后及丹红治疗前后测定内皮依赖性血流介导的血管舒张反应、血浆内皮素、血栓烷B2、6-酮-前列腺素水平,双重评价其血管内皮功能;同时观察两组患者近期预后。结果与结论:与支架置入前比较,支架置入后两组患者血浆内皮素、血栓烷B2均明显提高,6-酮-前列腺素水平明显下降(P0.05)。与支架置入后比较,两组治疗后血浆内皮素、血栓烷B2均明显降低(P0.05,P0.01);内皮依赖性血流介导的血管舒张反应、6-酮-前列腺素明显提高(P0.05,P0.01),丹红组更明显(P0.05)。住院期间丹红组心血管事件发生较常规治疗组略有下降,但差异无显著性意义(P0.05)。结果表明丹红注射液可显著改善支架置入急性冠脉综合征患者血管内皮功能,使血管舒张,改善供血,抑制血小板聚集,且有改善近期预后的倾向。     

低剂量双源CT冠状动脉成像在支架置入后复查中的应用

背景：多排螺旋CT冠状动脉造影目前已成为评价冠脉支架置入后的检查重要手段,但患者需要接受较大的X射线剂量。 目的：评价低剂量双源CT冠状动脉造影成像技术在冠状动脉支架置入后复查中的应用价值。 方法：采用双源CT冠状动脉造影成像技术对45例冠状动脉支架置入后的患者进行前门控CT冠状动脉扫描,共置入支架63枚,观察支架及非支架血管的通畅性,与数字减影血管造影金标准进行对比;并随机抽取应用后门控法行双源CT冠状动脉造影成像的50例患者,以作辐射剂量对比。 结果与结论：与数字减影血管造影对比,前门控组双源CT冠状动脉造影成像诊断支架内通畅性正确率为96.8%,非支架血管通畅性正确率为96.5%。前门控组所接受的辐射剂量显著低于后门控组(P < 0.01)。提示低剂量双源CT冠状动脉造影成像技术在心率(律)允许的条件下,可以在保证检查质量的同时大幅降低患者的辐射剂量,可作为冠状动脉支架置入后效果评价和随访的重要手段。     

应用支架内锚定技术开通前降支闭塞病变1例

正冠状动脉闭塞、分叉及扭曲病变是目前冠脉介入治疗中最具挑战性的病变类型,但由于局部血管解剖结构或支架的阻力,介入治疗器械(如球囊等)无法通过病变部位,无法进行扩张或支架置入,导致手术失败。Fujita等[1]发明的边支锚定技术对促进介入治疗器械通过闭塞病变有巨大的帮助,但在长期的临床实践中发现此法有弊端,如血管内球囊扩张锚定导致的血管夹层,血栓及闭塞等安全问题;球囊锚定扩张压力小于     

串联药物洗脱支架治疗冠状动脉弥漫性长病变的远期疗效

目的:评价串联药物洗脱支架(DES)治疗冠状动脉弥漫性长病变的远期临床疗效。方法:回顾性分析233例冠状动脉弥漫性长病变且成功接受串联DES置入术或单个长DES置入术的冠心病患者,根据置入支架方式及长度的不同,分为A组:置入串联DES且支架总长度34-59mm(n=85);B组:置入串联DES且支架总长度60-95mm(n=71);C组:置入单个长DES且支架长度35-38mm(n=77)。比较各组术后第1年和第2年主要不良心血管事件(MACE)和支架内再狭窄(ISR)发生率的差异。结果:术后第1年和第2年,三组间MACE和ISR的发生率差异无统计学意义(P>0.05)。结论:串联DES且支架总长度≥60mm治疗冠状动脉弥漫性长病变的远期临床疗效总体满意,安全可行。     

药物洗脱支架置入弯曲冠状动脉血管后药物浓度场及壁面切应力分布

背景:血管闭塞性疾病主要治疗方法之一,支架置入的后期再狭窄问题开始制约支架的进一步发展。目的:分析药物洗脱支架置入弯曲冠脉血管后的药物浓度场及壁面切应力分布规律,为临床应用及药物洗脱支架的进一步完善提供理论指导。方法:选取3种药物释放率情况,采用数值方法对药物洗脱支架置入弯曲冠脉后的药物浓度场和壁面切应力情况进行分析。结果与结论:血管的弯曲和支架的置入对药物扩散的浓度场有较大影响。药物释放速率的改变对浓度分布规律没有影响。由于流场分布的不均匀,弯曲冠脉血管内侧的药物浓度高于外侧,下游的浓度高于上游。外侧支架附近的血管壁上出现低切应力区,加上低的药物浓度分布,使得这些位置(特别是上游区域)成为再狭窄萌发的高危险区。结果提示,如果根据置入支架所处位置的流场分布特点,有意识的对支架表面载药量的分配分布进行合理的优化,适当增加上游和外侧药物涂层的浓度,减少下游和内侧涂层的浓度;增加径向连接筋的载药量,减少连接筋数目,充分利用流动带来的上游药物浓度,使得血管壁附近的药物浓度分布更加均匀合理,这将既节省药量,又有利于抑制内膜增生。     

基于"心肌桥-冠状动脉"模拟装置的周向应力研究

研制一种心肌桥压迫冠状动脉的模拟装置,用以研究壁冠状动脉近端与远端周向应力的动态变化,并可实现其独立调节.制作"心肌桥-冠状动脉"模拟装置,分别改变模拟冠状动脉外压和心肌桥压迫程度并记录周向应力的变化情况.结果表明,周向应力的异常主要位于壁冠状动脉近端,随着心肌桥压迫程度加剧,近端的周向应力平均值与震荡值(最大值一最小值)明显增大."心肌桥-冠状动脉"模拟装置能提供体外研究周向应力对血管影响的实验手段.     

Cell Area and Strut Distribution Changes of Bent Coronary Stents： A Finite Element Analysis

Coronary stents are metal coils or mesh tubes delivered to blocked vessels through catheters, whic Recently, special drugs h are expanded by balloons to reopen and scaffold target vessels. are carried by stents （drug-eluting stents） to further reduce instent restenosis rate after stenting procedure. However, continual study on biomechanical characteristics of stents is necessary provide a more suitable drug loading for better interactions between stents and tissue, or to platform for drug-eluting stents. The purpose of this paper is to show how finite element methods can be used to study cell area and strut distribution changes of bent coronary stents. A same bending deformation was applied to two commercial coronary stent models by a rigid curved vessel. Results show that the stent design influenced the changes of cell area and strut distribution under bending situation. The stent with links had more cell area changes at outer curvature, and the stent with peak-peak （ 〉 〈 ） strut design could have strut contact and overlapping at inner curvature. In conclusion, this finite element method can be used to study and compare cell area and strut distribution changes of bent stents, and to provide a convenient tool for designers in testing and improving biomechanical characteristics of new stents.     

Patient-specific simulations of stenting procedures in coronary bifurcations: Two clinical cases

Computational simulations of stenting procedures in idealized geometries can only provide general guidelines and their use in the patient-specific planning of percutaneous treatments is inadequate. Conversely, image-based patient-specific tools that are able to realistically simulate different interventional options might facilitate clinical decision-making and provide useful insights on the treatment for each individual patient.The aim of this work is the implementation of a patient-specific model that uses image-based reconstructions of coronary bifurcations and is able to replicate real stenting procedures following clinical indications. Two clinical cases are investigated focusing the attention on the open problems of coronary bifurcations and their main treatment, the provisional side branch approach. Image-based reconstructions are created combining the information from conventional coronary angiography and computed tomography angiography while structural finite element models are implemented to replicate the real procedure performed in the patients.First, numerical results show the biomechanical influence of stents deployment in the coronary bifurcations during and after the procedures. In particular, the straightening of the arterial wall and the influence of two overlapping stents on stress fields are investigated here. Results show that a sensible decrease of the vessel tortuosity occurs after stent implantation and that overlapping devices result in an increased stress state of both the artery and the stents. Lastly, the comparison between numerical and image-based post-stenting configurations proved the reliability of such models while replicating stent deployment in coronary arteries.     

A link between stent radial forces and vascular wall remodeling: The discovery of an optimal stent radial force for minimal vessel restenosis

Coronary and peripheral artery disease (PAD) continue to be primary causes of morbidity and mortality in western nations; percutaneous transluminal angioplasty (PTA) with stenting has become a popular treatment. Unfortunately, restenosis is a significant problem following intravascular stent placement. This study considers the contribution of stent forces in vascular stenosis and remodeling to develop an equation for identifying the optimal stent force. z-Type stents of three radial forces [low (3.4 N), high (16.4 N), and ultrahigh (19.4 N)] were deployed into the iliac arteries of a juvenile porcine model. Vessel diameters were measured before, after deployment, and again at 30 days. At 30 days animals were killed and the vessels fixed in situ. After implantation, there was a significant increase in total thickness and neointimal hyperplasia with increasing stent force. The model for vessel radius and experimental data was in agreement. The model shows that maximum late‐term radius is achieved with a stent deployment stress of 480 kPa, which occurs at the end of the stress–strain curve nonlinear domain and beginning of the high-strain collagen domain. The results and calculations suggest that an optimal stent force exists that is subject to the geometry, structure, and mechanics of the target vessel. To achieve maximum late-term dilatation, stents should not produce stress in the vessel wall greater than the end of the transitional domain of the vessel's stress–strain curve. This finding is extremely important for vascular stent development and will be expanded to preliminary vessel wall injury and atherosclerotic models.     

药物洗脱冠状动脉支架系统动物实验研究

目的通过观察在猪动脉中置人心畅可降解聚合物涂层药物洗脱冠状动脉支架（天津百畅公司开发）及对照组支架后的植入后管腔丢失、内皮化、炎症反应、损伤及血栓形成情况来评价国产可降解聚合物涂层药物洗脱支架临床应用的可行性。方法将2种共60枚支架分别置入30头猪冠状动脉的前降支、回旋支以及右冠状动脉。支架植入后的2,5,12,25周,将不同数量的猪处死行组织形态学检查,观察炎症、血栓形成情况和内皮化评价。结果支架置入术后的冠脉通畅,无明显狭窄;支架贴血管内壁良好,血管内腔表面光滑;2种支架均无血栓形成,心畅可降解聚合物涂层药物洗脱支架炎症反应及内皮化与对照组无明显差异,其管腔丢失较对照组轻或无明显差异。结论实验提示心畅可降解聚合物涂层药物洗脱支架置入后有良好的血液相容性,生物性能稳定,支架内表面迅速内皮化,血管有良好的开通率。说明可降解聚合物涂层药物洗脱支架是安全、有效的。     

Carotid artery stenting simulation: from patient-specific images to finite element analysis

The outcome of carotid artery stenting (CAS) depends on a proper selection of patients and devices, requiring dedicated tools able to relate the device features with the target vessel. In the present study, we use finite element analysis to evaluate the performance of three self-expanding stent designs (laser-cut open-cell, laser-cut closed-cell, braided closed-cell) in a carotid artery (CA). We define six stent models considering the three designs in different sizes and configurations (i.e. straight and tapered), evaluating the stress induced in the vessel wall, the lumen gain and the vessel straightening in a patient-specific CA model based on computed angiography tomography (CTA) images. For the considered vascular anatomy and stents, the results suggest that: (i) the laser-cut closed-cell design provides a higher lumen gain; (ii) the impact of the stent configuration and of the stent oversizing is negligible with respect to the lumen gain and relevant with respect to the stress induced in the vessel wall; (iii) stent design, configuration and size have a limited impact on the vessel straightening. The presented numerical model represents a first step towards a quantitative assessment of the relation between a given carotid stent design and a given patient-specific CA anatomy.     

Assessment of tissue prolapse after balloon-expandable stenting: Influence of stent cell geometry

Restenosis is a re-narrowing or blockage of an artery at the same site where treatment, such as a balloon angioplasty or stent procedure, has already taken place. Several clinical trials have shown a significant reduction in the restenosis rates with endovascular stenting. The purpose of stenting is to maintain the arterial lumen open by a scaffolding action that provides radial support. However, stenting can cause a vascular injury during the deployment. Indeed, in-stent restenosis remains a major problem in percutaneous coronary intervention, requiring patients to undergo repeated procedures and surgery. The loading imposed by the deployment of the stent on the artery is involved in the restenosis process. Furthermore, it is well known that the stent design plays a role in the outcome of the stenting interventional procedure. This study compares the mechanical effects of the expansion of five different designs of balloon-expandable stents in a coronary artery by means of numerical models based on the finite element method. An index for the evaluation of the tissue prolapse based on the expanded configuration reached by the stent cells is proposed. The effects of the balloon inflation and deflation are included in the present study. Wall stresses and tissue prolapse of the vessel wall within the stent cells are evaluated and compared among the different stent designs. Results show that the printed area does not predict prolapse, and that the proposed index (PI) does correlate with tissue prolapse.     

Proximal atherosclerotic lesion as a cause of very late stent thrombosis

Very late stent thrombosis is defined as in-stent thrombosis occurring after 1 year of an intra-coronary artery stent placement. Drug eluting stents have lately been criticized for increased reports of very late stent thrombosis. The exact cause of these very late stent thromboses is not clearly understood. Virchow's triad describes the three main factors of thrombus formation to be stasis of blood flow, endothelial injury and hypercoagulability. Based on Virchow's triad, we propose the cause of very late stent thrombosis to be formation of a de novo atherosclerotic lesion in the proximal segment of a stented artery. The de novo atherosclerotic lesion narrows the vessel lumen and causes stasis of blood flow in the distal stent. The de novo lesion can also cause myocardial ischemia creating a prothrombotic environment in the stented region. Stasis of blood flow and prothrombotic environment in the stented region can lead to the formation of very late stent thrombosis. Since atherosclerosis is a dynamic aging process in humans, we propose de novo proximal lesions in the coronary arteries can predispose to very late stent thrombosis.     

The role of vascular calcification in inducing fatigue and fracture of coronary stents

Traditional approaches for in-vitro pulsatile and fatigue testing of endovascular stents do not take into consideration the pathologies of the stented vessel and their associated biomechanical effects. One important pathology is calcification, which may be capable of inducing changes in the vessel wall leading to inhomogeneous distribution of stresses combined with wall motion during the cardiac cycle. These local property changes in the region adjacent to stents could directly influence in-vivo stent performance. Seven cases containing a total of 18 stents were obtained from autopsy. Radiographs were evaluated and vessels were sectioned for histology and stent topographical analysis. Stents were retrieved by chemical removal of surrounding tissue and surfaces were evaluated using 3D digital optical and scanning electron microscopy for biomechanical abrasion and fracture features. Pathologic complications such as restenosis and thrombus formation were assessed from histological sections. Direct evidence of fracture was found in 6 of the 7 cases (in 12 out of 18 stents; 9 drug eluting and 3 bare metal). The degree of stent alterations was variable, where separation of segments due to fracture occurred mostly in drug-eluting stents. All fracture surfaces were representative of a high cycle fatigue mechanism. These fractures occurred in complex lesions involving the presence of diffuse calcification alone, or in combination with vessel angulations and multiple overlapping stents. Morphologic analysis of tissue at or near some fracture sites showed evidence of thrombus formation and/or neointimal tissue growth.     

冠状动脉内药物洗脱支架置入通过困难不同锚定方法的对比

背景：边支球囊锚定和远端钢丝锚定是提高冠状动脉内支架通过到位率的有效办法,目前国内尚无比较上述两种锚定方法在提高支架通过成功率方面的研究。 目的：比较边支球囊锚定和远端钢丝锚定在提高冠状动脉介入治疗药物洗脱支架通过困难方面的临床效果。 方法：纳入87例冠状动脉介入治疗过程中药物洗脱支架通过困难病例,随机分2组治疗,其中46例采用边支球囊锚定方法提高支架通过到位率,41例采用远端钢丝锚定方法提高支架通过到位率。对比两组患者支架置入成功率,以及支架置入12个月内的支架材料生物相容性问题,包括主要不良心脏反应、再发心绞痛、支架再狭窄和晚期管腔丢失等。 结果与结论：远端钢丝锚定组药物洗脱支架置入成功率明显高于边支球囊锚定组(83%,61%,P < 0.05),两组患者药物洗脱支架置入过程中并发症及支架置入12个月内的主要不良心脏反应、再发心绞痛、支架再狭窄和晚期管腔丢失结果比较差异无显著性意义(P > 0.05)。说明远端钢丝球囊锚定方法在不影响支架材料生物相容性的情况下,更有利于提高冠状动脉支架通过率。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

Simulation and experimental observation of contact conditions between stents and artery models

Treatment of coronary artery stenosis with percutaneous coronary angioplasty and stenting is sometimes complicated by neointimal hyperplasia, possibly due to interaction of the stent with the arterial wall within a specific contact area. Therefore, we characterized the stress distribution at the contacts between the stent and the artery using mathematical and experimental modeling (an arterial cylinder model with a tube-like structure and an arterial stenosis model, consisting of a tube and plaque portion) and two kinds of link stents with different numbers of cells and links. First, the contact condition was investigated using a finite element method (FEM). Second, experimental visualization of the contact area between the stent and the artery models was performed. Comparison of the experimental results with the FEM analysis revealed that the contact area between the stent (with a high number of cells and links) and the artery model was distributed over the total surface of the stent. Further, values obtained from the experimental distribution and the calculated distribution were similar. These data indicate that experimental modeling and FEM analysis are useful methods for analyzing the relationship between stent structure and stent/wall stress distributions and may help guide the design of new stents.