冠状动脉内重叠支架置入术的临床研究进展

重叠支架置入术是临床上用来治疗冠状动脉弥漫性长病变的常用方法,以往曾采取重叠裸金属支架置入术,但其临床预后不佳,目前较为常用的重叠药物洗脱支架置入术被认为相对安全、有效,但仍存在许多潜在问题。本文介绍了适合使用重叠支架置入术进行治疗的冠状动脉病变的特点,回顾了重叠裸金属支架的临床应用情况,阐述了近年来药物洗脱支架的发展以及重叠药物洗脱支架置入术的优势,比较了四种负载不同药物的药物洗脱支架同种重叠置入后的临床疗效,观察了异种药物洗脱支架混合重叠置入后的临床特点和支架重叠段对临床预后的影响,分析了重叠支架置入术与几种其它治疗冠状动脉弥漫性长病变方法的应用区别,并对新一代药物支架的重叠应用进行了展望。     

A new stent with streamlined cross-section can suppress monocyte cell adhesion in the flow disturbance zones of the endovascular stent

We proposed a new stent with streamlined cross-sectional wires, which is different from the clinical coronary stents with square or round cross-sections. We believe the new stent might have better hemodynamic performance than the clinical metal stents. To test the hypothesis, we designed an experimental study to compare the performance of the new stent with the clinical stents in terms of monocyte (U-937 cells) adhesion. The results showed that when compared with the clinical stents, the adhesion of U-937 cells were much less in the new stent. The results also showed that, when Reynolds number increased from 180 (the rest condition for the coronary arteries) to 360 (the strenuous exercise condition for the coronary arteries), the flow disturbance zones in the clinical stents became larger, while they became smaller with the new stent. The present experimental study therefore suggests that the optimization of the cross-sectional shape of stent wires ought to be taken into consideration in the design of endovascular stents.     

Simulation of stent deployment in a realistic human coronary artery

Background  

The process of restenosis after a stenting procedure is related to local biomechanical environment. Arterial wall stresses caused by the interaction of the stent with the vascular wall and possibly stress induced stent strut fracture are two important parameters. The knowledge of these parameters after stent deployment in a patient derived 3D reconstruction of a diseased coronary artery might give insights in the understanding of the process of restenosis.     

Finite element analysis of the biomechanical interaction between coronary sinus and proximal anchoring stent in coronary sinus annuloplasty

Recent clinical studies of the percutaneous transvenous mitral annuloplasty (PTMA) devices have shown a short-term reduction of mitral regurgitation after implantation. However, adverse events associated with the devices such as compression and perforation of vessel branches, device migration and fracture were reported. In this study, a finite element analysis was carried out to investigate the biomechanical interaction between the proximal anchor stent of a PTMA device and the coronary sinus (CS) vessel in three steps including: (i) the stent release and contact with the CS wall, (ii) the axial pull t the stent connector and (iii) the pressure inflation of the vessel wall. To investigate the impact of the material properties of tissues and stents on the interactive responses, the CS vessel was modelled with human and porcine material properties, and the proximal stent was modelled with two different Nitinol materials with one being stiffer than the other. The results indicated that the vessel wall stresses and contact forces imposed by the stents were much higher in the human model than the porcine model. However, the mechanical differences induced by the two stent types were relatively small. The softer stent exhibited a better fatigue safety factor when deployed in the human model than in the porcine model. These results underscored the importance of the CS tissue mechanical properties. Vessel wall stress and stent radial force obtained in the human model were higher than those obtained in the porcine model, which also brought up questions as to the validity of using the porcine model to assess device mechanical function. The quantification of these biomechanical interactions can offer scientific insight into the development and optimisation of the PTMA device design.     

Immediate and long-term outcomes of coronary stenting in relation to stent implantation pressure in patients with coronary heart disease

The paper evaluates the pressure impact of implantation of intracoronary stents of different designs on the immediate and long-term outcomes of stenting. A retrospective study included 192 patients. Matrix and wire stents were implanted in 97 (50.5%) and 95 (49.5%) patients, respectively. In one part of the patients, the coronary stent was implanted under nominal pressure, in the other, the stent after implantation was extended with a balloon by using high pressure. Good immediate angiographic and clinical results were obtained in all 192 patients. Thirty three (17.2%) patients were found to have coronary spasm at the site of a stent. There was no significant difference in the development of coronary spasm, which was associated with the type of an implanted (matrix or wire) stent and with the pattern of its implantation (under high or nominal pressure). Dissection along the stent edges developed in 17 of the 192 patients, which amounted to 8.8%. It significantly more frequently developed in patients from Subgroup IA than in those from Subgroup IB. There was no significant difference in the development of restenosis in patients after implantation of matrix or wire stents and in the relation to the stent implantation pressure.     

Impact of Coronary Artery Curvature on the Longitudinal Stent Foreshortening: Real-World Observations

Longitudinal stent foreshortening is a known phenomenon, however, the impact of coronary artery curvature on longitudinal stent foreshortening remains unclear. The aim of this study is to determine the impact of coronary artery curvature on the longitudinal stent foreshortening in the real-world scenarios. A total of 86 consecutive patients underwent coronary stent implantation were included in the present study. The degree of coronary artery curvature was defined as the length of the coronary artery curvature divided by the straight length. Longitudinal stent foreshortening was defined as the stent length after implantation divided by the stent length before implantation. The mean longitudinal foreshortening rate of coronary stents was about 94% in curved coronary arteries. Longitudinal stent foreshortening rate was positively correlated with the degree of coronary artery curvature (r = –0.86, P < 0.01). Coronary artery curvature is associated with significant longitudinal foreshortening of coronary stents, thus longitudinal foreshortening should be considered on deciding the stent length in curved coronary artery and a longer stent is usually needed in curved coronary artery.     

Provisional stenting in small vessels

Based on the currently available data, the strategy of routine stent placement in unselected lesions located in small coronary arteries provides good immediate results but is still associated with a high incidence of in-stent restenosis. Randomized trials comparing elective stenting with balloon angioplasty have not provided the demonstration that routine stenting is the best strategy for percutaneous intervention in coronary arteries with a reference diameter smaller than 2.75-3.0 mm. This paper describes the rationale for provisional stenting in this clinical setting and reviews the role of quantitative coronary angiography, intracoronary ultrasound and intracoronary Doppler measurements in the identification of lesions that would benefit from adjunctive stent placement after balloon angioplasty and in guiding stent implantation.     

Clinical outcomes of long coronary stents: a single-center experience

BACKGROUND: Coronary artery stenting is particularly useful during percutaneous coronary intervention for long lesions previously associated with a low procedural success rate and a high complication rate of dissection and occlusion. Current treatment options include implantation of a single long stent, multiple contiguous stents, or 'spot' stenting. However, multiple stent implantation may result in sections of overlapping stent or gaps of unstented segments and is an independent predictor of restenosis. The early and intermediate clinical outcome of single and multiple long stent (>/= 30 mm) implantation is not established. METHODS AND RESULTS: The authors retrospectively identified 123 consecutive patients who had undergone stenting using one or more long coronary stents. Baseline clinical data, procedural outcomes and completed clinical follow-up to 52 weeks were obtained by case-note review. The majority (69%) required intervention for stable coronary disease. Seventy-seven per cent of lesions were either type B2 or C and only 2% were in saphenous vein grafts. The procedural success rate was 94%. A total of 15 major events occurred in 13 patients (11%). Ten acute events occurred and five events were during the follow-up period from 30 days to 52 weeks. Two patients died, one from uncontrolled bleeding secondary to the use of antithrombotic agents and one at four weeks due to sudden death. One patient had a postprocedural infarct. Two patients required in-hospital repeat revascularization for acute vessel closure and eight required revascularization during follow-up (three cases of occlusion/thrombosis and five cases of restenosis). CONCLUSIONS: The use of long coronary stents (>/= 30 mm) for the treatment of long diffuse native vessel disease, saphenous vein graft disease and long coronary dissections is associated with a reasonable procedural success rate and acceptable early and intermediate-term clinical outcomes.     

A cluster randomised controlled trial of the community effectiveness of two interventions in rural Malawi to improve health care and to reduce maternal, newborn and infant mortality

Background

Paclitaxel-eluting stents decrease angiographic and clinical restenosis following percutaneous coronary intervention compared to bare metal stents. TAXUS Element is a third-generation paclitaxel-eluting stent which incorporates a novel, thinner-strut, platinum-enriched metal alloy platform. The stent is intended to have enhanced radiopacity and improved deliverability compared to other paclitaxel-eluting stents. The safety and efficacy of the TAXUS Element stent are being evaluated in the pivotal PERSEUS clinical trials.

Methods/Design

The PERSEUS trials include two parallel studies of the TAXUS Element stent in single, de novo coronary atherosclerotic lesions. The PERSEUS Workhorse study is a prospective, randomized (3:1), single-blind, non-inferiority trial in subjects with lesion length ≤28 mm and vessel diameter ≥2.75 mm to ≤4.0 mm which compares TAXUS Element to the TAXUS Express² paclitaxel-eluting stent system. The Workhorse study employs a novel Bayesian statistical approach that uses prior information to limit the number of study subjects exposed to the investigational device and thus provide a safer and more efficient analysis of the TAXUS Element stent. PERSEUS Small Vessel is a prospective, single-arm, superiority trial in subjects with lesion length ≤20 mm and vessel diameter ≥2.25 mm to <2.75 mm that compares TAXUS Element with a matched historical bare metal Express stent control.

Discussion

The TAXUS PERSEUS clinical trial program uses a novel statistical approach to evaluate whether design and metal alloy iterations in the TAXUS Element stent platform provide comparable safety and improved procedural performance compared to the previous generation Express stent. PERSEUS trial enrollment is complete and primary endpoint data are expected in 2010. PERSEUS Workhorse and Small Vessel are registered at http://www.clinicaltrials.gov, identification numbers NCT00484315 and NCT00489541.     

Why and how to avoid stenting during brachytherapy

Intracoronary radiation is a promising therapy to reduce restenosis after percutaneous coronary intervention. It may be anticipated that radiation and intracoronary stents - the current standard coronary revascularization procedure - have a synergic antirestenosis effect. However, this potential benefit has not been proven in the clinical scenario. Indeed, this combined approach (stenting plus brachytherapy) may even be harmful. Delayed endothelialization and late stent malapposition are important drawbacks of implanting a metallic prosthesis in the setting of radiation therapy. Owing to the relatively high frequency of late thrombosis after stenting irradiated coronary arteries, the Food and Drug Administration required that the labeling of both gamma- and beta-radiation devices recently approved for clinical use explicitly advise avoidance of the placement of new stents. The pathophysiologic aspects as well as the clinical implications of the implantation of a new stent in association with radiation delivered by radioactive stents or catheter-based systems are discussed in this paper.     

血栓弹力图指导支架内血栓后不稳定心绞痛治疗1 例及文献复习

目的:探讨在血栓弹力图监测血小板抑制率的情况下,调整氯吡格雷及阿司匹林用量,治疗冠心病、PCI术后支架内再发血栓患者的临床意义。方法:报告中国人民解放军总医院1例支架内亚急性血栓患者的临床资料并复习相关文献,对其临床表现、诊断、在血栓弹力图指导下的治疗进行分析。结果:1例支架内亚急性血栓患者经治疗病情好转出院,出院后继续调整氯吡格雷及阿司匹林用量,达到满意血小板抑制率,患者症状消失。结论:冠状动脉介入治疗后发生支架内血栓的患者,应用血栓弹力图指导氯吡格雷及阿司匹林用量,可达到令人满意的血小板抑制率,并防止出血情况发生。     

可降解冠状动脉支架的研究进展

冠脉内支架植入是临床上预防PTCA术后再狭窄并发症的有效措施,但金属支架仅在植入早期发生作用,在冠脉内壁修复完成后则成为多余的负担,可能激活血小板及多种凝血因子聚集导致血栓形成及刺激血管壁造成心脏事件及再狭窄的发生。针对上述问题,生物可降解冠状动脉支架的研究得到了相当的发展。本文就可降解支架的发展及现状作一简要综述。     

冠状动脉支架植入术后高凝状态的研究进展

支架内血栓形成是冠状动脉支架植入术后的重要并发症之一,尽管发生率较低,但严重者可危及生命。冠心病支架植入术后高凝状态源自患者的自身因素及支架植入所导致的一系列病理生理反应,包括斑块破裂、血管内皮损伤、组织因子大量表达、微粒生成增多等,进一步可激活血细胞和凝血系统,重者可导致局部血栓形成。及时检测及防治支架术后的高凝状态对降低支架内血栓的发生率有积极作用。本文主要对冠状动脉支架植入术后高凝状态的研究进展进行了综述。     

Palmaz-Schatz stent embolization: long-term clinical and angiographic follow-up

A long-term clinical and angiographic follow-up of a case of peripheral coronary stent embolization is reported. No clinical sequelae occurred in the immediate and long-term (five years) followup. The five-year follow-up angiographic images provided visual documentation of absence of stent-associated stenosis. This case highlights the concept that fibro-intimal hyperplasia may not occur when plaque and balloon trauma are absent at the site of stent embolization.     

An ovine in vivo framework for tracheobronchial stent analysis

Tracheobronchial stents are most commonly used to restore patency to airways stenosed by tumour growth. Currently all tracheobronchial stents are associated with complications such as stent migration, granulation tissue formation, mucous plugging and stent strut fracture. The present work develops a computational framework to evaluate tracheobronchial stent designs in vivo. Pressurised computed tomography is used to create a biomechanical lung model which takes into account the in vivo stress state, global lung deformation and local loading from pressure variation. Stent interaction with the airway is then evaluated for a number of loading conditions including normal breathing, coughing and ventilation. Results of the analysis indicate that three of the major complications associated with tracheobronchial stents can potentially be analysed with this framework, which can be readily applied to the human case. Airway deformation caused by lung motion is shown to have a significant effect on stent mechanical performance, including implications for stent migration, granulation formation and stent fracture.     

血管内超声在冠脉复杂病变介入诊疗中的临床价值

目的:研究血管内超声在冠脉复杂病变介入诊疗中的临床价值。方法:30例确诊为冠心病的患者,其中男性23例,女性7例,先采用冠脉造影(CAG),选择美国心脏病学会和美国心脏病协会(ACC/AHA)推荐的冠脉分型C型中弥漫性病变(>20mm)、近端血管过度扭曲病变,然后行IVUS检查,PCI术后再行IVUS检查,比较两者及PCI前后IVUS结果的差异。结果:CAG示支架贴壁良好,再行IVUS检查示支架贴壁不良率达78.4%,IVUS观察均达到支架置入理想标准。结论:IVUS在评价支架贴壁情况、选择高压球囊后扩张时,有着更明显的优势。     

Adrenomedullin expression in coronary circulation after stent implantation as a prognostic factor for restenosis

The authors determined the changes in adrenomedullin (AM) expression in the coronary circulation of patients with ischemic heart disease who underwent coronary stent implantation. Blood samples were drawn from the coronary sinus before, immediately after and four hours after coronary stent implantation, and plasma levels of AM were measured. AM levels in the coronary sinus blood were significantly increased four hours after stent implantation. On the other hand, in the femoral arterial blood, no significant changes in AM levels were observed. A significant positive correlation was found between AM level in the coronary sinus blood four hours after stent implantation and late loss index six months after the procedure. These results suggest that inflammation after coronary stent implantation induces AM expression, which might play an important role in restenosis after stenting.     

Yttrium-90 delivered via a centering catheter and afterloader, given both before and after stent implantation, inhibits neointima formation in porcine coronary arteries

Background: Intracoronary radiation (IR) studies have shown reduction of neointima formation (NF). Extrapolation of animal studies with beta-radiation to clinical trials have shown variable results, which may be related to dosimetry, centering issues, and/or shielding of beta-rays by the stent metal. We examined the effect of yttrium-90 (90Y), a pure beta-emitter delivered via an automatic afterloader to a centering catheter, on the inhibition of NF in balloon-injured (BI) porcine coronary arteries as well as in arteries receiving 90Y either prior to or following stent implantation (SI).Methods: Twenty-three swine (44 coronary arteries) were studied. In the first study, IR (18 Gy at 1.2 mm from the balloon surface) was administered in 17 arteries following BI, while eight control arteries were subjected to BI only. In the second study, 10 swine (19 coronary arteries) underwent SI. IR (18 Gy) was administered in six arteries before and in eight arteries after SI, while five control arteries received SI only. The animals were sacrificed 2 weeks after BI and 4 weeks after SI. Their coronaries were perfusion fixed and stained, and vessel parameters (intimal area [IA] and medial fracture length [FL]) were analyzed by computer-aided histomorphometry.Results: Arteries subjected to IR following BI had less NF compared to controls (IA/FL=0.14+/-0.2 mm vs. 0.49+/-0.2 mm; P=0.003). IA was reduced significantly in the arteries receiving radiation before and after SI compared to controls (0.92+/-0.98 and 0.00+/-0/00 vs. 2.72+/-1.2 mm(2); P=0.014), despite similar SI in all groups.Conclusions: IR with 90Y delivered via a centering catheter is safe and effective with complete and homogenous inhibition of NF in the context of BI or SI in the porcine coronary model.     

GPU-Accelerated Framework for Intracoronary Optical Coherence Tomography Imaging at the Push of a Button

Frequency domain optical coherence tomography (FD-OCT) has become one of the important clinical tools for intracoronary imaging to diagnose and monitor coronary artery disease, which has been one of the leading causes of death. To help more accurate diagnosis and monitoring of the disease, many researchers have recently worked on visualization of various coronary microscopic features including stent struts by constructing three-dimensional (3D) volumetric rendering from series of cross-sectional intracoronary FD-OCT images. In this paper, we present the first, to our knowledge, "push-of-a-button" graphics processing unit (GPU)-accelerated framework for intracoronary OCT imaging. Our framework visualizes 3D microstructures of the vessel wall with stent struts from raw binary OCT data acquired by the system digitizer as one seamless process. The framework reports the state-of-the-art performance; from raw OCT data, it takes 4.7 seconds to provide 3D visualization of a 5-cm-long coronary artery (of size 1600 samples x 1024 A-lines x 260 frames) with stent struts and detection of malapposition automatically at the single push of a button.     

Use of "Cypher" sirolimus-eluting stents in coronary heart disease patients with different types of coronary arterial lesions

The purpose of our study was to assess the immediate and late results of treatment with Cypher drug-eluting stents (Cordis, Johnson & Johnson, USA) in patients with coronary heart disease (CHD). This was a prospective study that included 738 patients who had been implanted Cypher stents in May 2002 to March 2006. The patients' mean age was 56 +/- 9 years; there were 87% of males. The patients were randomly included into the study and they underwent coronary stenting in the routine laboratory setting. A control group comprised 162 patients who had undergone Velocity or Sonic nondrug-eluting stents of the same firm, which had the similar structure. The groups did not differ in clinical characteristics. 827 stenoses in the eluting stent group and 225 stenoses in the control group were subject to revascularization. The immediate cure rate was 95 and 94%, respectively. The total number of events (myocardial infarction, emergency coronary bypass surgery, subacute occlusion of a stented segment) was 2.3% in the eluting stent group and 2.4% in the control group. A repeated examination 1 year after surgery was made in 482 and 119 patients in the drug-eluting and nondrug-eluting groups, respectively. During the follow-up, one patient died of a extracardiac cause and 3 (0.6%) patients underwent coronary bypass surgery in the nondrug-eluting stent group; there were no deaths and 2 (1.6%) patients had coronary bypass surgery in the control group. In the eluting stent group, there were fewer cases of repeated endovascular procedures of target stenosis revascularization than in the control group (3.7% versus 11.7%; p < 0.0005). In the eluting stent group, the total number of unfavorable cardiovascular events was significantly less than that in the control group and it amounted to 3.3% as compared with 15.9% in the non-eluting stent group; p < 0.0005. Cardiovascular event-free survival was significantly higher in the eluting stent group: 92% versus 77% in the non-eluting stent group (p < 0.0005).