Abstracts presented at the Ireland-UK Platelet Conference, 4–6 September, 2005, Dublin,Ireland

In the present report, we describe a unique case of very late stent thrombosis with a bare-metal stent that occurred more than a decade after stent implantation. Potential explanations for the late stent thrombosis are non-compliance to aspirin, late acquired malapposition of the stent, progression of atherosclerosis or in-stent restenosis. In our patient, none of these explanations seems to have played a role. Although the occurrence of (very) late stent thrombosis is not uncommon with drug-eluting stent (DES), it is rather unusual with bare-metal stent (BMS). Nevertheless, cardiologists should be aware of the potential complication of late stent thrombosis, even with bare-metal stents.     

Migration of the AVE micro coronary stent

The AVE Micro coronary stent is a balloon-expandable stent with a design that is different from the commonly used slotted tubular or coil stents. The stent delivery system is low in profile and very trackable so that it can negotiate tortuous vessels to reach distal lesions. It also can pass through proximally deployed stents easily. Its moderate radioopacity allows precise stent placement. However, as illustrated in the three case reports presented here, the stent struts did not seem to be firmly embedded into the arterial wall after initial deployment, so that stent migration occurred during subsequent passage of a balloon into the stent for poststenting high pressure balloon dilatation. This new phenomenon of stent migration has not been reported previously with other stents. © 1996 Wiley-Liss, Inc.     

Clinical applications of a new enhanced stent imaging technology

Enhanced Stent Imaging (ESI) refers to a rapidly evolving class of imaging tools that seek to provide enhanced visualization of coronary stent architecture with minimal disruption to the catheterization laboratory workflow. Various ESI stent platforms are available, all of which utilize a brief cine acquisition of a deflated balloon within a stent to generate a motion‐corrected, enhanced image of the stent. The enhanced image permits detailed assessment of stent architecture, integrity, and positioning relative to other stents. We present two illustrative cases of percutaneous coronary intervention utilizing a new ESI platform. The relevant literature is briefly reviewed.© 2013 Wiley Periodicals, Inc.     

药物洗脱支架血栓形成

支架内血栓形成是支架置入术后少见,但后果严重的并发症,广受关注。支架内血栓形成病因多种多样,包括患者、病变、操作及支架本身等。现对药物涂层支架内血栓形成的相关临床证据和病理生理机制,特别是药物涂层支架本身在其中的作用进行综述。     

冠状动脉支架内血栓与药物洗脱支架的安全性

最近,药物洗脱支架的安全性问题引起了人们的广泛关注。目前资料表明药物洗脱支架与金属裸支架相比并不引起更多的早、晚期支架内血栓发生,但极晚期支架内血栓形成的风险增加。药物洗脱支架明显降低支架内再狭窄的发生和靶病变的再次血运重建率,其有效性仍优于金属裸支架,尤其对于糖尿病等再狭窄高危患者。根据患者的临床具体情况合理选择支架非常重要。现综述冠状动脉支架内血栓与药物洗脱支架安全性的研究进展。     

硅酮支架与覆膜金属支架并发症的对比观察

目的对照观察硅酮支架与Z型不锈钢覆膜金属支架置入后的并发症,为临床支架的选择提供参考。方法 2014年4月至2015年2月因气道狭窄或气道瘘65例患者置入硅酮支架,77例患者置入覆膜金属支架,术后定期支气管镜检查,观察2个月内两组病例的主要并发症。结果硅酮支架组置入分叉型支架45例、沙漏状支架7例、直筒型支架13例;覆膜支架组置入分叉型支架70例、直筒型支架7例。两组并发症比较:痰液潴留硅酮支架50例(76.9%)、覆膜支架61例(79.2%),相差不显著(P0.05);肉芽增生硅酮支架39例(60.0%)、覆膜支架69例(89.6%),相差显著(P0.01);支架移位:分叉型及沙漏状支架均无移位,直筒型支架移位硅酮支架2例(15.3%)、覆膜支架6例(85.7%),相差显著(P0.01);顽固性咳嗽硅酮支架4例(6.1%)、覆膜支架7例(9.0%),相差不显著(P0.05)。因肉芽增生明显经处理效果差,9例覆膜支架取出支架,硅酮支架未因肉芽增生取出支架。结论硅酮支架与覆膜支架比较,硅酮致肉芽增生较轻,其直筒型移位较少,建议对需长期放置支架的患者,优先考虑硅酮支架。     

Duration of balloon inflation for optimal stent deployment: Five Seconds Is Not Enough

Objectives: To assess the effect of the duration of stent inflation on stent expansion using digital stent enhancement (DSE). Background: Optimal stent expansion and apposition to the vessel wall are of critical importance to optimize the results of percutaneous coronary intervention (PCI). However, it is not known if stent inflation duration impacts on stent expansion. Methods: We performed a prospective cohort study in patients undergoing PCI. Quantitative coronary angiography and DSE data were analyzed. DSE was performed at 5, 15, and 25 sec during stent implantation, after target balloon inflation pressure was achieved. Results: One hundred and four consecutive patients (150 lesions) were enrolled. The mean age was 66.9 ± 11.1 years. Complex lesions (ACC/AHA B2/C) occurred in 26.9%. Stents used: Cypher Select (54.1%), Xience V (30.6%), and Taxus Liberté (15.3%). The minimal stent diameter increased significantly with the duration of stent inflation: 2.60 ± 0.51, 2.76 ± 0.51, and 2.82 ± 0.52 mm at 5, 15, and 25 sec (P < 0.0001). Similarly, maximal stent diameter increased with the duration of stent inflation: 3.21 ± 0.51, 3.32 ± 0.52, and 3.36 ± 0.54 mm (P < 0.0001). The average stent diameter also increased with longer stent inflation (P < 0.0001). Using MUSIC criteria 24.0, 53.3, and 68.0% of stents were appropriately expanded at 5, 15, and 25 sec (P < 0.0001).Conclusions: The duration of stent balloon inflation has a significant impact on stent expansion. Stent deployment for >25 sec is recommended. © 2012 Wiley Periodicals, Inc.     

Transcatheter removal of atrial septal stent placed to decompress left atrium with VA ECMO

Left atrial (LA) decompression in infants with thick atrial septum placed on veno‐arterial extracorporeal membrane oxygenation (ECMO) can be reliably achieved with transcatheter atrial septal (AS) stent placement. However, with myocardial recovery and ECMO decannulation the stent causes a permanent left to right shunt and surgical removal of the AS stent is usually accomplished. Transcatheter removal of AS stent is an attractive option as the advantages of LA decompression would then be coupled with the advantage of avoiding a sternotomy for surgical removal of the stent. To our knowledge, this is the first reported case of successful transcatheter retrieval of AS stent used for LA decompression in a 13‐month‐old child. © 2015 Wiley Periodicals, Inc.     

Airway stenting in Japan

Various types of outstanding airway stents have been made commercially available. In Japan, a total of 1004 airway stents (Dumon stents (Novatech, Aubagne, France), Gianturco Z stents (Cook Ins, Bloomington, USA), Ultraflex stents (Boston Scientific Corp, Natick, MA, USA), and Dynamic Y stents (Ruesch AG, Kernen, Germany)) were implanted from July 1991 until February 1998. Of all the various stents, the Dumon stent has become the standard worldwide. Also, the Dumon stent has been replacing the Gianturco Z stent as the preferred stent throughout Japan. The Dumon stent was the first stent covered by Japanese National Health Insurance. Therefore, we present our 5-year experience with the Dumon stent at our institution. In our experience, stenting is effective for the immediate and lasting relief of symptoms in patients with severe malignant obstruction of major airways.     

Vascular endoscopic and macroscopic observations after crush stenting of coronary artery bifurcations in pigs.

The crush stent technique has recently been proposed to limit the development of restenosis between drug-eluting stents implanted at coronary artery bifurcations. We studied the stent expansion, apposition to the vessel, and aspect of the overlapping stents after in vivo crush stent implantation. Crush stent implantation was performed at coronary bifurcations in anesthetized swines. The treated sites were examined using intravascular ultrasound and a vascular endoscope. The stents removed from the vessel were analyzed macroscopically. After final kissing balloon inflation, an adequate apposition of the stent to the vessel wall was confirmed by vascular endoscopy and visual inspection. However, the side-branch stent was narrowed at the site of stent overlap, and the overlapping stents in the main branch created a metal mass, which could promote the development of thrombosis. The technique of crush stent implantation with additional kissing balloon inflation is feasible and promising. However, it may be limited by thrombosis and restenosis at the carina because of stent overlapping and potential incomplete apposition. Additional studies are needed to confirm the safety and long-term clinical results of this technique.     

Efficacy and safety of standard and anti-reflux self-expanding metal stent: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND Self-expanding metal stents are the main palliative treatment modality for unresectable esophageal cancer. Gastroesophageal reflux is a common adverse outcome after placement of esophageal stent for cancer involving the gastroesophageal junction and the gastric cardia. Anti-reflux stents with valve have been designed to prevent the acid reflux. The superiority of anti-reflux stent over standard stent in preventing gastroesophageal reflux has not been established well. This study compares the anti-reflux stent and the standard stent in terms of their efficacy to prevent acid reflux.AIM To compare the standard and the anti-reflux stents in terms of their efficacy,safety, and complications.METHODS The meta-analysis included 8 randomized clinical trials(RCTs) to compare pooled outcomes of total 395 patients. Primary outcomes include improvement in reflux symptoms and dysphagia score. Secondary outcomes include complications of stent migration, occlusion, and bleeding.RESULTS A total of eight RCTs were included in the meta-analysis. Compared to the standard stent, the anti-reflux stent showed a trend towards reduction in the dysphagia score without reaching a statistical significance [Standardized mean difference(SMD):-0.33(-0.71, 0.05); P = 0.09, I2: 37%]. There was no statistical difference in the gastrointestinal reflux(GER) scores between the two types of stents [SMD:-0.17(-0.78, 0.45); P = 0.008, I2: 74%]. Compared to standard stent,anti-reflux stent showed no difference in the risk of stent migration [OR: 1.37(0.66, 2.83); P = 0.40, I2: 0 %], bleeding [OR: 1.43(0.40, 5.13); P = 0.59, I2: 0 %], and obstruction [OR: 1.66(0.60, 4.60); P = 0.33, I2: 0 %].CONCLUSION Traditional self-expanding standard esophageal stent and anti-reflux stent with valve are similar in terms of outcomes and complications.     

New method for placement of intracoronary stents in order to avoid their embolization in the intravascular space

Stent dislodgment from the delivery catheter is a well-known complication of angioplasty with stent implantation. The aim of our study was to investigate the feasibility, effectiveness, and safety of a new technique of intracoronary stent implantation in order to avoid stent loss in the intravascular space. Fifty consecutive patients were candidates for angioplasty and stent placement. During angioplasty, a technique was followed according to which the guide wire “hindered” the dislodgment of the stent from the balloon catheter. Successful angioplasty and stent placement were performed in 46 out of 50 patients (92% success rate). In three cases of failure of stent implantation, the stent moved onto the balloon catheter; however, this was impeded by the guide wire. One non-Q-wave myocardial infarction occurred. No major complications (Q-wave myocardial infarction, CABG, or death) were observed. In conclusion, the technique applied was feasible enough, safe, and effective. However, the appropriate modification of its “hardware” will render it even more feasible and user-friendly. Cathet. Cardiovasc. Diagn. 45:183–187, 1998. © 1998 Wiley-Liss, Inc.     

Drug‐eluting stent fracture: Incidence,contributing factors,and clinical implications

Stent fracture has been observed in noncoronary vessels, especially in the superficial femoral and popliteal arteries and with bare metal stents in saphenous vein grafts of coronary arteries. Since the introduction of drug‐eluting stents, stent fractures have also been reported in small studies and case reports. We reviewed these publications to assess what is known regarding the incidence, contributing factors, and clinical implications of drug‐eluting stent fracture in coronary arteries. The reported rate of drug‐eluting stent fracture in coronary arteries ranges from 1 to 8%, although much of the available literature is derived from single‐center studies that are heterogeneous in their study methods. A higher risk of stent fracture may be associated with the right coronary artery location, excessive tortuosity or angulation of the vessel, overlapping stents, and longer stents. The closed‐cell design of the Cypher stent has been associated with increased rigidity that may increase the risk of stent fracture, although these studies did not assess the overall outcomes between the Cypher and Taxus stents in a head‐to‐head comparison. Stent fracture has been shown by most studies to be associated with a statistically increased incidence of focal in‐stent restenosis, and some have shown an increased risk of target lesion revascularization. Other complications observed with stent fracture include stent thrombosis, coronary aneurysms, myocardial infarction, and sudden death. © 2009 Wiley‐Liss, Inc.     

Unrecoverable stent deformation in the left main: Crush it or remove it?

Serial ostial and distal left main lesions continue to be one of the most difficult tasks for the interventional cardiologist, with many potential complications occurring. We present such a high-risk percutaneous coronary intervention where immediate stent explantation was deemed necessary because the metal deformation and high radial strength of the particular stent platform would prevent an acceptable procedural result if it had been crushed to the vessel wall. The aim of this paper was to discuss left main stent deformation, debate the risks and benefits of stent explantation and finally test in-vitro our theory on “insufficient” crush with stents with high radial strength and compare it with conventional stents. Bench-testing supports our ad-hoc explantation decision showing stent underexpansion, recoil, and malapposition, obtaining an inadequate minimal stent area.     

“Procedural trauma risks longitudinal shortening of the promus element™ stent platform”

This case series raises further awareness of the potential for longitudinal shortening with the Promus Element? (Boston Scientific, MN) drug‐eluting stent (DES) platform. With safety at the forefront of DES development, newer generation systems are utilizing thinner platforms with little or no polymer. Although these contemporary, ultrathin platforms also improve conformability and deliverability, specific design characteristics might inadvertently reduce longitudinal strength. To date, there are no randomized data addressing this issue in vivo for any stent platform, with opinion based on individual experience and bench testing. We report five cases of longitudinal shortening with the Promus Element stent occurring in our institution over a 15‐month period. During the same period, we experienced only isolated cases with other second generation DES platforms. Our experience supports recently published bench‐top data correlating the two‐link design of this platform with the risk of compression. © 2012 Wiley Periodicals, Inc.     

Development of a reexpandable covered stent for children.

The use of covered stents in children is limited by the need for a large long sheath for delivery and the impossibility of redilation once implanted. The authors developed a reexpandable covered stent implantable in children through a small sheath and evaluated its clinical feasibility in mini piglets. An original Palmaz stent was covered with a polyurethane membrane that could be stretched up to 700%. Under general anesthesia, the authors implanted the covered stents in six mini piglets using a long sheath with a diameter approximately 1 French larger than the recommended size required to deliver an uncovered Palmaz stent. The implantation technique was similar to conventional stent implantation. In six piglets, the stent could be redilated from 7.5 to 8.7 mm 28-70 days after implantation. Macroscopic and microscopic examination showed intimal coverage of the coating with minimal inflammatory reaction around the stent. Our newly designed reexpandable stent covered with a polyurethane membrane is promising for use in children.     

PLASTIC STENT PLACEMENT FOR UNRESECTABLE MALIGNANT BILIARY STRICTURE

Background: Endoscopic stent placement is an efficacious treatment for patients with malignant biliary stricture. We investigated the indications for plastic stent placement in patients with unresectable malignant biliary stricture. Patients and methods: Eighty‐three patients with unresectable malignant biliary stricture who had undergone endoscopic placement of either a plastic stent or a covered metal stent in our department between February 1997 and September 2002 were reviewed retrospectively. Results: Metal stents had significantly longer patency (273 ± 99 days) than plastic stents (155 ± 52 days) (P = 0.0292). The two groups showed similar patency curves up to 150 days. Conclusions: The indication for plastic stent placement as palliative therapy for unresectable malignant biliary stricture is drainage for patients with an expected survival of less than 5 months.     

极晚期支架内血栓的研究进展——发病机制及防治策略

药物洗脱支架应用于临床后,支架血栓问题引起广泛关注。目前的研究资料表明药物支架与金属裸支架相比并不引起更多的早、晚期支架内血栓的发生,但极晚期支架血栓形成的风险增加。极晚期支架发生机制复杂,临床多表现为严重的心血管事件,应予以积极防治。现综述极晚期支架内血栓的相关研究进展。     

合理看待药物洗脱支架晚期血栓问题

冠状动脉支架现广泛应用于冠心病的介入治疗中。支架内血栓是金属裸支架和药物洗脱支架的一个并发症,可导致心肌梗死或死亡。最近,药物洗脱支架引起晚期支架内血栓的问题引起人们的广泛关注。支架血栓的危险因素包括操作因素(如支架贴壁不良、置入支架的数目、支架长度及夹层)、患者及病变因素、过早停用抗血小板药物以及支架释放的药物使内皮延迟愈合等。现对支架晚期血栓的概念、发生的危险因素、防治措施等进行探讨。     

Increased incidence of stent thrombosis in patients with cocaine use.

INTRODUCTION: Coronary stent thrombosis is a rare occurrence in the era of dual-antiplatelet therapy. It is not known whether patients who use cocaine have a higher risk of thrombosis following coronary stent placement. METHODS: We studied 247 consecutive patients who underwent coronary stent placement at an inner-city hospital. RESULTS: Twelve patients (4.9%) were actively using cocaine at the time of PCI. Of these twelve patients, four patients presented with stent thrombosis (33%) at a mean of 51 +/- 40 days (median 45 days), after the index revascularization procedure. Only 2 of the 235 patients without documented cocaine use (0.85%) had stent thrombosis during the same period (P < 0.0001). CONCLUSION: The patients who actively use cocaine have a markedly higher risk of stent thrombosis when compared with patients without a documented history of cocaine use. We discuss various factors that potentially predispose cocaine users to stent thrombosis.