塑料胆道支架引流术治疗复杂性胆总管结石的临床研究

目的:探讨内镜下逆行胰胆管造影术(ERCP)下塑料胆道支架引流术治疗复杂性胆总管结石的临床疗效和安全性。方法:回顾性分析2011年9月至2013年9月在我院经ERCP下胆道支架引流术治疗的32例复杂性胆总管结石患者的临床病例资料。结果:32例患者塑料胆道支架引流术全部成功,平均手术时间15-30分钟。术后,2例发生高淀粉酶血症,经禁食72小时后恢复正常,无穿孔、消化道大出血等ERCP严重并发症发生。术后1周,患者腹痛、发热消失,转氨酶及胆红素水平明显下降,平均住院时间6-15天。3个月复查B超,发现结石缩小19例,结石碎裂1例,支架脱落1例。术后7天、术后3个月的肝功能指标与术前比较均显著改善,差异均有统计学意义(P0.05)。结论:ERCP下塑料胆道支架引流术是一种复杂性胆总管结石安全有效的治疗方法,具有创伤小、风险较低、操作时间短、患者易耐受及手术成功率高等优点。     

Drug-eluting stents in the treatment of proximal vertebral artery stenosis

The objective of the study was to evaluate the efficacy of endovascular revascularization treatment using drug-eluting stents in patients with atherosclerotic proximal vertebral artery (VA) stenosis. Thirty-two patients (61 ± 10 years old) were implanted with 35 sirolimus and tacrolimus eluting stents (3 patients had them from two sides). 27 patients (84%) had vertebrobasilar symptoms at enrollment. All patients were pretreated with dual antiplatelet therapy. The intervention was technically successful in 89% cases. No stroke, myocardial infarction, or death occurred in perioperative period. On duplex scanning the stents remained completely functional. In the late postoperative period 29 (91%) patients, with 32 implanted stents were followed- up. The mean follow-up was 9.5 months. No stroke occurred in patients during this period. Recurrence of vertebrobasilar insufficiency symptoms was noted in 3 patients. VA renarrowing was detected in 16 (50%) arteries in 15 patients, and 12 (80%) of them were asymptomatic. Restenosis ≥50% (n = 13) and reocclusion (n = 3) were more frequent in those with implantation of tacrolimus eluting stents compared to those with sirolimus eluting stents: 10 (71%) of 14 observations to 6 (33%) of 18 cases (p = 0.1794), respectively. Stent fracture was observed in 2 cases (6%), followed by restenosis. Restenosis rate prevailed in men (p = 0.0173). Thus, stenting of VA extracranial portion is reasonably safe procedure with a good clinical effect. The use of drug-eluting stents looks promising but does not solve the problem of high restenosis rate in the late postoperative period.     

Bacterial biofilm and clogging of biliary stents

Endoscopic biliary stenting has become a standard palliative treatment for obstructive jaundice due to malignancies of the pancreas and the hepatobiliary system. Despite the high initial success rate in achieving biliary drainage, durable endoscopic stenting has been limited by the clogging of biliary stents, usually after 4–5 months, due to formation of an adherent bacterial biofilm. Various methods have been investigated for the prevention of bacterial adhesion and prolongation of stent patency. These include: 1) prophylactic use of antimicrobial agents and bile salts; 2) testing of new stent material and new designs for these biliary stents; and 3) the recent introduction of self-expandable metal stents. Each method has its own merits as well as specific problems. This article reviews the pathogenesis of biofilm formation on the biliary stents and the latest status of research in avoiding the problem of stent occlusion.     

胆道支架置入联合介入化疗对恶性胆道梗阻患者肝功能及预后的影响

目的:研究胆道支架置入联合介入化疗对恶性胆道梗阻患者肝功能及预后的影响,为临床治疗提供依据。方法:选取2013年2月到2015年2月我院收治的恶性胆道梗阻患者90例,按照随机数字表法将患者分为Ⅰ组、Ⅱ组和Ⅲ组,每组30例,Ⅰ组给予胆道支架置入联合介入化疗,Ⅱ组给予单纯胆道支架置入,Ⅲ组给予保守治疗,比较三组治疗前、后肝功能、并发症、支架通畅率及生存期。结果:治疗前三组谷草转氨酶(AST)、谷丙转氨酶(ALT)、γ-谷氨酰转移酶(r-GT)比较无统计学意义(P0.05),治疗后Ⅰ组和Ⅱ组AST、ALT和r-GT均显著改善,与治疗前和Ⅲ组比较差异具有统计学意义(P0.05),且I组显著优于Ⅱ组,比较差异具有统计学意义(P0.05),Ⅲ组治疗后AST、ALT和r-GT与治疗前比较差异无统计学意义(P0.05);Ⅰ组、Ⅱ组和Ⅲ组并发症发生率比较无统计学意义(P0.05);Ⅰ组术后3个月、6个月和12个月支架通畅率均显著高于Ⅱ组,比较差异具有统计学意义(P0.05);I组生存期显著高于Ⅱ组和Ⅲ组,Ⅱ组高于Ⅲ组,比较差异具有统计学意义(P0.05)。结论:胆道支架置入联合介入化疗治疗恶性胆道梗阻具有较好效果,能明显改善患者肝功,延长患者生存期。     

Clinical and quantitative angiographic outcomes following elective implantation of the self-expanding Wallstent for longer coronary artery lesions--final results of the Wellstent native study

BACKGROUND: Implantation of short balloon-expandable stents provides superior clinical and angiographic outcome compared with balloon angioplasty in selected patients. The purpose of the Wellstent study was to evaluate the safety and efficacy of the self-expanding Wallstent combined with aspirin and ticlopidine in patients with stable or unstable angina related to a native coronary lesion up to 45 mm in length. METHODS: 105 patients (111 lesions) with stable (57%) or unstable (43%) angina were included in this prospective multicentre evaluation. Angiography before and after Wallstent implantation and at 6-month follow-up was analysed at the core lab using the CAAS 2 system. The primary end-point was incidence of major adverse cardiac events (MACE) at 30 days. Secondary end-points were angiographic outcome at 6 months and MACE at 6 months and 1 year. RESULTS: Acute procedural success (successful stent implantation with residual stenosis <20%) was achieved in 99%. Mean reference diameter was 3.18 +/- 0.66 mm, minimal luminal diameter was 1.00 +/- 0.50 mm pre- and 2.84 +/- 0.47 mm poststent (diameter stenosis 16 +/- 6%). The mean hospital stay was 2.2 days. At 30 days, 95% of patients were free of MACE. At 6 month and 1 year clinical follow-up, 75% and 71% of patients, respectively, remained free of MACE, the majority of which (19 of 30) were re-interventions at re-angiography. In 90% of eligible patients, MLD at follow-up was 1.65 +/- 0.75 mm (late loss 1.20 +/- 0.66 mm, loss index 0.66), diameter stenosis 42 +/- 15%, with a restenosis rate of 32%. Longer stents were associated with greater luminal loss (P = 0.001) and less-favourable clinical outcome. CONCLUSIONS: Wallstent implantation, combined with aspirin and ticlopidine, achieved excellent acute and 30 day clinical results in a heterogenous high-risk patient group. Clinical outcome at 6 months and 1 year remained good, and most adverse events were re-PTCA during follow-up angiography. The loss index of 0.66 and restenosis rate of 32%, related in part to the use of longer stents, emphasizes the continuing need for effective anti-proliferative therapy.     

In-stent restenosis after revascularization of myocardium with drug-eluting stents is accompanied by elevated level of blood plasma eosinophil cationic protein

The aim of this study was to assess the involvement of eosinophil cationic protein, a marker of eosinophil activation, in the development of in-stent restenosis after drug-eluting stent implantation. Follow-up angiography at 6 to 12?months was performed in 32 patients who were treated with percutaneous coronary intervention and implantation of sirolimus-eluting stents. Blood plasma levels of eosinophil cationic protein (ECP) and total immunoglobulin E (IgE) were measured by enzyme-linked immunosorbent assay and the level of C-reactive protein (hs-CRP) by high-sensitivity nephelometry. According to angiography data, in-stent restenosis occurred in 13 patients, while 19 patients did not develop it. There were no differences between the hs-CRP and IgE levels in patients with or without restenosis. In contrast, ECP level was higher in patients with restenosis compared with that in patients without restenosis [17.7?ng/mL (11.2-24.0) vs. 9.0?ng/mL (6.4-12.9), p?= 0.017]. The incidence of in-stent restenoses was 63% in patients with ECP level higher than or equal to 11?ng/mL, and 19% in patients with an ECP level lower than 11?ng/mL (p?= 0.019). These findings suggest that elevated eosinophil activation may play an important role in the pathogenesis of in-stent restenosis after implantation of drug-eluting stents.     

Long-term results of chronic occlusion recanalization in patients with coronary heart disease

The study was undertaken to assess the long-term results of recanalization of chronically occluded coronary arteries, by applying drug-eluting stents to patients with coronary heart disease. The study enrolled 585 patients with one-vessel occlusive lesion of one of three great coronary arteries (TIMI 0; occlusion duration, > or = 3 months): 321 patients who underwent successful recanalization of chronic occlusion and further implantation of drug-eluting stents and 264 patients who received drug therapy (a control group). The short- and long-term results of recanalization were investigated. The follow-up averaged 1095 +/- 36 days; reexaminations were made after 1, 2, and 3 years. The direct success rate of recanalization of chronically occluded coronary arteries was 84.9% (321/378). The results of a 3-year follow-up showed the efficiency and expediency of endovascular recanalization of chronic occlusions: the invasively treated patients had the symptoms of angina pectoris and heart failure significantly less frequently, showed higher exercise tolerance and a less need for antianginal therapy, and had a better long-term prognosis.     

内镜下逆行胰胆管造影置放胆道支架治疗恶性梗阻性 黄疸98 例疗效分析

目的:探讨内镜下逆行胰胆管造影置放胆道支架对恶性胆道梗阻的疗效及并发症的防治。方法:选择2008年2月至2011年9月我院收治的无法手术切除或不愿手术的恶性胆道梗阻患者98例,通过放置内置支架引流观察其操作成功率、支架通畅期和退黄效果、并发症发生情况及其防治效果和患者生存期等。结果:98例患者中有88例成功通过置入胆道内置引流管,成功率为89.8%,并发症发生率为11.22%,所有成功患者术后1周黄疸明显减退,支架平均通畅期137天,患者平均生存期为163天。结论:行胆道内置支架引流创伤小,并发症少,通畅性能好,可持久有效地控制黄疸,有效缓解病情,改善全身情况,明显延长恶性胆道梗阻患者的生存期。     

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.     

Endoscopic Treatment of Biliary Stenosis in Patients with Alveolar Echinococcosis – Report of 7 Consecutive Patients with Serial ERC Approach

Background and Aims

Biliary vessel pathology due to alveolar echicococcosis (AE) results in variable combinations of stenosis, necrosis and inflammation. Modern management strategies for patients with cholestasis are desperately needed. The aim is proof of principle of serial ERC (endoscopic retrograde cholangiography) balloon dilation for AE biliary pathology.

Methods

Retrospective case series of seven consecutive patients with AE-associated biliary pathology and ERC treatment in an interdisciplinary endoscopy unit at a University Hospital which hosts a national echinococcosis treatment center. The AE patient cohort consists of 106 patients with AE of the liver of which 13 presented with cholestasis. 6/13 received bilio-digestive anastomosis and 7/13 patients were treated by ERC and are reported here. Biliary stricture balloon dilation was performed with 18-Fr balloons at the initial and with 24-Fr balloons at subsequent interventions. If indicated 10 Fr plastic stents were placed.

Results

Six patients were treated by repeated balloon dilation and stenting, one by stenting only. After an acute phase of 6 months with repeated balloon dilation, three patients showed “sustained clinical success” and four patients “assisted therapeutic success,” of which one has not yet reached the six month endpoint. In one patient, sustained success could not be achieved despite repeated insertion of plastic stents and balloon dilation, but with temporary insertion of a fully covered self-expanding metal stent (FCSEMS). There was no loss to follow up. No major complications were observed.

Conclusions

Serial endoscopic dilation is a standard tool in the treatment of benign biliary strictures. Serial endoscopic intervention with balloon dilation combined with benzimidazole treatment can re-establish and maintain biliary duct patency in AE associated pathology and probably contributes to avoid or postpone bilio-digestive anastomosis. This approach is in accordance with current ERC guidelines and is minimally disruptive for patients.     

Long-term results of implantation of bioengineered and drug-eluting stents in patients with coronary heart disease: comparative characteristics of predictors of poor prognosis

The purpose of the investigation was to study the morphological and clinical characteristics affecting the long-term prognosis after implantation of bioengineered and drug-eluting stents in patients with coronary heart disease (CHD). The investigation covered 2362 patients with CHD. Genous bioengineered stents were implanted in 316 patients; Cypher rapamycin-eluting stents were in 2046 patients. The independent poor factor for complications was discontinuation of antiaggregatory therapy due to surgical interventions of different types in the drug-eluting stent group and stenting of extensive stenoses in the bioengineered stent group.     

Intraductal Radiofrequency Ablation Followed by Locoregional Tumor Treatments for Treating Occluded Biliary Stents in Non-Resectable Malignant Biliary Obstruction: A Single-Institution Experience

Objectives

To determine the safety and feasibility of intraductal radiofrequency ablation (RFA) followed by locoregional tumor treatments in patients with non-resectable malignant biliary obstruction and stent re-occlusion.

Methods

Fourteen patients with malignant biliary obstruction and blocked metal stents were studied retrospectively. All had intraductal RFA followed by locoregional tumor treatments and were monitored clinically and radiologically. The practicality, safety, postoperative complications, jaundice remission, stent patency and survival time were analyzed.

Results

Combination treatment was successful for all patients. There were no severe complications during RFA or local treatments. All patients had stent patency restored, with a decline in serum bilirubin. Three patients had recurrent jaundice by 195, 237 and 357 days; two patients underwent repeat intraductal RFA; and one required an internal-external biliary drain. The average stent patency time was 234 days (range 187-544 days). With a median follow-up of 384 days (range 187-544 days), six patients were alive, while eight had died. There was no mortality at 30 days. The 3, 6, 12 and 18 month survival rates were 100%, 100%, 64.3% and 42.9%, respectively.

Conclusion

Intraductal RFA followed by locoregional tumor treatments for occluded metal stents is safe and practically feasible and potential increase stent patency and survival times.     

Malignant Ureteral Obstruction: Functional Duration of Metallic versus Polymeric Ureteral Stents

Background

Ureteral obstruction caused by extrinsic compression is often associated with intra-abdominal cancers. Internal drainage with ureteral stents is typically the first-line therapy to relieve such obstructions. Novel designs of ureteral stents made of different materials have been invented to achieve better drainage. In this study, we described the functional outcomes of a Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA) in patients with malignant ureteral obstruction and compare the functional duration of Resonance stents with regular polymeric stents in the same cohort.

Methods

Cancer patients who received polymeric stents and subsequent Resonance stents for ureteral obstruction between July 2009 and November 2012 were included in a chart review. Stent failure was detected by clinical symptoms, imaging studies, and renal function tests. The functional durations of each stent were calculated, and possible factors affecting stent patency were investigated.

Results

A total of 50 stents were successfully inserted into 50 ureteral units in 42 patients with malignant ureteral obstruction. There were 7 antegrade stents and 43 retrograde stents. There were no major complications. Stent-related symptoms were similar in both kinds of stents. After polymeric stents were replaced with Resonance metallic stents, hydronephrosis subsided or remained stable in 90% (45/50) of the ureteral units. Serum creatinine decreased or remained stable in 90% (38/42) of these patients. The Resonance stent exhibited a mean increase in functional duration of 4 months compared with the polymeric stents (p<0.0001), and 50% (25/50) of the Resonance stents exhibited a significant increase in functional duration (more than 3 months). Pre-operative serum creatinine < 2 was associated with a substantial increase in stent duration.

Conclusions

Resonance stents are effective and safe in relieving malignant ureteral obstructions after polymeric stents failure. Resonance stents can provide a longer functional duration than polymeric stents and should be offered as an option for internal drainage.     

恶性胆道梗阻患者所行经皮穿刺肝内胆管引流术中成功置入金属支架的术前影响因素分析

目的:探讨恶性胆道梗阻患者行PTBD(Percutaneous Transhepatic Biliary Drainage)术中金属支架置入成功率的影响因素。方法:回顾性搜集2010年10月-2017年1月上海市第一人民医院收治的因患有近端恶性胆道梗阻行PTBD术患者的相关临床资料。比较不同原发病因患者支架置入情况。根据患者支架置入是否成功将其分为支架组和非支架组,比较患者的一般临床特征。结果:胰腺癌、胃癌和胆囊癌为本研究中数量上前3位的肿瘤,将以上3组分别按照支架置入数行x~2检验,其中胰腺癌(n=18,支架=6)和胃癌(n=14,支架=11)有统计学意义。将50例患者分为支架组(n=28)和非支架组(n=22),组间比较差异有统计学意义的因素包括:白细胞计数(支架组=6.40±3.40×10~9/L,非支架组=10.74±6.41×10~9/L),中性粒细胞计数(支架组=4.90±3.06×10~9/L,非支架组=8.92±6.25×10~9/L),胆道感染(支架组=9,非支架组=15)。进一步将该50例患者分为6组:胰腺癌-胆道感染组、胃癌-胆道感染组、其他肿瘤-胆道感染组、胰腺癌+胆道感染组、胃癌+胆道感染组、其他肿瘤+胆道感染组。将以上6组分别按照支架置入数行x~2检验,胰腺癌+胆道感染组(n=11,支架=1,P=0.001)有统计学意义。结论:PTBD术对于恶性胆道梗阻是一种有效的姑息治疗手段。胆道感染是PTBD术中支架置入成功的不利因素,胰腺癌合并胆道感染会显著降低PTBD术中支架置入成功率。     

Stent thrombosis in real-world patients: a comparison of drug-eluting with bare metal stents

BackgroundAlthough the introduction of drugeluting stents (DES) has been associated with an impressive reduction in target vessel revascularisation, there has been concern about the safety profile. The aim of this study was to determine the incidence of stent thrombosis in real-world patients and evaluate the contribution of drug-eluting stents. Methods A prospective observational cohort study was conducted at a high-volume centre in Utrecht, the Netherlands. All patients who underwent a percutaneous coronary intervention (PCI) between 1 January and 31 December 2005 were evaluated. The patients were pretreated with aspirin and clopidogrel, which was continued for six months in bare metal stents (BMS) and 12 months in DES. ResultsIn 2005, 1309 patients underwent a percutaneous coronary intervention procedure with stent implantation. After a median follow-up of nine months, 1.8% (n=23) of the patients had suffered from stent thrombosis. Two cases could be attributed to incorrect use of antiplatelet agents. In 8/23 cases, a technical reason was found such as an unrecognised dissection or stent underexpansion. The timing of stent thrombosis was acute in 1/23 patients, subacute in 20/23 patients and late in 2/23 patients. In both cases of late stent thrombosis, a BMS had been used. There were no differences in stent thrombosis rates between DES and BMS (1.4 vs. 1.9%, ns.). This is remarkable since DES were used in more complex and longer lesions. ConclusionThe use of DES in routine daily practice does not appear to be associated with a higher rate of stent thrombosis than BMS. (Neth Heart J 2007;15:382-6).     

Ultrasound diagnosis in endoprosthesis of lower extremity arterial aneurysms with "Hemobahn"- and "Viabahn"-eluted stents

The paper presents the results of color duplex scanning (CDS) in 7 patients treated at the Unit of Vascular Surgery, Clinical Hospital No. 83, from 2002 to 2006, in whom 5 Hemobahn grafting stents and 2 Viabahm ones were implanted into the lower limb arterial aneurysms and the proximal anastomoses of the iliofemoral alloshunts "Gore-tex". A grafting stent was individually selected for each specific case. All the examinees were males. The patients' age was 60 to 70 years. The results of endovascular interventions were assessed, by analyzing color duplex scanning (CDS) of a grafting stent implantation area in early postoperative periods (days 1-3), further by the scheme following 1, 3, 6, and 12 months and then twice a year. Endovascular intervention areas were studied by the standard procedure on Logic-500 and Vivid-700 ultrasound apparatuses (USA) with a 7.5-MHz linear transducer and a 3.5-MHz convection transducer. In the postoperative period, multiprojection scanning was used to detect stent configuration impairments. According to the data of examination using the CDS technique, a surgical success was noted in 100% of cases. In all cases, stage, adequate aneurysmal stenting along with the restoration of the geometry of proximal anastomoses of iliofemoral alloshunts, iliac and superficial femoral arteries with exclusion of aneurysms from blood flow was diagnosed at a hospital stage. Follow-up ultrasonography revealed no changes in the area of endovascular intervention. Thus, as a highly informative, noninvasive technique, CDS can assess the results of implantation of grafting stents into the arteries and shunts of the lower extremities in both early and late postoperative periods.     

PGLA编织支架的制备与初步体内评价

目的:热拉伸会改变纤维的结构和性能,进而影响由纤维编织而成的支架的性能。本文考察了PGLA纤维的拉伸倍数对编织支架在SD大鼠皮下的体内降解行为的影响。方法:制备了基于生物可降解高分子材料聚乙交酯丙交酯(PGLA,GA/LA摩尔比=90/10)的完全生物可降解编织支架,通过测试支架在大鼠体内降解过程中的失重、表面形貌、热性能、径向压缩力等变化情况,考察了纤维的不同的拉伸倍数对支架体内降解过程的影响。结果:用拉伸倍数为5的PGLA纤维编织的支架在植入SD大鼠皮下后降解最慢,重量、吸水率、结晶度、化学成分和径向压缩力的变化最慢,植入体内10天后能够保持完整的支架形态。结论:纤维的拉伸倍数会影响由纤维编织成的支架的热性能和力学性能的变化,本研究结果表明这种新的手工编织的支架具有短暂支撑管腔狭窄的潜在应用,为支架的材料选择和制备方法提供了参考,为在体内起到短暂支撑作用的支架的深入研究提供了实验基础。     

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.     

Leitbakteria of microbial biofilm communities causing occlusion of biliary stents

Biliary stents inserted to relieve obstructive jaundice caused by biliary or pancreatic malignancies inevitably become occluded by microbial growth in the form of diverse microbial community biofilms. The scarce information available on these communities is based on cultivation methods, but such methods usually provide distorted overviews of community composition, so commonalities and differences in biliary stent communities are uncertain. We extracted DNA and RNA from the microbial communities of 11 biliary stents explanted from nine patients in hospitals from two different countries, amplified 16S rRNA and rDNA sequences, analysed the amplicons by the single-strand conformation polymorphism (SSCP) method, and sequenced and deduced phylogenetic assignments of the major amplicons representing the major biofilm community members. We used a Modified Robbins Device (MRD) to study de novo development of a stent biofilm from a patient stent microbial community. Single-strand conformation polymorphism fingerprinting revealed the same six abundant bacterial species, here designated Leitbakteria, namely Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Enterobacter aerogenes, and two unculturable bacteria distantly related to E. coli and Shigella sonnei, in all of the stent biofilm communities. In the experimental biliary stent system, a sequential colonization of the stent surface was observed, with P. aeruginosa being the pioneer colonizer, followed by K. pneumoniae and one of the unculturable Leitbakteria, followed by the remainder of the community. The overview of microbial biofilm communities of biliary stents gained by the use of culture-independent methods revealed new unculturable bacteria as major members of biliary stent biofilms, and the diversity of the abundant members of the stent biofilms is considerably lower than suggested from earlier studies based on cultivation methods, and that communities from different stents from different patients in different countries are remarkably similar and have similar major members, the stent Leitbakteria.     

Degradation Model of Bioabsorbable Cardiovascular Stents

This study established a numerical model to investigate the degradation mechanism and behavior of bioabsorbable cardiovascular stents. In order to generate the constitutive degradation material model, the degradation characteristics were characterized with user-defined field variables. The radial strength bench test and analysis were used to verify the material model. In order to validate the numerical degradation model, in vitro bench test and in vivo implantation studies were conducted under physiological and normal conditions. The results showed that six months of degradation had not influenced the thermodynamic properties and mechanical integrity of the stent while the molecular weight of the stents implanted in the in vivo and in vitro models had decreased to 61.8% and 68.5% respectively after six month''s implantation. It was also found that the degradation rate, critical locations and changes in diameter of the stents in the numerical model were in good consistency in both in vivo and in vitro studies. It implies that the numerical degradation model could provide useful physical insights and prediction of the stent degradation behavior and evaluate, to some extent, the in-vivo performance of the stent. This model could eventually be used for design and optimization of bioabsorbable stent.