Effects of Plaque Eccentricity on Biodegradable Polylactic Acid Stent Implantantion in Stenotic Vessels / 医用生物力学

Objective To study the effect of plaque eccentricity on stent performance and stress distributions of artery and plaque during stent implantation in stenotic vessels. Methods The stent and idealized stenotic vessels were constructed, and 4 different eccentricities (0%, 20%, 40%, 60%) were attributed to the plaque. Then the stent recoil, stent foreshortening, and stress distributions of artery and plaque when the stent was expanded to the target displacement were analyzed by the finite element method. Results Along with the increase of plaque eccentricity, both stent recoil and stent foreshortening gradually grew. At the same time, the stress of artery and plaque also showed an increasing tread, and high-stress areas gradually approached the narrow side. The maximum von Mises stress of the plaque was much greater than that of the artery. Conclusions Plaque eccentricity had a certain effect on performance of the stent and stress distributions of stenotic vessels. In stent design, the geometry of the plaque should be considered to improve clinical effect of the stent in interventional treatment.

Structure Design and Mechanical Analysis of a Novel Biodegradable Zinc Alloy Stent / 医用生物力学

Objective To compare and analyze the mechanical performance of a new biodegradable stent and a common stent and their effects on treating the stenotic vessels. Methods Using finite numerical simulation, the new stent and the common stent were implanted into vessels with a diameter stenosis of 30%, and their support performance and influences on reshaping the stenotic vessels were investigated. Results The radial recoiling ratio and dog-boning ratio of the new stent were decreased by 26.6% and 34.7%, respectively, compared with the common stent. Besides, the stenotic vessel deployed with the new stent recoiled less and had a flatter and larger lumen. Conclusions Compared with the common stent, the new stent has stronger scaffold performance and a better therapeutic effect on stenotic vessels. The new stent with stronger scaffold performance is highly expected to be an alternative choice in interventional surgeries.

Insertion of biodegradable silicon-covered magnesium alloy stent in esophagus, a preliminary in vitro and in vivo study of feasibility and tissue reaction in experimental rabbits / 介入放射学杂志

Objective To study the mechanical properties and degradation behavior of biodegradable silicon-covered magnesium alloy stent in vitro,to investigate the technical feasibility of its implantation into rabbit esophagus and to observe the tissue reaction in vivo.Methods The mechanical compression recovery properties and the degradation behavior of biodegradable silicon-covered magnesium alloy stent were tested in vitro.A total of 30 healthy Holland rabbits were randomly divided into silicon-covered magnesium alloy stent group (n=15) and control group (n=15).For rabbits in the silicon-covered magnesium alloy stent group fluoroscopy-guided insertion of the stent into the lower third segment of esophagus was conducted,while for rabbits in the control group no intervention was adopted.One,2 and 4 weeks after the implantation of the stent,esophagography was performed for all rabbits of both groups,and each time every 5 rabbits from both groups were sacrificed,the specimens were collected and sent for histological examinations.Results In vitro test indicated that biodegradable silicon-covered magnesium alloy stent had good flexibility and elasticity,and in phosphate-buffered saline with pH 4.0 or pH 7.4 it degraded more slowly than bare magnesium alloy stent.In vivo test showed that the stent implantation could be well tolerated by all experimental rabbits.Before stent insertion the esophageal diameter was(9.2±0.8) mm,and at one,2 and 4 weeks after stent insertion the esophageal diameters were (9.7±0.7) mm,(9.6±0.8) mm and (9.6±0.5) mm respectively (P＞0.05).In the silicon-covered magnesium alloy stent group,stent displacement occurred in 6 rabbits in one week (n=l),2weeks (n=1) and 4 weeks (n=4).After stent implantation,the tissue reactions such as esophageal wall injury,collagen deposition,etc.were not obviously different from those in the control group (P＞0.05).Conclusion It is technically feasible to insert silicon-covered magnesium alloy stent into the rabbit's esophagus,the stent can provide sufficient support for at least 2 weeks,the stent displacement rate is low and acceptable,and no severe esophageal wall injury and collagen deposition are observed.

Biodegradable biliary stents: a new approach for the management of hepaticojejunostomy strictures following bile duct injury. prospective study / Stent biliar biodegradável: uma nova abordagem para as estenoses hepaticojejunais após lesão do ducto biliar. estudo prospectivo

ABSTRACT Background: Once a biliary injury has occurred, repair is done by a hepaticojejunostomy. The most common procedure is to perform a dilatation with balloon with a success of 70 %. Success rates range using biodegradable stents is from 85% to 95%. Biodegradable biliary stents should change the treatment of this complication. Aim: To investigate the use of biodegradable stents in a group of patients with hepaticojejunonostomy strictures. Methods: In a prospective study 16 biodegradable stents were placed in 13 patients with hepaticojejunostomy strictures secondary to bile duct repair of a biliary surgical injury. Average age was 38.7 years (23-67), nine were female and four male. All cases had a percutaneous drainage before at the time of biodegradable stent placement. Results: In one case, temporary haemobilia was present requiring blood transfusion. In another, pain after stent placement required intravenous medication. In the other 11 patients, hospital discharge was the next morning following stent placement. During the patient´s follow-up, none presented symptoms during the first nine months. One patient presented significant alkaline phosphatase elevation and stricture recurrence was confirmed. One case had recurrence of cholangitis 11 months after the stent placement. 84.6% continued asymptomatic with a mean follow-up of 20 months. Conclusion: The placement of biodegradable stents is a safe and feasible technique. Was not observed strictures caused by the stent or its degradation. It could substitute balloon dilation in strictures of hepaticojejunostomy.

RESUMO Racional: Uma vez que lesão biliar ocorreu, o reparo é feito por hepaticojejunostomia. O procedimento mais comum é efetuar dilatação com balão com sucesso de 70%. As taxas de sucesso utilizando stents biodegradáveis ​​é de 85% a 95%. Stents biliares biodegradáveis ​​devem mudar o tratamento desta complicação. Objetivo: Investigar o uso de stents biodegradáveis em um grupo de pacientes com estenose hepaticojejunal Métodos: Em estudo prospectivo 16 stents biodegradáveis ​​foram colocados em 13 pacientes com estenose de hepaticojejunostomia secundárias usados para reparação do ductos biliares de lesão cirúrgica. A média de idade foi de 38,7 anos (23-67), nove pacientes eram homens e quatro mulheres. Todos os casos tiveram drenagem percutânea antes do momento da colocação de stent biodegradável. Resultados: Em um caso, haemobilia temporária estava presente com necessidade de transfusão de sangue. Em outro, dor após a colocação do stent necessitou de medicação intravenosa. Nos outros 11 pacientes, alta hospitalar foi na manhã seguinte após o procedimento. Durante o seguimento, nenhum apresentou sintomas durante os primeiros nove meses. Um paciente apresentou significativa elevação da fosfatase alcalina por recidiva da estenose. Um caso teve recorrência de colangite 11 meses após a colocação do stent. Continuaram assintomáticos 84,6% com média de acompanhamento de 20 meses. Conclusão: A colocação de stents biodegradáveis ​​é técnica segura e viável. Não foram observadas restrições causadas pelo stent ou pela sua degradação. Stent pode substituir dilatação com balão na estenose de hepaticojejunostomia.

The safety and therapeutic efficacy for application of biodegradable stent excel with biodegradble polymer combined with firofiban in patients with acute coronary syndrom / 中华急诊医学杂志

ObjectiveTo evaluate the safety, and the brief-and prolongedterm therapeutic efficacy for im- plantation of biodegradable stent Excel combined with Tirofiban made in China into patients with acute coronary syndrome(ACS). MethodA total of 301 patients were divided into Excel group (n = 100), Cypher group (n =102) and bare metal stem(BMS) (n = 99). The Tirofiban used in three groups was administered intravenously during and after operation.The loading dose of Tirofiban was 10 μg/kg given within 3 min followed by a Tirofiban intravenous maintenance infusion in 0.15 μg/(kg·min) with micro pump for 48 hours. Safety and efficacy were compared among three groups after stents implantation by the observation of TIMI flow, complication of bleeding, changes of platelet count, haematoglobin and hematocrit, incidence of angina, acute and subacute thrombosis inner stent and major adverse cardiac events (MACE) (cardiac death, nonfatal myocardial infarction and target ves-sel revascularization). Follow-up information got from out-patient clinic and telephone call including incidence of angina, MACE and rehospitalization were comapared sucessively 1 month, 6 monthes and 12 monthes after dis- charge. ResultsAmong there groups,there were no significant differences in demographics,and physical and lab-oratory findings before treatment. Successful rate of implantation was 100 percent and the TIMI flow of class Ⅲ was found in all patients. There was no complication of stroke and massive hemorrhage of gastrointestinal tract, and no significant differences in complication of bleeding, platelet count, hemoglobin and hematocrit after implantation. Incidence rates of acute thrombosis were 0, 0.98 and 1.01 percent in three groups, and there was no significant difference in acute thrombosis inner stent among three groups (P >0.05). The rates of angina, sub.acute stent thrombosis, MACE and rehospitalization among three groups had no differences at 1 month and 6 monthes follow-up (P > 0.05), but significant differences were not found until 12 monthes follow-up (P < 0.05). Conclusions Drug-eluting stent Excel with biodegradable polymer combined with Tirofiban made in China implanted in patients with ACS were capable of preventing acute and later thrombosis inner stent. This procedure had favourable safety, and brief-term and proionge-term therapeutic efficacy.

Research progress of biodegradable stent in the application for benign luminal stenosis / 介入放射学杂志

Stent implantation plays an significant role in the interventional therapy, mainly with permanent stent, possessing many disadvantages such as restenosis and inflammatory hyperplasia and can thus hardly be used in children and nonmalignant stenosis. Biodegradable stent has theoretical capability to solve these problems and acquires a bright future. Nowadays, with the development of material industry and manufacture craft, biodegradable stent technique has turned up to be mature in last decades. Through the strict animal experiments and prophase of clinic application, satisfactory result has been acquired. We believe that bioabsorbable stent will be widely used in many benign diseases which would be a good supplement for permanent stent in the near future.