Design and Finite Element Analysis of a Novel Retrievable Vascular Stent / 医用生物力学

Objective In order to avoid early restenosis after drug-eluting stent (DES) implantation, the retrievable structure of the NiTi alloy stent and its biomechanical analysis were studied. Methods The geometric models of the retrievable vascular stent and the retrieval system were established. The retrieval part of the stent consisted of four symmetrically distributed tendons, which were designed as circular meshes. The distribution of the maximum strain during stent compression and its uniformity during compression and self-expansion were analyzed, and the simulation experiments of the retrieval process were also performed. Results The maximum strain of the stent was 3.7% and the index of non-uniformity (INU) was 0.62% when the stent was compressed to the minimum size. While the IBU was 1.31% after the self-expansion process completed. The maximum strain was 1.2% when half of the stent was retrieved into the outer sheath. Conclusions The stent could be safely and successfully retrieved into the outer sheath as the strain was within the bearable range of the material and the compression and self-expansion process was relatively uniform. The research findings provide important references for structural design, biomechanical analysis and potential clinical applications of the novel retrievable vascular stent.

Surgical Removal of the Inferior Vena Cava Filter Using Minimal Cavotomy: A Case Report

The use of retrievable inferior vena cava (IVC) filters has markedly increased in the recent years. However, the failure rate for the retrieval of the IVC filters using the endovascular method is reported to be up to 19%. Open surgical removal of the IVC filters is technically challenging and may require longitudinal cavotomy, clamping, and repair of the IVC. Here, we present a case of successful open surgical removal of the IVC filter using minimal cavotomy. This technique is an effective method after a failed endovascular removal attempt.

First-in-man implantation of the retrievable and repositionable VenusA-Plus valve / 世界急诊医学杂志（英文）

BACKGROUND:No retrievable and repositionable second generation transcatheter aortic valve is available in China. Here, we report the first-in-man implantation of the retrievable and repositionable VenusA-Plus valve. METHODS:A 76-year-old patient with symptomatic severe aortic stenosis and high surgical risk (STS 13.8％) was recommended for transcatheter aortic valve replacement (TAVR) by heart valve team. Type 0 bicuspid aortic valve with asymmetric calcification was identified by dual source computed tomography, and the unfavorable anatomies increased the possibility of malposition and paravalvular leakage during TAVR. Therefore, we used the retrievable and repositionable VenusA-Plus valve for the patient. RESULTS:Transfemoral TAVR was performed under local anesthesia with sedation, and a 26-mm VenusA-Plus valve was successful y implanted. No transvalvular pressure gradient and trace paravalvular leakage were found. CONCLUSION:The successful first-in-man implantation indicates the retrievable and repositionable VenusA-Plus valve is feasible in complicated TAVR cases such as bicuspid aortic valve.

Diversity of retrievable heterotrophic bacteria in Kongsfjorden, an Arctic fjord

Abstract The diversity and abundance of retrievable pelagic heterotrophic bacteria in Kongsfjorden, an Arctic fjord, was studied during the summer of 2011 (June, August, and September). Retrievable bacterial load ranged from 103 to 107 CFU L−1 in June, while it was 104-106 CFU L−1 in August and September. Based on 16S rRNA gene sequence similarities, a higher number of phylotypes was observed during August (22 phylotypes) compared to that during June (6 phylotypes) and September (12 phylotypes). The groups were classified into four phyla: Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes. Bacteroidetes was represented only by a single member Leewenhoekiella aequorea during the three months and was dominant (40%) in June. However, this dominance changed in August to a well-known phytopathogenic species Rhodococcus fascians (32%), which could be a result of decrease in the phytoplankton biomass following the secondary bloom. It is the first report of Halomonas titanicae isolation from the Arctic waters. It showed an increase in its abundance with the intrusion of Atlantic water into Kongsfjorden. Increased abundance of Psychrobacter species in the late summer months coincided with the presence of cooler waters. Thus, the composition and function of heterotrophic bacterial community was fundamentally different in different months. This could be linked to the changes in the water masses and/or phytoplankton bloom dynamics occurring in Arctic summer.

Rescue stent implantation for the treatment of acute ischemic stroke: initial experience in 13 patients / 介入放射学杂志

Objective To evaluate the safety and efficacy of stent implantation used as a rescue measure for acute ischemic stroke.Methods The clinical data of 13 patients with acute ischemic stroke caused by large artery occlusion of anterior c erebral circulation that occurred within 8 hours before clinical visit,who had received rescue stent implantation at authors' hospital,were retrospectively analyzed.Before stent implantation,all patients failed to respond to other recanalization treatments,including intravenous thrombolysis,intra-arterial thrombolysis,mechanical thrombec tomy with Penumbra device,and Solitaire stent thrombectomy.Angiography was performed immediately after stent implantation.Vascular recanalization condition was evaluated with blood flow grading that was based on thrombolysis in cerebral infarction (TICI) criterion.Perioperative bleeding and complications were recorded.National Institutes of Health Stroke Scale (NIHSS) score was used to assess the improvement of neurological function at one week after operation.Modified Rankin scale (mRS) score was used to evaluate the prognosis at 3 months after operation.Results A total of 16 stents were implanted in 13 patients.Before stent implantation,thrombectomy by using Solitaire retrievable stent was employed in 10 patients,mechanical thrombectomy with Penumbra device was adopted in 3 patients,intravenous thrombolysis with urokinase was used in one patient,and intra-arterial thrombolysis with urokinase was conducted in one patient.After stent implantation,partial or complete recanalization was achieved in 12 patients (TICI≥2b/3).NIHSS score was improved from preoperative (16.15±5.81) points to postoperative (8.08±5.61) points,the difference was statistically significant (P＜0.05).Three months after stenting treatment,good prognosis (mRS ≤2) was obtained in 7 patients (53.8％) and 2 patients died.Intracranial hemorrhage occurred in 2 patients and procedure-related embolism was observed in 3 patients.Conclusion For the treatment of acute ischemic stroke,intracranial stenting angioplasty,used as a rescue measure for thrombolytic therapy with different combinations of drugs,is safe and effective.

Technique for retrieval of celect filters in difficult cases / 中国介入影像与治疗学

Objective To explore the techniques and strategies for the retrieval of the retractable inferior vena cava filter (IVCF).Methods Celect IVCF retrieval was not removed successfully with Gtünther Celect recovery device in 9 cases and exchange-wire-loop removal of inferior vena cava filter method were applicated.Results The longest implanted time of 9 patients was 142 days,the shortest implanted time was 37 days,and the average time was (88.67±33.85)days.Eight fil ters were successfully removed and one failed due to severe bending of inferior vena cava.Filter retrieval rate was 88.89％ (8/9).The average retrieval time was (69.89± 12.12)min (57-162 min).No perforation of the wall and contrast agent were found in all patients after the inferior vena cava angiography.Conclusion For the retrieval of the hook heavily atta ched to the IVCF,the retrieval technique of using the exchange wire into the loop method can effectively improve the retrieval rate and has a certain clinical value.

Recanalization of Acute Intracranial Artery Occlusion Using Temporary Endovascular Bypass Technique / 신경중재치료의학

PURPOSE: The purpose of this study is to present our preliminary experience of the temporary endovascular bypass (TEB) technique using an Enterprise stent for recanalization of acute intracranial artery (IA) occlusion. MATERIALS AND METHODS: Patients treated by TEB were enrolled in this retrospective study from January 2009 to May 2010. All the procedures consist of temporary partial deployment and subsequent retrieval of Enterprise stent, supplemented by intra-arterial infusion of urokinase (UK) and/or tirofiban. According to the thrombolysis in cerebral infarction (TICI) classification, recanalization was evaluated with initial and postprocedural angiography. Safety was evaluated related to the procedure and clinical outcomes were assessed by National Institute of Health Stroke Scale (NIHSS) score at discharge and modified Rankin scale (mRS) score at 3 months. RESULTS: Eleven patients (median NIHSS 12.8, mean age 61.6 years, male: female = 8:3) with acute IA occlusion were treated with TEB. All the patients presented with TICI 0, and the occluded vessel was the middle cerebral artery (n=7), the basilar artery (n=1), and the distal ICA occlusion (n = 3). IV infusion of tissue plasminogen activator (tPA) was done in 4 patients and mechanical thrombolysis with intra-arterial UK was performed in 9. Recanalization was achieved in 73% (8 patients; TICI > or = 2). There were no procedure-related complications except for two asymptomatic intracranial hemorrhages. Improvement (> or = 4 points on the NIHSS) and good outcome (mRS < or =2) after 90 days was shown in six patients (55%). One patient died 6 days after procedure. CONCLUSION: TEB may be a valuable treatment option in acute thromboembolic IA occlusion without stent implantation.

Critical Use of Balloon Angioplasty after Recanalization Failure with Retrievable Stent in Acute Cerebral Artery Occlusion

OBJECTIVE: Sudden major cerebral artery occlusion often resists recanalization with currently available techniques or can results in massive symptomatic intracranial hemorrhage (sICH) after thrombolytic therapy. The purpose of this study was to examine mechanical recanalization with a retrievable self-expanding stent and balloon in acute intracranial artery occlusions. METHODS: Twenty-eight consecutive patients with acute intracranial artery occlusions were treated with a Solitaire retrievable stent. Balloon angioplasty was added if successful recanalization was not achieved after stent retrieval. The angiographic outcome was assessed by Thrombolysis in Cerebral Infarction (TICI) and the clinical outcomes were assessed by the National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Scale (mRS). RESULTS: At baseline, mean age was 69.4 years and mean initial NIHSS score was 12.5. A recanalization to TICI 2 or 3 was achieved in 24 patients (85%) after stent retrieval. Successful recanalization was achieved after additional balloon angioplasty in 4 patients. At 90-day follow-up, 24 patients (85%) had a NIHSS improvement of > or =4 and 17 patients (60%) had a good outcome (mRS < or =2). Although there was sICH, there was one death associated with the procedure. CONCLUSION: Mechanical thromboembolectomy with a retrievable stent followed by additional balloon angioplasty is a safe and effective first-line therapy for acute intracranial artery occlusions especially in case of unsuccessful recanalization after stent thrombectomy.

Intraoral framework pick-up technique to improve fit of a metal-resin implant prosthesis.

The achievement of passive fit is an important prerequisite for the prevention of complications in full-arch screw-retained implant prosthesis. With cemented prosthesis, the cementation compensates for the discrepancies in the cast framework, but the lack of retrievability seems undesirable. The aim of this paper is to propose a modified screw-retained prosthesis design for complete arch implant fixed rehabilitation. A technique for the fabrication of a full-arch metal-resin implant-supported screw-retained prosthesis is described. Cementation of the framework to the abutments intraorally improves the passivity of fit of the prosthesis on the implants. Maintenance of screw-access channels in the final prosthesis ensures retrievability. The metal-resin design allows for easy repair and maintenance. The prosthesis is cost-effective compared to conventional options and can be employed as a viable treatment alternative when considering metal-acrylic resin complete arch fixed prosthesis.

Immediate placement and loading of implants in anterior maxilla using an altered screw-retained implant fixed prosthesis.

This article describes the immediate placement and loading of implants in the aesthetic zone using an implant-retained, fixed prosthesis with a modified design. One section of the implant prosthesis has cemented crowns and the other section is the conventional screw-retained. This combined approach significantly offsets the unsuitable implant position, alignment or angulation, while ensuring the easy retrievability, repair and maintenance of the prosthesis at the same time.

Clinical application of retrievable vena cava filters / 国际外科学杂志

Retrievable vena cava filters can be used to prevent pulmonary embolism. The advantage of the retrievable vena cava filters is that they can either be removed or be remained in the vena cava permanently if needed. This article describes the current status of retrievable vena cava filters including indications, outcomes, patient management, time of filter removal, and the management of thrombus in the filter.

Indicaciones actuales del implante de filtros recuperables en la vena cava inferior

El tromboembolismo venoso es una patología que ocurre aproximadamente en 1 de cada 1 000 personas en el mundo, de las cuales más de la mitad corresponde a casos de trombosis venosa profunda. La principal complicación aguda de la trombosis venosa profunda es el embolismo pulmonar, que resulta fatal en 20%-30% de los casos. La anticoagulación es la estrategia más eficaz para la prevención de esta complicación, sin embargo, está contraindicada en situaciones frecuentes. Los filtros de vena cava inferior constituyen una alternativa no farmacológica para la prevención del embolismo pulmonar en aquellos pacientes que presentan trombosis venosa profunda. Este artículo hace revisión de los aspectos históricos de estos dispositivos, con especial interés en los denominados filtros recuperables, en cuanto a sus indicaciones, técnica de colocación-retiro, eficacia y seguridad

Venous thromboembolism is a disease which occurs in 1 out of 1000 people around the world, accounting for about a half of cases of deep venous thrombosis. Deep venous thrombosis major complication is pulmonary embolism, fatal in 20%-30% of cases. Anticoagulation is the most effective strategy to prevent pulmonary embolism, however, this is contraindicated in frequent clinical situations. Inferior vena cava filters are a non-pharmacological alternative in these cases. This article reviews historical aspects of these devices, with particular interest in those denominated retrievable filters, describing indications, implantation-retrieval technique, efficacy and safety

Retrievable stent filter placement for the treatment of Budd-Chiari syndrome complicated with inferior vena cava thrombosis: its mid-term results / 介入放射学杂志

Objective To investigate the mid-term efficacy of retrievable stent filter placement for the treatment of Budd-Chiari syndrome (BCS) complicated with inferior vena cava (IVC) thrombosis. Methods Eight patients of BCS complicated with IVC thrombosis were enrolled in this study. IVC thrombosis included segmental occlusion (n = 2) and membranous occlusion (n = 6). In all patients, the IVC was re-canalized by using blunt wire after anticoagulation and thrombolytic therapy, then, the re-canalized site was expanded with small balloon, which was followed by the placement of retrievable stent filter, and, finally, IVC size was dilated with larger balloon. Anticoagulation and thrombolytic therapy was given after the procedure. And all the retrievable stent filters were withdrawn from the IVC through internal jugular vein when the thrombus in IVC was dissolved. In patients with segmental occlusion of IVC, in addition to the placement of retrievable stent filter a "Z" type vessel stent was also placed during the same interventional session. Follow-up examination with color Doppler sonography was conducted in all patients. Results Technical success was achieved in all 8 patients without pulmonary infarction or other complications both during and after the operation. Immediately after the thrombus completely disappeared, the retrievable stent filter was successfully taken out in all patients. During a following-up period of 3-12 months, color Doppler sonographs showed that the IVC remained patent in 6 patients and had a recurrence of stenosis in 2 patients. Conclusion Placement of retrievable stent filter is a safe and effective treatment for BCS complicated with IVC thrombosis.