scholarly journals A computational framework examining the mechanical behaviour of bare and polymer-covered self-expanding laser-cut stents

2021 ◽  
Author(s):  
Ciara G. McKenna ◽  
Ted J Vaughan
Keyword(s):  
Mechanical Performance ◽  
Bare Metal Stents ◽  
Covered Stent ◽  
Polymer Materials ◽  
Axial Stiffness ◽  
Metal Stents ◽  
Covered Stents ◽  
Computational Framework ◽  
Bending Response

Polymer covered stents have demonstrated promising clinical outcomes with improved patency rates compared to traditional bare-metal stents, however little is known on the mechanical implication of stent covering. In the present work, a combined experimental-computational investigation was carried out to determine the role of a polymeric cover on the biomechanical performance of self-expanding laser-cut stents. Experimental bench top tests were conducted on bare and covered versions of a commercial stent to evaluate the radial, axial and bending response. In parallel, a computational framework with a novel covering strategy was developed that accurately predicts stent mechanical performance, and provides further insight into covered stent mechanics by considering different stent geometries and polymer materials. Results show that stent covering causes increased initial axial stiffness and substantial radial stiffening at small crimp diameters as the cover folds and self-contacts. It was also shown that use of a stiffer polymeric covering material caused significant alterations to the radial and axial response, highlighting the importance of considering the mechanical properties of the combined cover and stent.

Mechanical Evaluation of Polyvinyl Alcohol Cryogels for Covered Stents

2010 ◽  
Vol 4 (3) ◽  
Author(s):  
Jason D. Weaver ◽  
David N. Ku
Keyword(s):  
Polyvinyl Alcohol ◽  
Membrane Damage ◽  
Balloon Catheter ◽  
Bare Metal Stents ◽  
Covered Stent ◽  
Cellular Migration ◽  
Metal Stents ◽  
Membrane Thickness ◽  
Covered Stents ◽  
Increased Risk

Covered stents could reduce restenosis rates by preventing cellular migration with a physical barrier and may have reduced thrombotic complications if an appropriate material is selected. Previous Dacron™ or poly(tetrafluoroethylene) (PTFE) covered stents have had mixed clinical results in part because they are too thick and too thrombogenic at small diameters. Ideally, the covering should be as thin as a stent strut, mechanically able to expand as much as a stent, and durable enough to withstand deployment. As an alternative to PTFE, thin polyvinyl alcohol (PVA) cryogel membranes were tested for their ability to stretch with uniaxial tension tests and for puncture strength with a modified ASTM method. Additionally, PVA cryogel covered stents were made by coating expanded bare metal stents. These covered stents were then hand-crimped onto a balloon catheter and expanded. PVA cryogel membranes were made as thin as 100 μm—thinner than some stent struts—and stretched to approximately 3.0 times their original diameter (similar to a stent during deployment). PVA cryogel membranes resisted puncture well with an average push-through displacement of 4.77 mm—allowing for safe deployment in vessels of up to 9 mm in diameter. Push-through displacement did not depend on membrane thickness in the range tested—a trait that could reduce stent profile without increased risk of puncture. All the PVA cryogel covered stents tolerated the crimping and expansion process well and there was little to no visible membrane damage. In conclusion, based on the results of these mechanical tests, PVA cryogels are mechanically suitable for covered stent membranes. This work represents a first step toward the creation of a new class of covered stent, which could prevent complications from both restenosis and thrombosis.

Covered Stents for Endovascular Treatment of Aortoiliac Occlusive Disease: A Systematic Review and Meta-Analysis

2021 ◽  
pp. 153857442110103
Author(s):  
Austin Mallory ◽  
Stefanos Giannopoulos ◽  
Paul Lee ◽  
Damianos G. Kokkinidis ◽  
Ehrin J. Armstrong
Keyword(s):  
Meta Analysis ◽  
Bare Metal Stents ◽  
Covered Stent ◽  
Primary Patency ◽  
Metal Stents ◽  
Covered Stents ◽  
Stent Group ◽  
Aortoiliac Occlusive Disease ◽  
The Individual

Purpose: The treatment of aortoiliac occlusive disease (AIOD) has largely shifted to endovascular techniques, with primary stenting constituting the preferred treatment approach. The goal of the current study was to summarize available literature and to determine whether covered stents are superior to bare metal stents for the treatment of AIOD, in terms of both periprocedural and long-term outcomes. Methods: A meta-analysis of 47 studies was conducted with the use of random effects modeling. The incidence of adverse events during follow up among the individual included studies was synthesized. Results: Most of the lesions were located at the common iliac arteries and were chronic total occlusions. The procedure was technically successful in almost all cases in both groups, with a low rate of periprocedural complications observed in both groups. The reported primary patency rates for the non-covered and covered stent group during an average follow up of 24.3 months among the individual studies, were 84% and 92% respectively, while surgical or endovascular re-intervention was required in 10% of non-covered stent cases and in 6% of covered stent cases. Eight studies comparing covered vs non-covered stents in terms of patency demonstrated superiority of covered stents (OR: 2.47; 95% CI: 1.01-6.01; p = 0.047 Combining TASC C/D lesions together 12 studies reported 92% (95%CI:89%-95%) primary patency in the covered stent group, while 7 studies reported 75% (95%CI: 60%-88%) primary patency for cases treated with non-covered stents. Conclusion: This study demonstrated that covered stents are safe and effective when utilized for the treatment of AIOD. Covered stents were associated with a statistically significant higher odds of primary patency in both the overall cohort and in more complex TASC C/D lesions. However, additional high-quality comparative analyses between covered vs bare metal stents and between several types of covered stents are needed to determine the most optimal treatment modality for AIOD.

Transbrachial and transfemoral approaches combined with visceral protection for the treatment of juxtarenal aortoiliac occlusive disease: Technical issues and clinical outcomes

Vascular ◽  
2021 ◽  
pp. 170853812110232
Author(s):  
Peixian Gao ◽  
Changliang Li ◽  
Xuejun Wu ◽  
Gang Li ◽  
Dianning Dong ◽  
...  
Keyword(s):  
Endovascular Treatment ◽  
Bare Metal Stents ◽  
Covered Stent ◽  
Occlusive Disease ◽  
Metal Stents ◽  
Infrarenal Aorta ◽  
Bare Metal ◽  
Stent Grafts ◽  
Aortoiliac Occlusive Disease

Purpose To evaluate the safety and efficacy of transbrachial and transfemoral approaches combined with visceral protection for the endovascular treatment of juxtarenal aortoiliac occlusive disease (AIOD) over an average 19-month follow-up period. Methods In this retrospective analysis, all patients with juxtarenal AIOD at a single institution were reviewed from June 2015 to January 2020. Patient characteristics, angiographic results, and follow-up outcomes were retrospectively recorded. The indications for treatment were critical limb threatening ischemia in 12 patients and bilateral claudication in five patients. Percutaneous access via the left brachial artery was first obtained to recanalize the infrarenal occluded lesions. After that, femoral accesses were achieved. A 4-Fr catheter, a 4 mm balloon, or a 6-Fr 90-cm-long sheath was used to complete visceral artery protection. Results A total of 17 juxtarenal AIOD patients (14 males; mean age, 63.4 ± 8.1 years) underwent endovascular treatment. The technical success rate was 100%. Complete reconstruction was achieved in 15 (88.2%) patients. The infrarenal aorta was reconstructed with kissing covered stent grafts ( n = 7), kissing bare-metal stents ( n = 2), covered stent grafts ( n = 2), bare-metal stents ( n = 1), or the off-label use of iliac limb stent grafts ( n = 5). Renal embolization was found in 3 (17.6%) patients during intraoperative angiography. There was 1 (5.9%) case of distal runoff embolization after CDT and 1 (5.9%) case of left iliac artery rupture. One (5.9%) death occurred due to acute myocardial infarction 20 days after the operation. The average follow-up period was 19.3 ± 16.7 months (range, 1–54 months) in the remaining 16 cases. The renal artery patency rate was 100%. The estimated cumulative primary patency rates were 92.3% at 12 months and 59.3% at 36 months according to the Kaplan–Meier method. Conclusions Transbrachial and transfemoral approaches combined with visceral protection offer a safe and effective alternative to open revascularization for the endovascular treatment of juxtarenal AIOD.

scholarly journals Stricture recanalisation of the distal urether with various endoprothesis

2010 ◽  
Vol 57 (2) ◽  
pp. 61-64 ◽  
Author(s):  
A. Mladenovic ◽  
K. Davidovic ◽  
B. Markovic ◽  
P. Anojcic ◽  
M. Stojadinovic ◽  
...  
Keyword(s):  
Percutaneous Nephrostomy ◽  
Covered Stent ◽  
Metallic Stents ◽  
Metal Stents ◽  
Covered Stents ◽  
Important Place ◽  
Distal Ureter ◽  
Number Of Patients ◽  
Study Results ◽  
New Generation

Introduction: Application of the metallic stents in the interventional uroradioligy is the result of continuous development of the new generation methods percutaneous nephrostomy (PCN), ballon catheter dilatation (BCD), methal and covered stent application. Application of metal stents in the renal canal system was attempted in order to eliminate BCD and PCN - related limitations as well as poor therapeutic results of these methods in a number of etiopathogenic groups of urinary stasis. Years - long application of interventional uroradiology methods, until the development of metallic stengts had shown the following therapeutics facts: PCN is incapable to resolve the cause of urinary obstruction. Permanent good therapeutic BCD results mostly depend on pathohistological aspect of the stricture, metallic stents are most frequently the last choice in therapeutics approch to urinary tract obstructions and their application is directly dependent on previous therapeutics results accomplished by PCN and BCD. In therapeutical sequences new generation of covered stents have important place as method of selection in patients of irreversible uroopstruction of distal ureter. Objective: The main goal of this study was to analyze therapeutics results, advanteges and shortages of insercion plastics and opened metallic endoprothesis, and to analyze results of covered methal applications on the contrary of using older interventional uroradiology methods. Method: Sixthytwo patients with distal urether strictures threated in the Deparment of interventional uroradiology Institute of Radiology Clinical centre of Serbia in Belgrade, participated in the study. Results were analyzed with Person's 2- test, Fisher test and Student T-test. Results: In our study we had highly significant differences in comparison with number of patients and type of stents during the time after recanalization was reached. Also it was highly significant differences according the type of used interventional uroradiology method that treated proliferation and the success of recanalization. Conclusion: Application of covered temporary uretheral stents have number advantages against using generation older permanent methal endoprothesis.

scholarly journals SS14. Comparison of Covered Stents versus Bare Metal Stents for Treatment of Chronic Atherosclerotic Mesenteric Arterial Disease

2012 ◽  
Vol 55 (6) ◽  
pp. 23S ◽  
Author(s):  
Gustavo S. Oderich ◽  
Luke Erdoes ◽  
Christopher LeSar ◽  
Peter Gloviczki ◽  
Audra A. Duncan ◽  
...  
Keyword(s):  
Bare Metal Stents ◽  
Arterial Disease ◽  
Metal Stents ◽  
Covered Stents ◽  
Bare Metal

Stenting across head and neck vessels using covered stents for persisting aortic arch obstruction

2012 ◽  
Vol 22 (5) ◽  
pp. 610-614 ◽  
Author(s):  
James R. Bentham ◽  
Nilesh Oswal ◽  
Robert Yates
Keyword(s):  
Head And Neck ◽  
Aortic Arch ◽  
Stent Placement ◽  
Bare Metal Stents ◽  
Coarctation Of The Aorta ◽  
Metal Stents ◽  
Covered Stents ◽  
Bare Metal ◽  
Endovascular Stent ◽  
Endovascular Stent Placement

AbstractObjectiveTo describe endovascular stent placement using partially covered stents to preserve flow in head and neck vessels.BackgroundEndovascular stent placement has become established as a first-line therapy for native coarctation of the aorta or re-coarctation in older children and adults. Increasingly covered stents are becoming the preferred option over bare-metal stents because of the perceived lower risk of aneurysm formation. Open-cell bare-metal stents are chosen when there is a high likelihood of jailing a head and neck vessel. Here we describe partial uncovering of a covered stent before implantation to allow flow through the uncovered portion of the stent to the branch vessel but preserve the covering over the majority of the remaining stent.MethodsWe describe two cases with aortic arch hypoplasia and re-coarctation, both of which required two partially uncovered stents for a satisfactory result.ConclusionsEndovascular stent placement is becoming the preferred option in the management of coarctation of the aorta in older children and adults. Strategies to deal with transverse arch hypoplasia and multiple levels of aortic arch obstruction frequently involving branch vessels or aneurysms need to be considered before these procedures are embarked upon. Partially uncovering stents may afford more protection than using bare-metal stents in the transverse and distal arch while preserving flow in head and neck branches, and is a technically straightforward procedure.

Sign in / Sign up

Export Citation Format

Share Document