Stents - Science topic

Suppose austenite finish temperature of Niti alloy wire A is 25 deg Celsius and Niti wire B is 35 deg Celsius. Which one is best recommended for Biliary stent application and why?

I am working on the measurement of radial forces exerted by self-expandable cardiovascular stents. I need to know how much force can damage the intima of arterial walls? Please refer me to a research or article with the values.

I am trying to model a parallel plate compression test for a bioresorbable stent, by using just 1/2 model. With one design everything went perfect, when I uploaded the other one (same BCs, same properties...) it doesn't work. Abaqus says that the strain is too high. I tried to distance the shell plate to 1 mm (as you can see here https://www.transfernow.net/dl/20240519I0ZLE9Ss) to see if there was any change, but nothing. Do you know how can I resolve this?

To be complete, I put as BCs: symmetry on the faces cut in half (loading step) and fixed just one node of the stent along the axial direction (in INITIAL step, not loading). Thanks in advance.

I have done a stress-strain test and it looks like the picture attached. However, in here, I only have upper and lower plateau stresses.

In Auricchio's model for the superelastic behavior of nitinol material, four parameters and constant are required to model the behavior. How can I extract these parameters from my test?

What I have from my test: upper plateau stress, lower plateau stress, elongation, residual elongation

What I need for the modeling: Sigma_s and Sigma_f for both forward and reverse phase transformations (four constants as shown in the attached picture), residual strain.

The problem I am trying to solve is to study how erosion happens and what occurs to the device , for instance a stent , physically , that is obtain the eroded new geometry that can then be analyzed in Ansys Mechanical to learn about it's structural integrity, stability ,etc. Can this workflow be achieved using the GUI of the Ansys Fluent and Ansys Mechanical. For example using chemical analysis part in Ansys Fluent maybe?

Note: DPM is not relevant here as there the eroding particles are extra solids that hit and scrap away the solid object (pipe and such).

Choanal atresia is a congenital blockage of the posterior end of the nasal cavity.

I am simulating the crimping of a stent in ABAQUS/Standard using a 3D deformable cylinder on which I impose a displacement in order to crimp the stent from an initial diameter of 2.5 mm to a final 1 mm.

After doing the simulation I'm interested in obtaining the radial strength. According to FDA, the radial strength is the pressure at which a stent experiences irrecoverable deformation. So the idea is to plot this pressure (y-axis) with respect to the strain or radial displacement(x-axis).

Do you have any suggestion?

Greetings, I am David junior doctor from Georgia.

I will be concise

Patient came to us with Chiari's Triad, an aortic-esophageal fistula was diagnosed. In esophagus and aorta stent grafts were inserted, after this procedure extravasation of contrast can not be seen in the aneurysm sac. However, the patient has episodes of severe pain and after vomiting the blood mass symptoms decrease in severity. After ct scan with contrast The aneurysm sac has no active blood supply source. In the attached file you can see the laminar flow in the exact location of aorta where the fistula was before inserting the stent. After conference, held in our hospital, it is assumed that we are dealing with some venous involvement, which causes a sluggish increase in pain. The patient is still held in ICU and waiting for our next decision. If you had a similar case, what was the next tactic? I would love to hear your advice from your experience to help the patient

I have a disruptive question to ask those researching and practicing lower extremity biomechanics that reinforces the fact that hyperpronation is a biomechanical red herring:

If Subtalar Joint Stenting (SJS) is indicated to correct a "hyperpronated" subtalar joint, why is it that as talar declination does improve when stenting or dispensing a custom foot orthotic does the calcaneal inclination angle remain relatively or completely unchanged?

Perhaps the biomechanical correction of a STJ stent or custom foot orthotic actually is working to reverse biomechanical pathology in the ankle joint instead?

If so, what is the stent or orthotic correcting so effectively against gravity and grf?

As per title, I'm interested in knowing whether any commercially available (not research based), medical devices are manufactured (even if partly) through the polymerisation of monomers using photoinitiators such as Irgacure, Eosin-Y, riboflavin etc. Specifically, polymerisation of the material outside of the body. Equivalent to the polymerisation of a polymeric coating on a stent within a manufacturing facility.

Blockage of arteries is a common problem during theses days, which may lead to myocardial infraction or heart attack. Once the plaque is formed, it cant be removed. The problem can be overcome either through bye-pass surgery of heart or by putting a stent at blocked portion of the arteries. So my request is to know that is there any chemical individually or in combination in Allopathy / Ayurveda that can reverse the plaque formation.

The widespread use of ureteral double J stents preventing renal damage do not take in sight the ureteral damage or the time resolving the obstrucción.

I am doing an analysis on the stent structure where

In Step 1: I am expanding the stent from its crimped state to expanded state using radial boundary Condition.

In step 2: I want to remove the stress generated during the previous step on the stent structure but I want to retain the expanded geometry of the stent.

In step 3: I want to crimp this structure again and calculate the stress generated during this step.

For step 2, I have tried using MODEL CHANGE from interaction module to deactivate elements in the step but I am not able to go see stress as 0,instead the model disappears.Can some one help me with this?

In case of restenosis of blood vessel future heart surgery will be simplified as the approach to heart blood vessels will be from surface

We usually administer dual antiplatelet therapy in various combinations to a post PCI patient. Some of them are on chronic anticoagulant therapy for stroke prevention. Some of them may have relatively higher bleeding risk. How do you plan your antiplatelet regime to such patients without compromising bleeding risk and risk of stent thrombosis?

Hello,

I am trying to show if there is any relationship between the different variables (weight, age, risk score) and freedom of re-intervention after a stent placement. Freedom of reinterevntion is a time depending value, so the more I think about it I think I should use cox's regression model. But on the other hand I am thinking weight/age/risk score and freedom of re-intervention are both continuous values so if I want to show a correlation between the two I should use the pearson/spearman? What do you think? Also if I am reporting the cox model, should I just report the hazard values and the p-values or may be more?

Thank you in Advance

According to Dawson and colleagues (2007), some surgical faculty identified some shortcoming of knowledge and skills. Example of these include the choice of catheter, balloon , and stent size. Adequate placing of the sheath was also identified as an issue in training residents.

What do vascular surgical residents struggle most with in their surgical education and training? Do vascular surgical residents and attendings believe that their medical education should be changed from the current standards?

Dawson and colleagues (2007)

https://pubmed.ncbi.nlm.nih.gov/17210400/

We have a projet about valvular stents

One of the major drawbacks of cardiac stents is the placement of the clot inside the cardiac stent

How can these clots be removed?

I successfully completed the simulation for stent. I'm able to find stresses, strain and displacement of an element/node. But how to find the values of elastic recoil, dog-boning and foreshortening for stent?

In a study there are some animal species need to implement a coronary stent from (femoral artery) and to undergo a laparotomy in order to place a telemetric transponder.

What are the recommended anesthetic drugs that induct anesthesia without affecting the cardiovascular system at the time of procedures for equine?

We have a projet about TAVI

Hello there, I am doing Explicit analysis of Three different materials and for one of the material Strain value is coming High as compare to remaining Then what it signifies to me? For best material, considering the elastic strain which one is best ? and how to choose it.

Please explain in details if you know.Thank you in advance

A 42-year-old patient with history of diabetes, hypertension and ischemic heart disease where coronary angiography with stent was done for him before presented to ED with chest pain and fatigue

What is your diagnosis ?

I am working on a project that involves predicting the cost estimate of an Angioplasty and Stent placement procedure. I need to know the variables to put into my model. Would highly appreciate if anybody could give me an idea of what all parameters affect the overall bill. Numbers aren't necessary. Just the categorical split-up will do. Numbers would be great if you have them.

Medical devices cover a wide range of products ranging from eyeglasses to active coronary stent, via wheelchairs. Medical devices are also characterized by a short life in the market, small patient populations and a high potential for innovation. Do you think it is necessary to distinguish different clinical study methods for the authorization of new medical devices to be marketed according to their level of risk?

Hello,

I am modelling a vascular tissue (intima) cut by a sharp instrument in Abaqus. The scheme of my model in on the picture. The instrument will be translated and simultaneously oscillated with ultrasonic frequency. The tissue is cut just below the metal stent struts.

I can figure out the nonlinear properties of my tissue (Mooney-Rivlin coefficients deduced from experimental data of simple tension) and the loading conditions but the problem is - how to define damage properties for soft tissue in Abaqus? More precisely, I want to find out what “material behaviours” in material definition should I introduce except for the "mechanical-elasticity-hyperelastic".

All the "cutting" models I've found use “Johnson-Cook formulation” or “Ductile damage” but I think they are only for metals. “Traction-separations laws” can’t be implemented because they require the predefined crack path and it is not possible because I can’t predict this path.

This problem is more similar with a “bullet impact in gelatin” – the material is damaged by an instrument but the instrument can be translated in course of the impact https://www.sciencedirect.com/science/article/pii/S175161611630412X

I tried to make the research by myself but I still have several questions:

1. As I have the complete test data maybe it is sufficient for damage modelling to indicate elastic and plastic behavior of the tissue?

2. What “material behaviours” would you recommend me to define in this case?

Thank you in advance,

Nikita.

A 54 year old Male underwent Non Anatomical resection for Cholangiocarcinoma involving Seg 5/6 in December 2018. He developed perihepatic collection for which he had undergone percutaneous catheter drainage 3 times. Last drainage was done about 2.5 months back in June 2019. ERCP and CBD stenting done in Feb/March 2019 failed to stop the leak which ranged about 20-25 ml a day. He has no abdominal pain or fever. He has undergone percutaneous transhepatic glue injection on 20th July 2019 as MRI showed a small collection communicating with ductal system on the right side (Segment 7). Post the procedure, the daily discharge has fallen to about 9-10 ml/day. (It has reduced but had not been arrested). What is the appropriate next step to take in this regard to stop the leak ?

I want to develop a material for a cardiovascular stent application. Therefore, I want to know about the pressure which a stent will bear in the artery.

We have many techniques for revascularization [angiplasties, new stents, vascular bypass], yet we are not doing early screening in patients with multiple vascular risk factors.

Should we be more active in our early screening of the carotid and cerebral vessel circulations?

Are we missing the boat?

Clopidogrel is often used to keep coronary stents patent

Clopidogrel resistance can be up to 30% of African/Asian populations

Should we be doing more routine testing for the marker of resistance- CYP 19 in these populations? Otherwise we may be giving placebo to our stent patients...

Basically, biomechanical stent modeling can be divided into three areas. The first area belongs to the modeling related to the mechanical properties of the stent, the checking of the stress states of deformations, the arrangement of the voltage on the wall of the blood vessel, etc. and mainly these tests are based on the Finite Element Method (FEM). It is very important to carry out all the tests at this stage in order to find out all design defects in time, because any irregularity discovered later requires a return to this stage and a re-testing, and this can be a very "expensive" step both materially and temporally. In the second area, the influence of the stent design itself (for example, the shape and layout of the sticks) on the flow of fluid (blood) within the blood vessel is studied and is based on the computational fluid dynamics (CFD), an area belonging to the FEM. In the third area, it is also investigated and tested for the release of the drug in DES stents and its spreading through the bloodstream, penetration into the blood wall.

The objective of the position is to develop a PhD work on the subject “cardiovascular stent design and analysis”. The aim of the work will be to analyze the expansion of the stent and the contact with the artery to simulate thrombectomy technique. The developments will have to be carried out within the Kratos framework.

More info:

I'm working on stents. I simulated crimping process by using 8 rigid plates around the stent. The analysis was successful. Now I want to simulate the dilatation process. I want to remove the rigid plates using 'model change' tool in the interaction module but there's error saying this is not possible with R3D4 elements which is the element type of the rigid plate.

Now what should I do to simulate the analysis.

What is an alternative procedure to define rigid plates?

Young's mod? Value?

Recent developments in potential treatments for metastatic intrahepatic cholangiocarcinoma (both extra- & intra- hepatic metastases) after: Substantial liver resection; standard chemotherapies; multiple surgical removals of affected lymph nodes; maintenance of stent in common bile duct near/at Pancreas; FGFR inhibitor clinical trial; & stereotactic proton beam therapy directed at extrahepatic affected lymph nodes.

I just collect materials of stent insertion for obstructive incurable esophageal cancer. It is retrospectively, so it is difficult to clarify if it's beneficial for relief of dysphagia and a better health-related quality of life. Do you have any good idea to make it useful?

I want to design a 3 fold balloon for stent analysis. Can anyone provide me a step by step guide to it? I'm new to using Abaqus.

I want to compare balloon-expandable stent simulation using elemen type between beam 188 and solid 187 ?

In the solution beam 188, there are option beam tool, and I use direct stress to know the stress in axial direction,

Thus, same for beam 188. I want to know the stress in axial direction in solid 187 element type, but in option stress, there is only stress in the following picture..

can me get the stress in axial direction for solid 187 element type ?

I'm starting to work on stent analysis. For crimping analysis I'm not sure what kind of boundaries will be preferable.(For both pressure controlled and displacement controlled). Also any efficient alternate method to carry out crimping?

Thank you.

The techniques used for oesophagectomy can vary greatly amongst countries, units and surgeons. This is also true for outcomes and historically oesophagectomy has been associated with significant morbidity and mortality. Operative access, anastomostic technique and the treatment of leaks (conservative, stent, endoVac or reoperative) have been continued areas of disagreement amongst oesophago-gastric surgeons and their influence on mortality and morbidity has long been disputed. This audit seeks to provide up to date information in the international variances in practice.

Please complete this Google Form:  https://goo.gl/LzvECw 

Please see attached invitation letter for some further details. 

Can you recommend some material , paper, articles, abput Nitinol Laser cutting for stents fabrication?

I have some doubts about fatigue behavior and the resulting surface.

Hi everyone!

I need to write the history if the stent.

Is there someone who can just give me some papers or research about the stent, its technology and history (from its introduction to evolution/changes and new technologies/applications)?

I would be glad to get in touch, too with some specialists that can give some added value.

Thank you in advance.

Stefania

If dead cells of microorganisms forming a biofilm on a stent, accumulate due to actions of antimicrobials, could they provoke inflamation?

I'm working on a research for the university so i'm wondering does the artery return back the same if we didn't use a stent after inflate a balloon ? and why it's better to udse a stent that made from auxetic material? I know the properties for auxetic materials but what does it have to do with the blood?

Stent Can be coated with drug embedded in a surface polymer. Drug-eluting coronary stents can help prevent plaque buildup, promote good blood flow to your heart, and relieve chest pain. They may also lower your chances of having a heart attack.

I have done the simulation such as:

"The simulative model about the living arteries by stent for various diseases: from expanding to blood flowing to possible fracture "

Key words: Artery stenosis, Stent, Nonlinear Finite Element Method, Bidirectional Fluid-Structure-Interaction, Fracture

BUT I want to an idea for biomechanics or clinical medicine !

Would you give me some advice or cooperation?

drug eluting stents are the second generation of stent that deliver the drugs on the vesseles wall. many research has been done on these stents.

I want to know are these stents available for all of countries or not.

Dear Experts,

Am aware, 400 series of steel possess high strength, high wear and acceptable corrosion resistance. Also, it has been extensively used as Cutting tools for Medical surgeries but why not as an Implant (orthopaedic or stents).

I looked for papers which relates the Bio-response of the cell or platelet adhesion over Martensitic steel ( ex. 420 or 440 ) but i couldn't see any published work explaining the same.

It would be great if someone could help me to understand better or to suggest some more research articles ?

Thank you in advance.

i have used a quasi-linear visco-elastic model. now , i want to test a single cube with one element with a pressure load in tension in different time periods in abaqus explicit .

1-why are the  stress results different in different time periods?

2- why is kinetic energy  so big compared to total energy(50 % of total energy or even more) while i'm not using a dynamic model?

3- why the results change when i use mass scaling?

After performing endoscopic dacrocstorhinostomy (DCR), some surgeons  prefer to put sialastic tubes as stents in the lacrimal system to prevent recurrence an to keep patent nasoacrimal system.

What is the value of using stents after performing endoscopic dacrocstorhinostomy (DCR)?

Some children with post corrosive esophageal stricture are refractory to esophageal dilatation, at which time esophageal stenting many be indicated. 

Please discuss the design and requirement of Mg alloy based stents? Are short stents made of Mg alloys are preferable?

Within the last few years, I experienced three cases of pneumoperitoneum with and without pneumomediastinum developed immediately after the colonic stent implantation in patients with severe malignant colonic stenosis. Despite the presence of pneumoperitoneum, no patients complained about abdominal pain and presented peritoneal irritation. Moreover, there was no evidence of panperitonitis and elevated inflammatory reactions. Oral intake became possible after the deployment of colonic stents. All these patients underwent surgical resection of colon cancers. Operative findings revealed no evidence of colonic perforation. Postoperative course was uneventful. Does anybody have concerns about pneumoperitoneum that develops after the colonic stent implantation in patients with severe malignant colonic stenosis?

Aman of 70 years DM, Hypertension and CAD had CBD partial injury(3/4 of circumference) during a difficult lap chole with frozen callots.No energy source was used.Corners were secured with 4o prolene and an antigrade stenting was attemted with 10 f Amsterdam stent.It was not successful as the division was on the CHD as the flaps were coming out through the defect despite several attepmts to place it.Hence a 12 f T-tube was placed and the CBD was repaired well.No leak of bile post operatively.The recovery of the of the patient was uneventful.Tube drain in the sub hepatic space was removed on 4th post op day and pt was discharged.T-tube out put is around 300mls in 24 hours.

I have been working as a member of a research group in the field of cardiovascular stent. We prepared our 3D-printing stent with a reasonable mesh-like structure. But before any further surface modification, we need to investigate its mechanical properties, and conduct the mechanical testing on our model stent.

I need to know what type of analysis testings we need to be run.

I would be happy to hear your answers.

Your experience of optimum duration for ureteral stenting post augmentation cystoplasty, in the following cinarios, 1) augment without ureter reimplantation, 2) with reimplantation 3) redo augmentation ?

Is there a role for esophageal stenting in late presenter 31 years old female with stable iatrogenic tracheoesophageal fistula prior to ercp 45 days ago. it is 25 cm from the central incisor with a good communication between the esophagus and the bronchus intermedius

This 18 year old girl was detected to have Takayasu arteritis with hypertension during evaluation for polyarthralgias. MR angiography revealed her to have severe renal artery stenosis left and left subclavian artery stenosis. Recent literature seems to suggest a higher failure rate and restenosis with stenting rather than with plain angioplasty. This goes contrary to what we see in atherosclerotic coronary artery disease stents have a higher success rates. 

The choice of the more appropriate method of SFA recanalizazion represents a very interesting and actual topic. This is particularly relevant in claudicant patients. It is reasonable the use  in these cases of a covered Stent  ?

Hello everyone

I want to start my thesis on biodegradable stent modeling. What do you think, would it be useful? Which material do you suggest, magnesium or PLA?

Hi,

Is there any way to know how much radial stiffness the stent should have in order to open the occluded vessel.

Or do you have any other thecnique to share?

Which force is needed to make an implant move/grow through soft tissue? There seems to be a threshold to be overcome by stents (or other implants) to make them grow through tissue. Too low means no growing through. Too high would create lesions. The only reported force I know is from bracelets on the teeth (nearly constant 1-2 N for extraction).

Is there anything known for soft tissue? Ideally for stents in atrial walls? Which biological processes enable this kind of "growing through"? How could i foster it?

I'd be thrilled to hear about your input!

Johannes

Despite of notable results of decreasing restenosis in patients who have used Drug-eluting stents, There are doubts about impact of DESs on thrombosis and death after one year. Is this been proven as a serious issue or it's ignorable?

if a stent Is implanted  into a narrowed part of a vein the question Is if there will be blond coagulation preferable? Is it dependent on the blood system of the individual? What are the duration times for coagulation? 

I prepared chitosan nanoparticles some have got 0.2 and others are in the range of 0.4 - 0.5.

We know that,we use stents to splint or keep the coronary artery open.

There is several types of stent procedure.

So,when we use nitinol stents,and what are its advantages over others?

Bile duct stones: recent studies and meta-analyses demonstrated that there is no advantage in biliary stent positioning after LCBDE with choledochotomy when compared to primary duct closure in elective surgery. Is there any indication for biliary stent positioning in emergency scenarios?

Thank you very much for your contribution.

I want to know which polymers except PLGA, PLA and PEG are used in DES and which drugs help to have lower restenosis. 

In our hospital, we use plastic stents for malignant biliary obstruction, usually it needs to be replaced due to its obstruction.

Due to the nature of the disease, the short life span of the patient, the possible obstruction and the need for replacement and the much more expensive metallic stent... I ask if malignant biliary stricture is worth this very expensive self expanding metallic stent?

I found the the anticoagulation therapy strategy varies with ePTFE material implants in human vessels, such as artificial vascular graft, stent, etc. What are the factors that influence the anticoagulation therapy?

I am researching into hyperperfusion syndrome and prevention, specially in carotid stenting. 

Is there any evidence that a staged procedure is more beneficial than a single stage procedure in severe ICA stenosis (80% or higher)

Have you experienced cases with hyperperfusion syndrome following carotid stenting ?

38 year old non alcoholic diagnosed to have recurrent pain due to chronic tropical pancreatitis underwent PJ(longitudinal) 8 months ago.Relapse of his symptoms in 3to4 months after surgery.Investigations about a month ago showed elevated Amylase and Lipase,CT reported to show dilated distal PD and non visualized duct at the level of PJ.Options mentioned were Endotherapy(pd sphincterotomy,stenting),Revision surgery and coeliac ganglion block.Prior to these a good MRCP,

I'm a doctor in training and and I would like to explore this new type of stent understanding how it works in detail.

Thank you

When a stent is placed in a STEMI patient, and a pre-dilation balloon is used to facilitate crossing the lesion, what is regarded as balloon time in the door to balloon time profile? I have had 2 indicators suggested. For me I see it as pre-dilation balloon catheter withdrawal time, as this now facilitates flow through the lesion, but others have said its the device deployed time, as a result, stent balloon catheter withdrawal time. I need to be uniform in my research variable, so would like to ask what is generally accepted as balloon time?

67 year old woman with a recent H/O Rectal tenesmus, no blood or mucous.Otherwise no other GI findings clinically.Had CAG and stenting 7 years ago. Now upper GI and colonoscopy and biopsy from sigmoid are normal. CECT with contrast showed mild thickening of sigmoid with few diverticula. Uterus and ovaries are atrophic.