Bioabsorbable Stents

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Bioabsorbable Stent

Postby Nunzio » Tue Aug 31, 2010 6:28 am

I found this particularly interesting because it would apply to CCSVI where the age of the patient require very long survival of stents and a bioabsorbable one would be advantageous.
http://inventorspot.com/articles/bioabsorbable_stent_successful_so_far_absorb_25537
For thirty years since the invention of angioplasty, cardiologists have been using stents to repair arteries. First was the balloon stent, then the metal stent, then the drug eluting metal stent. Next it will be the bioabsorbable stent, or should I say now it is the bioabsorbable stent?

Phase I of Abbott's new ABSORB has just been published in The Lancet and the results were very successful. After two years, 30 patients that participated in the trial showed reduction in plaque, no stent thrombosis, no major cardiac events from 6 months to 2 years, and successful absorption of the stent. There was one more result and this one amazed me: the patients' coronary arteries
were virtually restored to normalcy, having regained their ability to contract and expand.

The ABSORB coronary device is made of polylactic acid, a proven biocompatible material that is commonly used in medical implants such as dissolvable sutures. The drug that is eluted by the ABSORB stent is everolimus, an immunosuppressant to prevent the body's rejection of the stent.

Not only is ABSORB the first successful bioabsorbable stent, but the imaging technology that is used to mark its progress is also new, as well as essential to the observability of ABSORB's success. Multislice CT angiography, intravascular ultrasound, and Optical Coherence Tomography (OCT), which were used to measure ABSORB's results, did not exist when stents were first invented.

ABSORB is now going into Phase II trials which will enroll about 80 patients
from European countries, Australia and New Zealand. Drug delivery and vessel support enhancements will be made to the ABSORB stents. It will be at least three years before ABSORB is market-ready.

via PCTA.org
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Postby Donnchadh » Tue Aug 31, 2010 7:55 am

Very interesting....I wonder if the few IR's doing CCSVI would contact the manufacturer requesting it to launch an additional trial for venous applications?
Sounds exactly like what we need. It would be a whole new market for the stent maker, so they would have a financial incentive for seeking approval.

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Postby CureIous » Tue Aug 31, 2010 11:13 am

This is something Zamboni had mentioned last year. It was discussed several times in here, sure is a promising avenue, best of both worlds, stenting, minus the stent so to speak... I'm sure it won't be long.. Hey can I trade my old ones in for these if they come out?? ;)

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Bioabsorbable Stents

Postby jimmylegs » Wed Nov 23, 2011 8:15 pm

Drug-Eluting Bioabsorbable Magnesium Stent (2004)
http://www.ncbi.nlm.nih.gov/pubmed/15546291

update: oooh better link! http://biomed.tamu.edu/biomaterials/bme ... rticle.pdf

Current stent technology is based on the use of permanent implants that remain life long in the vessel wall, far beyond the time required for the prosthesis to accomplish its main goals of sealing dissection and preventing wall recoil.

With the possibility to implant long vessel segments using antiproliferative drugs to prevent restenosis, the practice of transforming the coronary vessels into stiff tubes with a full metal jacket covering all side branches and being unable to adjust to the long-term wall changes, including wall remodeling with lumen ectasia becomes a serious concern.

In this article, we describe the first biodegradable stent based on a magnesium alloy that allows controlled corrosion with release to the vessel wall and the blood stream of a natural body component such as magnesium with beneficial antithrombotic, antiarrhythmic, and antiproliferative properties.

We also discuss the animal experiments and the initial clinical applications in 20 patients with implants below the knee, with final results soon to be released, and the plans for the first coronary study.

The results of these last two studies will indicate whether the absence of a permanent implant and the antiproliferative properties shown in animals are sufficient to prevent the restenotic process in humans or whether the prosthesis must be modified by adding the biodegradable coating with conventional antiproliferative drugs.
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Re: Bioabsorbable Stents

Postby jimmylegs » Thu Nov 24, 2011 6:15 am

Bioabsorbable metal stents for percutaneous treatment of critical recoarctation of the aorta in a newborn (2006)
http://onlinelibrary.wiley.com/doi/10.1 ... 20756/full

Abstract
In neonates and infants with critical aortic coarctation, balloon angioplasty is considered for rescue therapy of heart failure. The use of conventional stents is limited because of further vessel growth, the need of redilation, and later surgical removal. However, a novel bioabsorbable magnesium stent (AMS) might overcome such restrictions of vessel stenting in newborns. Presented is the first use of an AMS for acute treatment of a newborn with severely impaired heart function due to a long segment recoarctation after a complex surgical repair. We hypothesize that bioabsorbable stents will dramatically change the treatment of coarctation and recoarctation in newborns.
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Re: Bioabsorbable Stents

Postby jimmylegs » Thu Nov 24, 2011 6:18 am

Temporary scaffolding of coronary arteries with bioabsorbable magnesium stents: a prospective, non-randomised multicentre trial (2007)
http://www.thelancet.com/journals/lance ... 40-6736(07)60853-8/abstract

Background
Coronary stents improve immediate and late results of balloon angioplasty by tacking up dissections and preventing wall recoil. These goals are achieved within weeks after angioplasty, but with current technology stents permanently remain in the artery, with many limitations including the need for long-term antiplatelet treatment to avoid thrombosis. We report a prospective multicentre clinical trial of coronary implantations of absorbable magnesium stents.

Methods
We enrolled 63 patients (44 men; mean age 61·3 [SD 9·5 years]) in eight centres with single de novo lesions in a native coronary artery in a multicentre, non-randomised prospective study. Follow-up included coronary angiography and intravascular ultrasound at 4 months and clinical assessment at 6 months and 12 months. The primary endpoint was cardiac death, non-fatal myocardial infarction, or clinically driven target lesion revascularisation at 4 months

Findings
71 stents, 10-15 mm in length and 3·0-3·5 mm in diameter, were successfully implanted after pre-dilatation in 63 patients. Diameter stenosis was reduced from 61·5 (SD 13·1%) to 12·6 (5·6%) with an acute gain of 1·41 mm (0·46 mm) and in-stent late loss of 1·08 mm (0·49 mm). The ischaemia-driven target lesion revascularisation rate was 23·8% after 4 months, and the overall target lesion revascularisation rate was 45% after 1 year. No myocardial infarction, subacute or late thrombosis, or death occurred. Angiography at 4 months showed an increased diameter stenosis of 48·4 (17·0%). After serial intravascular ultrasound examinations, only small remnants of the original struts were visible, well embedded into the intima. Neointimal growth and negative remodelling were the main operating mechanisms of restenosis.

Interpretation
This study shows that biodegradable magnesium stents can achieve an immediate angiographic result similar to the result of other metal stents and can be safely degraded after 4 months. Modifications of stent characteristics with prolonged degradation and drug elution are currently in development.
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Re: Bioabsorbable Stents

Postby jimmylegs » Thu Nov 24, 2011 6:23 am

Early- and Long-Term Intravascular Ultrasound and Angiographic Findings After Bioabsorbable Magnesium Stent Implantation in Human Coronary Arteries (2009)
http://www.sciencedirect.com/science/ar ... 9809000697
(full text link)

Objectives
This study aimed to evaluate the degradation rate and long-term vascular responses to the absorbable metal stent (AMS).

Background
The AMS demonstrated feasibility and safety at 4 months in human coronary arteries.

Methods
The PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting) was a prospective, multicenter clinical trial of 63 patients with coronary artery disease who underwent AMS implantation. Angiography and intravascular ultrasound (IVUS) were conducted immediately after AMS deployment and at 4 months. Eight patients who did not require repeat revascularization at 4 months underwent late angiographic and IVUS follow-up from 12 to 28 months.

Results
The AMS was well-expanded upon deployment without immediate recoil. The major contributors for restenosis as detected by IVUS at 4 months were: decrease of external elastic membrane volume (42%), extra-stent neointima (13%), and intra-stent neointima (45%). From 4 months to late follow-up, paired IVUS analysis demonstrated complete stent degradation with durability of the 4-month IVUS indexes. The neointima was reduced by 3.6 ± 5.2 mm3, with an increase in the stent cross sectional area of 0.5 ± 1.0 mm2 (p = NS). The median in-stent minimal lumen diameter was increased from 1.87 to 2.17 mm at long-term follow-up. The median angiographic late loss was reduced from 0.62 to 0.40 mm by quantitative coronary angiography from 4 months to late follow-up.

Conclusions
Intravascular ultrasound imaging supports the safety profile of AMS with degradation at 4 months and maintains durability of the results without any early or late adverse findings. Slower degradation is warranted to provide sufficient radial force to improve long-term patency rates of the AMS.
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Re: Bioabsorbable Stents

Postby Cece » Thu Nov 24, 2011 8:46 am

jimmylegs wrote:Results
The AMS was well-expanded upon deployment without immediate recoil. The major contributors for restenosis as detected by IVUS at 4 months were: decrease of external elastic membrane volume (42%), extra-stent neointima (13%), and intra-stent neointima (45%). From 4 months to late follow-up, paired IVUS analysis demonstrated complete stent degradation with durability of the 4-month IVUS indexes. The neointima was reduced by 3.6 ± 5.2 mm3, with an increase in the stent cross sectional area of 0.5 ± 1.0 mm2 (p = NS). The median in-stent minimal lumen diameter was increased from 1.87 to 2.17 mm at long-term follow-up. The median angiographic late loss was reduced from 0.62 to 0.40 mm by quantitative coronary angiography from 4 months to late follow-up.

So even though it is a biosorbable stent, it is present in the vein long enough that in-stent intimal hyperplasia or intimal hyperplasia at the edges of the stent, where the stent irritates the vein, can happen.

I think the very word 'restenosis' is vague enough to us laymen that it can cause misunderstanding. In this case, it is not a return of the vein to the condition it was before, it is the development of a new stenosis in the same location.

Results could be different in veins than in arteries as well. I think it is well worth further research. Even if it's not perfect, it sounds better than regular stents. And this article has positive results overall.
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Re: Bioabsorbable Stents

Postby hwebb » Thu Nov 24, 2011 12:23 pm

there seems to be a revolution afoot with biosorbable stents...some are designed to last only 90 days:

http://www.dailyherald.com/article/20100909/business/309099830/
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Re: Bioabsorbable Stents

Postby jimmylegs » Thu Nov 24, 2011 2:39 pm

links to before and after diagrams. http://preview.tinyurl.com/6u39ndc

there are some good scans in the full text also.

the issue seems to be that the stents may have degraded too quickly..? will have to read the 90 day article to see if they've found a workaround..
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Re: Bioabsorbable Stents

Postby Cece » Thu Nov 24, 2011 4:57 pm

"For coronary stents, there is an incredible premium on stent performance," said Campbell Rogers, chief scientific officer for J&J's Cordis unit, in a telephone interview. "You need a Ferrari. The bioresorbable stent is a larger, bulkier stent. The likelihood of it being a significant advance for patients and clinicians in coronary use is not great."

This is the first I've heard that the bioresorbables are larger and bulkier. Not sure if that would be a negative for use in the jugulars.
Abbott's main competitors in the stent market are in the early stages of evaluating dissolving devices. Most of their work is in places such as the leg where the larger size of an absorbable stent isn't a problem.

Stress and pressure on the legs can cause metal stents to fracture, making an absorbable device more attractive, said Sean Salmon, vice president and general manager of Minneapolis-based Medtronic's coronary and peripheral division.

Stress and pressure are also presumably greater in the neck, with higher likelihood of fracture.
Ninety days is a nice short length of time, presuming they are effective. One of the problems with stents is that they limit re-treatment options, because of the need to put a stent within a stent or that sort of thing. With resorbables, you wouldn't have that.
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Re: Bioabsorbable Stents

Postby Cece » Thu Mar 08, 2012 6:37 pm

http://www.sirmeeting.org/index.cfm?do= ... s&abs=1732
Biodegradable Self-expanding Stents for the Treatment of Benign Cardia Stricture in a Dog Model

Presented During: Non-vascular Interventions: GI/GU

Mon, 3/26: 8:24 AM - 8:32 AM

Abstract No: 105

Authors: Y. Zhu2, Y. Cheng1

Author(s)

Dr. Ying-Sheng Cheng, MD, PhD - View Disclosure
Shanghai Tenth Hospital of Tongji University
Shanghai, China

Purpose:

To assess the efficacy of a newly designed biodegradable self-expanding stent for the treatment of benign cardia stricture in a canine model versus group that received normal metallic stent insertion.

Materials:

Forty-eight dog models induced by LES circumferential injection of benzyl-dimethyltetradecylammonium chloride (BAC, 4 mmol/L, 16 ml) were randomly divided into a control group (CG; no stent insertion; n=16), a metallic stent group (MSG, n=16) and a biodegradable stent group (BSG, n=12). Metallic stents were retrieved four days after insertion. Lower-esophageal-sphincter pressures (LESP) and the 5-min barium height (5-mBH) were assessed before and immediately after the procedure, and at 1-week, 1-, 3- and 6-month follow-up. Four dogs in each group were sacrificed for histological examination.

Results:

Stent insertion was tolerated by all subjects. At the 6-month follow-up, the values of LESP and 5-mBH in the BSG is more stable compared to those in the MSG (p<0.05). Immunohistochemistry for mouse anti–proliferating cell nuclear antigen (PCNA) and a-smooth muscle actin revealed stronger inflammatory reaction in the BSG than in the MSG (p<0.05). Collagen proliferation was more severe after 6 months in the BSG (p<0.05).

Conclusions:

The novel biodegradable self-expanding stent was more effective than normal metallic stent for the treatment of this benign cardia stricture canine model despite it induced stronger inflammation reaction. Further studies are required to assess if drug-eluting biodegradable stents may reduce inflammation reaction and provide more stable treatment outcomes in a long-term.

Are any of the other reports of biosorbable stents finding that greater inflammation caused by the biosorbable stent? It also says that collagen proliferation was more severe after six months in the biosorbable stent group. We may have collagen abnormalities in our jugulars to begin with so this could be a concern.

This is research in dogs, not in humans, and not on CCSVI. Still found it of potential interest.
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Re: Bioabsorbable Stents

Postby MrSuccess » Thu Mar 08, 2012 9:16 pm

there is a small bioabsorbable stent study being used on people .

I cannot remember exactly who-what-where. Heart patients...

our cardio experts can supply the information.

It's already being tried in people.... no need to off any more dogs... :twisted:


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Re: Bioabsorbable Stents

Postby dania » Thu Mar 08, 2012 10:17 pm

Dr Hernadez who just performed Bi-lateral vein bypss surgery on me thinks that "PERHAPS" the reason people get clots in their stents is that the flow in a vein is slower and has less force than the flow in an artery. He does not think they are a good idea.
Makes sense to me.
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Bioabsorbable Stents ???

Postby MarkW » Fri Mar 09, 2012 2:42 am

I advise all pwMS not to try bioadsorbable stents at the current time. Leading CCSVi practitioners have yet to agree on what and how CCSVI syndrome is best treated in pwMS, even which veins to investigate. Hence it is illogical to consider an untested (on other people) stent in pwMS, until the basics are agreed.
Boring answer I know, but please stay safe in what you do and propose.
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