Oh, Radeck?

A forum to discuss Chronic Cerebrospinal Venous Insufficiency and its relationship to Multiple Sclerosis.

Longevity of stents

Postby Dovechick » Fri Dec 11, 2009 10:57 am

Radek, I understand your concern and your questions, you have been through a traumatic and unexpected experience which has thrown everything up in the air.
My personal opinion is that each one of us has to asses the risks, in light of your experience undoubtedly but also in view of each person's actual health status now and in the near future. Some of us have more to gain than to loose in spite of the known and unknown risks. In the case of my daughter it is a matter of life and death. She is one of those people who could not live in a totally incapacitated manner and the speed of her deterioration in the past couple of years indicates that his might happen in at most 4 years. So her options are either prolonging her useful life by taking a chance on stenting or doing nothing and buying a one way ticket to Switzerland (Dignitas) in 4 years time.
I hope for all our sakes that you get the answers you need and that you make a good recovery in the short term and some signigicant improvements in the longer term which will make all this unexpected and distressing experience worthwhile.
Michele,  warrior4MS, mother and champion for Ella, the MSer. The solution is out there we just have to ask the right questions.
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Postby ozarkcanoer » Fri Dec 11, 2009 11:53 am

Radek, You more than anyone else here have the strongest reason for asking these questions. It would be nice to have a consensus opinion from a vascular group that would give us all perspective on this. Surely Dr Dake realizes this. Maybe something will come from Dr Dake's upcoming clinical study. I would expect that other interventional radiologists and vascular specialists will participate in this clinical study and not just Dr Dake. No doubt Dr Dake is a wonderful doctor. But some other viewpoints and cautions are welcome too (unless they are NO NO NO, LOL).

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Postby skydog » Sat Dec 12, 2009 10:15 am

Some thoughts I had on the patency of stents. Stents in the arteries are under constant flexing while veins are not. The longer the stent is in place in a vein the less movement would be expected as the contour of the vein takes on more or lees the contour of the stent. There still exists the possibility of greater movement say in the neck area but sure seems as though that the stent will be flexed well within a range that will not cause metal fatigue. I would like to see some of the manufactures data on their products and to what point will they flex before the metal actually fatigues. IMO the stents are way tougher than I and will withstand any punishment that I could give them. Peace, Mark
Last edited by skydog on Sat Dec 12, 2009 1:09 pm, edited 1 time in total.
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Metal Fatigue

Postby Dovechick » Sat Dec 12, 2009 10:35 am

Skydog, I agree, these things are designed to cope with the constant pulsing of arteries, which is probably more movement than the flexing and turning of the head.
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Postby SammyJo » Sun Dec 13, 2009 12:25 am

I looked for safety data on the stent I have. Found a 9 month trial (link) start 4/09, for the Iliac Artery, of the Absolute Pro Peripheral Self-Expanding Stent System, made by Abbott Vascular. One of the many Secondary Outcome Measures is stent patency and restenosis. Did not see any terms that implied migration.

Here is a completed 2008 study (link)that tested several brands of stents in the femoral artery that takes lots of pressure from walking/standing, with low rates in Absolute (3%) while others ranged from 50-100% fracture.

That is all I've found so far on safety, searched on: self-expanding nitinol stents.
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Postby Johnson » Sun Dec 13, 2009 12:32 am

I wonder about the idea of putting a temporary "filter" in the Vena Cava as a prophylaxis against stent migration, and pulmonary embolism from clots Perhaps this ought to be a SOP until more safety data are revealed.
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Postby radeck » Sun Dec 13, 2009 1:13 pm

patientx, I understood the concern about mobility in the jugulars to not only have to do with fracture causing thrombosis, but also clots/thrombosis forming at the transition between stented and unstented vein, which could become welted because of the different elasticities. I think collapsing of the kinds of stents used in us is unlikely, which is also what makes them difficult/impossible to remove after placement, unfortunately.

Mark, I don't know whether fractures of stents happen because of fatigue of the alloys, or only because of high instantaneous forces. I hope only the latter. It's not obvious to me that arterial pulsing has more long term effect than neck movement.

I found one somewhat interesting news article about the possibility of replacing stented vein segments, if it ever becomes necessary. Not sure how far this technology has come.
Last edited by radeck on Sun Dec 13, 2009 1:42 pm, edited 2 times in total.
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Postby cah » Sun Dec 13, 2009 1:37 pm

Hello radeck, just didn't notice that there's a post in my inbox... never used it yet! I will reply to you per email.
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Postby skydog » Sun Dec 13, 2009 1:51 pm

The point I was trying to make is that the spring tensile strength of the stents seem to be quite high and in order to fracture one it must undergo significant bending beyond its normal flex capability. Day in and out movement is not likely to produce such force. Given that they are now encased in a bundle of muscle/tissue it would seem that it would take quite some force to break/fracture one. As for thrombosis to occur there must be a significant inflammatory issue. You do have some very valid concerns to the edges of the stented area causing thrombosis, and also clots/thrombosis forming at the transition between stented and unstented vein. This will remain to be seen over the long haul. I would think that as the stents are incorporated into the vain so will the edges soften or smooth to some degree. Just my hopeful opinion. Cheers, Mark
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Postby CNClear » Mon Dec 14, 2009 3:54 pm

Did anyone get to hold one of the stents? I did, and when I squeezed it, it sprung right back to its original shape and it seemed pretty indestructible given where it would be going...maybe some people have more 'acid' (or something similiar) in their systems that tends to break down the stent strength...When I squished it together, as if mimicking a vein collapsing, it gave in, but not all that easily, However, Dake expressed concern that he didn't know if a stent could even keep the vein open! So, there must be more pressure in there, once it is put in place, than I thought.

My left jug looks like it is totally flat, like a linguini noodle, and shreds into 3 tiny veins that end in little 'cul de sacs' (not a bunch of collaterals, like you would think) and then just peters out where my jaw bone and ear meet. Dake wasn't even sure if there was enough of a vein present that would hold a stent. From what I understood him to say, he would have to put a very long stent in; that seems like it would lessen the ability to move around, for what that's worth...

I asked if he thought there might not be a solution to the basically 'missing' jug on the left and he said, "No, I'm confident I could figure out something." So, he needs to cogitate on that a while, I suppose...but guess that means that angioplasty isn't an option...

and my right one, which looks quite big and straight, he thinks may have a valve problem, because there is a 'detour' collateral vein that starts on one side of the valve and then connects back in on the other side of the valve...Dake kept calling it a 'bucket handle.' He said he would have to do a venography to video the flow and test the back pressure before he could say definitively what, if anything, was wrong with it.

He mentioned doing a 'duplex' test, also. I didn't want to interupt him to ask what that was and then I forgot to ask later...anyone know what a 'duplex' test is? Duplex in telephony means goes both ways at the same time, but not sure how that translates to veins...

He said 'theoretically' you only need one good jugular...and I said, "theoretically, it wasn't supposed to matter either way, right? Isn't current thinking that even bad jugulars would make collateral veins to make up the difference" He answered, "well, yeah, that's right..." So, what then? Are all bets are off until we can study the whole gamut of consequences, or what??

I could post my images from the MRV, but I can't figure out how to correctly, do this...maybe someone can tell me a way to do this?

As for the transition area of stent and vein, I, too, think once it was covered in endothelials, it would be real smooth all around...

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Postby CureIous » Mon Dec 14, 2009 4:09 pm

He's probably talking color duplex doppler aka ultrasound. Your situation is pretty unique, I'm very glad he has some extra time to chew on it, consult on it and come up with the best solution. Those metals are fascinating in their engineering.

Just as an aside, due to the intense scrutiny coming from other areas of the medical world, including ones local to the Palo Alto area (just keeping this less "keyworded"), and out of deference to our favorite IR doctor, and not wanting to post up images that can be scrutinized by others with less than noble purposes, I've pulled down any and all pics from my MRV on my thread. They're still up on my imageevent but nobody's looking there. I'll toss a wink wink in there as to my reasons for doing such, and would recommend we consider doing likewise (only for the time being) so as not to provide certain less than noble individuals with ANY ammunition thats not their's to use. That's just me trying to say it without saying it.

Believe me I can't WAIT to put up all my pretty pics from my venography but will wait until it's no longer an issue.

Mark.
RRMS Dx'd 2007, first episode 2004. Bilateral stent placement, 3 on left, 1 stent on right, at Stanford August 2009. Watch my operation video: http://www.youtube.com/watch?v=cwc6QlLVtko, Virtually symptom free since, no relap
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Postby Sharon » Mon Dec 14, 2009 4:26 pm

Mark -

I did not post my images for many of the same reasons you have taken yours down. We just do not know who is lurking around the Internet -- I would not want someone using my images to make a negative case study of their own.

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Postby CNClear » Mon Dec 14, 2009 4:47 pm

You both make good points...isn't it a shame, though...(guess I'll keep my images to myself, too...)

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Postby Rokkit » Mon Dec 14, 2009 8:41 pm

CNClear wrote:Did anyone get to hold one of the stents? I did, and when I squeezed it, it sprung right back to its original shape and it seemed pretty indestructible given where it would be going...

I'm pretty sure Loobie said he stomped on one. :D
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Postby CureIous » Mon Dec 14, 2009 10:48 pm

Rokkit wrote:
CNClear wrote:Did anyone get to hold one of the stents? I did, and when I squeezed it, it sprung right back to its original shape and it seemed pretty indestructible given where it would be going...

I'm pretty sure Loobie said he stomped on one. :D


Yes, that is the property of memory metal. I've taken some of that stuff at work and heated it up with a cutting torch to red hot, it is very hard to change the properties of it, it always bounces back, just incredible stuff. But I'm not so sure when we talk of strictly tensile strength, that that is the only consideration here. Do I think they will fracture installed in veins, considering the amount of external stresses (vs. internal which is mostly the considerations of arterial stents) ? No, I don't really think they will, even after being placed in a dynamic spot such as the neck, which gets (especially around the jaw area) a good amount of flexion and extension and movement in general, however, Radeck does make a good point of (and this is easy enough to envision), the edges causing welting and abrasion in general, which may or may not be deleterious to maintaining an uncompromised endothelial lining and could result in "callused" type skin forming at the interstitial (my fav. word) between man and machine.

Point being that these are VERY much unknowns at this point, and we DO need to keep in mind that these very stents are basically off-label at this point. I don't have to guess that there is nothing on the package that says, "approved for jugular use only". Yes that is bascially a spurious argument, in light of the fact that there are plenty of devices and especially medications that are used off-label, LDN being a prime example. Heck my GI doc when I had all that weird non-GI related nerve stuff going on last year related to bone spurs in my thoracic spine, prescribed a psychotropic drug of some form or another (can't recall but believe was an SSRI), with words to the effect of, "I know this is normally prescribed for xyz purposes, but take it anyway as it may help alleviate some of your symptoms" or words to that effect. Yeah it helped a little bit, and the problem was actually bone spurs in my middle back due to an old injury, which he couldn't have known at the time, point being of course, "this kind of off label usage for various drugs and/or devices happens all the time".

The problem of course begins if serious side effects begin to be noted, then the FDA or whoever gets involved. The prevalence of off label usage of various medications is so prevalent, it hardly warrants gasps of shock and incredulity. Wiki: http://en.wikipedia.org/wiki/Off-label_use

Of course we are talking medical devices here and not drugs. http://www.orthosupersite.com/view.asp?rID=41242

There's no "gotcha" here, since we aren't putting venous stents into fingers and calling them "finger braces" to exaggerate the example. They're still going in veins, but whether the specific ones used are "specifically made for jugular veins", can be argued as being irrelevant, for obvious reasons, a vein is a vein is a vein.
The devices in question are FDA approved. That's important here. Non-FDA used off label can get you in trouble.

I'd call your attention to this paragraph in the article linked above:

Remember, you are not allowed to use a non-FDA approved product without further regulatory approval and … you are not allowed to use any devices on or off label when your primary interest is to test a hypothesis or obtain generalized results unless you have an appropriately approved research protocol. That is a study. That is different,” he noted.

That's some food for thought....
RRMS Dx'd 2007, first episode 2004. Bilateral stent placement, 3 on left, 1 stent on right, at Stanford August 2009. Watch my operation video: http://www.youtube.com/watch?v=cwc6QlLVtko, Virtually symptom free since, no relap
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