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Let's Talk About Stents

Posted: Mon Nov 30, 2009 11:23 am
by zap
OK, post-Radeck stent candidates are asking themselves some hard questions right about now.

I've been digging around trying to get some idea of the safety and durability (patency) of venous stents.

This isn't easy since the jugular stents are a novel application.

At first I researched the stents used in Venous Insufficiency of the legs - in which the Iliac vein is frequently stented - and with very good results. The stents tend to stay in place and not fracture ....
"Patency of iliac vein stents appears good, with primary patency of 75% at 3 years. Close follow-up is mandatory to ensure that stent patency is maintained. Also mandatory is to intervene early in patients with recurrent symptoms that may indicate in-stent restenosis, which occurs in 23% of patients."
Oh, and note that in these cases, the gold standard test seems to be the doppler ultrasound:
"Intravascular ultrasound scanning was routinely performed because transfemoral venography had poor sensitivity for the detection of iliac vein stenosis"
However, the safety record of these stents is thought to be largely due to the location, which is not subject to flexion and external (extrinsic) pressures.

So ... if lower jugular or azygos vein stenoses are in locations not subject to lots of pressure and motion, the safety of iliac vein stenting may be applicable.

But what about the upper jugulars, where it is extremely crowded - and sometimes pinched by bony structures (ie spurs on vertebrate)?

For this I researched subclavian stenting - such as used for venous Thoracic Outlet Syndrome (or 'Paget-Schrötter syndrome').

In this condition, the axillary/subclavian vein is pinched off by bony structures (ie the first rib).

Here I found many references to problems with stents - they wanted to use them since angioplasties don't hold up against the extrinsic pressures, but have found that unless the external pressures are first addressed (by partially removing the first rib to make room in the outlet, for example), the stents can easily fracture or collapse ... especially problematic when we're looking at decades ahead, and since upper jugular stents, unlike Thoracic Outlet Syndrome patients', are not easy to access surgically later ...
"The use of stents alone without first-rib resection, however, appears to be associated with stent fracture."

"Stenting of the axillary/ subclavian vein as a modality of treatment for this condition is contraindicated 5. Many patients that develop this syndrome have an underlying narrowing of the thoracic outlet (osseous or fibromuscular). A stent inserted under these conditions may not deploy properly because of the external compression and may induce further thrombosis and therefore further compromising the already tenuous venous outflow."


"Most authors do not recommend stent placement without surgical decompression (rib removal) because the stent itself may be compressed or become fragmented by the thoracic outlet narrowing. Dowling et al reported a case of venous thoracic outlet syndrome treated with thrombolysis, angioplasty, and stent placement without immediate first-rib resection. The case was later complicated by stent fracture.31 Meier et al reported a series of 6 patients who underwent venous stent placements immediately after thrombolysis for venous thoracic outlet syndrome and 2 patients who underwent delayed stent procedures. Two of the 6 patients who underwent immediate stent placement did not undergo immediate surgical rib resection, and both patients had the complication of stent fracture. Long-term (1-3 y) patency was achieved in 6 of the 8 patients.32 "

"In summary, stenting and stent-grafting of the lateral segment of the subclavian vessels where the clavicle crosses the first rib may be associated with stent fracture. This seems to affect all types of devices, including covered stents. Future device development should focus on materials capable of withstanding repeated deformation to improve long-term results. In the interim, resection of the first rib may help to prevent this sequela, although it is an unproven strategy. Until this problem is solved, stenting of this portion of the subclavian vessels should be undertaken with caution."
Finally - and I found this important given the images I have seen of stented veins in constricted upper jugular spaces:
Finally, proper expansion of a stent after deployment must always be verified with radiography on fluoroscopy in different projections. The radial strength of the stent is greatest when it is expanded in a circular form. If it is expanded ovally, the stent is more prone to collapse by two-point compression forces.
(from http://www.ajronline.org/cgi/reprint/160/5/1123.pdf)

Further reading:

Subclavian Stents and Stent-Grafts: Cause for Concern?


Thoughts?

Posted: Mon Nov 30, 2009 11:45 am
by zap
Does anyone have images of the stented areas in different head positions? (bent forward, back, sideways)?

I am not really sure how much "repeated deformation" these stents will be subject to ...

Posted: Mon Nov 30, 2009 11:49 am
by MS_mama
I think another concern is metal allergy as a lot of people are allergic to nickel. Are there stents with alternative materials?

Posted: Mon Nov 30, 2009 12:06 pm
by cah
MS_mama wrote:I think another concern is metal allergy as a lot of people are allergic to nickel. Are there stents with alternative materials?
This was discussed in the german forum. Dr. Simka sais that allergies are not an issue since stents are absolutely nickel free.

zap, in the polish documentary they show how flexible a stent is:

(at 4:30)
Also mandatory is to intervene early in patients with recurrent symptoms that may indicate in-stent restenosis, which occurs in 23% of patients.
23% restenosis doesn't sound that good...?

Posted: Mon Nov 30, 2009 12:10 pm
by zap
I believe that the re-stenosis of Iliac veins is due to thrombotic disease, which is why they had stenoses in the first place ... in our cases, I do not think this will be an issue.

Yes, the stents are flexible ... but when repeatedly flexed in the body, they don't always keep springing back it seems.

Posted: Mon Nov 30, 2009 1:20 pm
by zap
Oh yeah, also meant to include a link to this - a patient with a 3-year old iliac vein stent that fractured and the pieces had to be removed from his heart via open heart surgery - the stent was thought to have been fractured by rolfing/deep tissue massage.

http://www.find-health-articles.com/rec ... ration.htm

So even years later, care must be taken ... (I wince thinking of Loobie poking at his fresh stent!)

Posted: Mon Nov 30, 2009 1:43 pm
by Loobie
I should probably stop that!! It's like a scab though...

Posted: Mon Nov 30, 2009 2:04 pm
by Lyon
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Posted: Mon Nov 30, 2009 4:20 pm
by Brainteaser
bob,

As you know, I'm not exactly your greatest fan. I wouldn't go as far as to call you 'a wanker' which in Aussie parlance is usually reserved for a pretentious buffoon, said with a degree of hilarity............however you do have me wondering at times. :roll:

To me, your most defining characteristic is that you tend to raise a lot more questions than you solve or even try to solve. I'm wondering if 'bob' is perhaps short for 'discombobulation'.

However, even I have to begrudgingly agree that at times you do raise some notable points. The issues you raise regarding the appropriate use of stents are good ones.

But just to prove to me that you are not just hot air, maybe you could investigate this issue a little further in a proactive way. I can't see that you have any real plan to get the answers to the questions you raise, but my suggestion would be that you contact the 4 people who might know something about stents in CCSVI and seek their responses viz. Dake, Zamboni, Simka and Ludyga........and anyone else you can think of or any other action which might move us forward on this. Maybe this could become you personal mission on ThisIsMS - 'Solving the Stent Crisis!'. There you are - I'm throwing down the gauntlet!

Go for it bob!
Phil :)

PS I'm back from Poland with my stent in place, in case you were wondering - SFSG.

Posted: Mon Nov 30, 2009 4:26 pm
by Lyon
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Posted: Mon Nov 30, 2009 4:51 pm
by Brainteaser
Good, incisive response, bob - racism and toilet humour!! :roll:

Posted: Mon Nov 30, 2009 5:00 pm
by mrhodes40
Bob I thought those were good observations also. It could be that open surgery is best for some of these...I wish that something like that had been available honestly. My accsssory nerve deal is a bummer still.

but be that as it may the fact that MS patients have an utter variety of stenoses is really interesting. That bony picture is so different from Alex's or Sammy's pinched jugs (research thread bottom links).

but stent fracture later!--boy that would be very bad news

Let's hope the work goes forward fast enough that other practitioners get on board and we can see the right person for the individual issue.

Posted: Mon Nov 30, 2009 5:06 pm
by cheerleader
So, anyway...before this devolves any further, (sorry, Phil- so glad you saw Dr. Simka!!!)
That's a pic of Joel from Michigan, Bob. He wrote to me thru the CCSVI facebook page, because he'd been referred by friends who had found the site for him. He doesn't have an MS dx, but he has missing jugulars.

I sent Joel to Dr. Haacke ....no one every suggested stenting for Joel. I agree, it's important to know what is going on in the surrounding area of stenosis. You do not want to stent up against bone. Joel had a CT scan. Jeff has had one, and there are no bones, only tight musculature/lumen in his neck on the outside of his jugulars which pressed it in. The doctors try to ascertain what it going on in each individual case. We've seen double valves, cysts, malformations, and now for Joel (and potentially Marc) we see bones. Each MS patient will have a different cause. The common thread is reflux into the brain due to stenosis.

cheer

Posted: Mon Nov 30, 2009 5:06 pm
by Lyon
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Posted: Mon Nov 30, 2009 5:26 pm
by Brainteaser
bob, I'd be peeved if my stent didn't take - that's about all. :cry:

Just having a bit of fun, Cheer - nothing too serious with old bob (I hope). He's always good for a laugh! :wink:

The challenge is still there bob - go for it, mate!!:D

Phil