membraneous obstructions

[Cece]

Sometimes membranes are seen on IVUS in our jugular or azygous veins. Membranes can be obstructive but it's been hard to pin down just what a membrane is (as opposed to a valve). Are septums a type of membrane? Anyway I was reading about venous obstruction in the liver veins, since more study has been done on liver veins than on jugular veins, and came across this.

In the intrahepatic inferior vena cava, obstruction may also be caused by a membrane or web. These webs were originally thought to be congenital in origin, but evidence now suggests that they are actually sequelae of thrombosis [17]. One authority now prefers the term “obliterative hepatocavopathy” rather than “membranous obstruction of the inferior vena cava.”

http://www.ajronline.org/content/180/6/1583.short
Following that back to its source article gave this:

Primary thrombosis of the IVC most commonly occurs in its hepatic portion, which seems to be predisposed to thrombosis and has been called membranous obstruction of IVC, because the thrombus organizes into a fibrous and frequently membranous occlusion of the IVC.

http://www.ncbi.nlm.nih.gov/pubmed/11928076
Could some of the membranes seen in CCSVI be the result of old thrombus that reorganized into a fibrous membrane? There is reason to think that pwCCSVI may be at an elevated risk of thrombus. If there is slow flow or stasis in any of our blood vessels, that stasis can promote clotting. Also we heard back in 2009 that Dr. Dake observed that it was more difficult than expected to get his MS patients to an appropriate INR level when on Coumadin.

The question of whether CCSVI is congenital or acquired has not been definitively answered yet. To my dismay, pretty much nothing in CCSVI has been definitively answered.

[1eye]

If people with CCSVI are at greater risk of clots, maybe that's why ballooning can be destructive for some. Certainly it would make closer after-care and monitoring crucial.

The fact that we are using balloons can mislead. The fact that these are rubber does not mean they are soft. A thick-walled, very small balloon filled with liquid is very hard. The arteries or veins are non-existent to a dilating balloon. Of course, doctors know that, and are very careful. But being as hard as they are, balloons are certainly capable of damaging the inside of a vessel. They are being used to intentionally disrupt malformed valves. Damage results in clots if you don't control them.

So we can come full-circle if the clots result in new membranous obstructions. Is this more likely in someone who has them already?

[Cece]

If people with CCSVI are at greater risk of clots, maybe that's why ballooning can be destructive for some. Certainly it would make closer after-care and monitoring crucial.

It's an unanswered question if pwCCSVI are at greater risk of clots but it's been suggested before. Another idea is if you have weak flow in the upper portion of the jugular, that puts you at greater risk of clots when the lower portion of the jugular is ballooned, because it has less flow coming down the pipes.

The fact that we are using balloons can mislead. The fact that these are rubber does not mean they are soft. A thick-walled, very small balloon filled with liquid is very hard.

Some docs are using high-pressure balloons as well.

The arteries or veins are non-existent to a dilating balloon. Of course, doctors know that, and are very careful. But being as hard as they are, balloons are certainly capable of damaging the inside of a vessel.

This, I think, is why sizing is so critical. An undersized balloon will not damage a blood vessel that is larger than the balloon itself. An oversized balloon will. As always IVUS is a good way to get the three-dimensional exact size of the vein, as opposed to two-dimensional measurements taken in the traditional flouroscopy.

They are being used to intentionally disrupt malformed valves. Damage results in clots if you don't control them.

So we can come full-circle if the clots result in new membranous obstructions. Is this more likely in someone who has them already?

Thinking about it more, in CCSVI we're not seeing the clots result in new membraneous obstructions, we're seeing full occlusions and death of that portion of the vein, aren't we? Maybe a membraneous obstruction would be a more likely outcome in the azygous with its more constant flow.