I have been asked to share my thoughts on renal veins.

The jugular and azygous veins are the veins responsible for CCSVI. In the vast majority of cases this is from a malformed valve. When the flow in these veins is blocked the body has natural alternatives for draining the blood. In the jugular system the thyroidal and external jugular are the major alternative draining veins. The supreme intercostal vein and lumbar veins are the alternative veins for the azygous system. Less commonly the left renal vein provides alternative drainage. When the left renal is an alternative it is almost always in the setting of hemiazygos vein compression.

The important points are A)The renal veins do not directly cause CCSVI. B) The left renal vein is rarely involved with CCSVI, as an alternative. C) the left renal vein drainage is most often seen with hemiazygos vein compression.

Pathology of the left renal vein is quite unusual. Based on my evaluation with IVUS and review of literature it is not associated with a valve problem. Left renal vein abnormalities are caused by compression of the vein. When present it may cause flank pain or blood in urine.

Renal vein abnormalities are rare. I feel safe stating that I have treated as many hemiazygos compressions as anyone. In my experience hemiazygos compression is rare. Finding a patient with hemiazygos compression AND left renal vein compression is like finding the proverbial needle in a haystack!

So how would one identify when the renal vein is play a role, any role in ccsvi. Well first of all it would be evaluated last. What I mean by that is, you evaluate the azygous and hemiazygos veins. You correct any problems found in these veins. After treating the azygos and hemiazygos if you still have left renal drainage it means one thing. Blood is finding it easier to flow in the renal rather than the azygous. Logically one would try and search for the lesion blocking azygos/hemiazygos flow. If not found are able to be corrected I suppose one could make sure the left renal was wide open. Intuitively, this would be known since venous blood always flows in the direction of lowest pressure. The azygos blood draining into the left renal IMPLIES a normal renal.

For the sake of argument that all these rare events all came together in a single patient. Azygos/hemiazygos abnormality that could not be correct and alternative drainage into a left renal...that is abnormal. Well the treatment would be to stent the compressed renal vein. Balloon angioplasty of a compressed vein is not the standard of care for 2011.

So in summary. Renal vein involvement in CCSVI intuitively impossible and if it actually occurs exceedingly rare. If it ever were found it would be discovered after thorough treatment of the azygos/hemiazygos sytem. (renal vein treatment prior to azygos/hemiazygos should not EVER occur). In the off chance all this occurs, treatment of the left renal vein would be using a stent, NOT a balloon.

This is my opinion on renal veins and CCSVI. If another physician has a different opinion. I welcome a rebuttal on this page.