Average azygos venous blood flow in the MS population was found to be 2.87
ml/sec (SD = 1.27) at the upper level and 2.01 ml/sec (SD=1.3) at lower level.
Controls had at the upper level an average blood flow of 2.51 ml/sec (SD = 1.24)
in the azygos vein which is similar to those seen in previous studies [4,5].
Patients with RR-MS had an average blood flow of 2.97 ml/sec, SP-MS blood flow
average 2.65 ml/sec and PP-MS average blood flow of 2.76 ml/sec.
It is interesting that in the MS patients, the azygous flow was higher in the upper azygous by the arch and lower at the lower level. I wonder if that is a normal occurrence in the controls as well or if that could be indicative of a slowing down of the flow as it passes through the azygous in the MS patients? But not statistically significant.
It would be helpful to be able to sort out the MS patients with confirmed azygous stenoses (as found during angiography) from those without it. Clinics such as Dr. Ponec's and Dr. Arata's, that are doing pre-procedure MRIs, must have the data to work with. Perhaps we'll see it presented at next year's ISNVD! Then the MS patients with known azygous disease could be compared to the healthy controls, and maybe then any difference would be more pronounced.
Let me look at this:
Blood flow was measured at two levels in the
azygos: one at the upper level immediately below the arch and the other at a lower
Azygous stenoses are often found in the arch. I wonder if the flow measurement could have been taken at the peak of the arch, and if that would have impacted the findings?
I am a layman, and this is difficult material to work through. I hope not to misrepresent anything.
For the pinching tube analogy, if the flow is the same even when pinched, that begs the question of if it is structure that matters or if it is the flow that matters. Does a structural abnormality in the absence of a flow abnormality have an effect, and would treating it change anything?
My own azygous was extra-large with rapid flow. Dr. Sclafani's assessment was that it was taking flow that was coming down the vertebral veins and vertebral plexus instead of being able to travel down the jugulars, which were nearly entirely blocked. Perhaps I would have been discarded as an outlier, if my MRIs had been in this study.
One of the questions raised in this thread was whether or not the MRI is an effective method of measuring the rate of blood flow through the azygos veins, as stated in the first line of the conclusions of Dr. Tai's research. The azygous is a small vein, and there must be an effect from mediastinal movement, even if shielding is used? I am checking google scholar. It is as always an understudied vein.