MikeInFlorida wrote:ttucker wrote:The IVUS measurements under discussion are a potentially direct means of determining any haemodynamic standing pressure waves created by venous obstructions. If such pressure waves can measured by IVUS, then through the application of computational fluid dynamics, the amount of hypertension in the area of periventrical lesions could be computed. If this hypertension is sufficiently acute to cause blood-brain barrier breakdown this would provide an explanation for the transport of iron and leukocytes into the cerebral parenchyma. It would also provide a means to estimate the amount of capillary bed ischemia, hence hypoxia, hence loss of oligodendrocytes and hence deterioration of myelin. Leukocytes meet weakened myelin and - voila - MS. If IVUS pressure waveform measurements (systolic and diastolic would suffice) could to be taken at a number of positions going up the vein (IJV?) with a measure of the distance from the obstruction, this could demonstrate that both neurologists and vascular scientists are right. It is an autoimmune disease, but its root cause lies in the venous obstruction causing acute hypertension in the BBB at the venule end of the bed.
If I understand you correctly, you believe that, not only do venous obstructions increase the static venous pressure, but the resultant turbulence (from reflux) creates standing waves, the period of which could be measured with the IVUS equipment. Then using sophisticated mathematics, these wave parameters could be predicted (or translated into) the DCVs?
I love the standing wave idea, but measuring them in the IJV and using that to calculate the DCV wave freq and amp seems... prone to error (but I'm no expert on this).
Regardless, wouldn't it be great if the measurements could be made in or near the DCVs? I wonder how far into the (e.g. straight) sinuses you can safely put the IVUS, using the smallest available catheter sheath? Dr. Sclafani previously said that the sheath used for this patient was 10 french (3.3 mm)... are smaller sheaths available?
(edited: replaced my misuse of the word "harmonic" with "standing". Harmonic and standing waves are related, but not interchangeable.)
There is a pressure wire for the IVUS. I am not going to explore this until i have mastered the IVUS imaging catheter. Maybe in 2012 if i have some funding.