You're talking about the basement when most of us only know the ground
floor (for me, this translates into...arms are nice, legs--sorry, not
that much experience).
Very generally speaking, a significant lesion will usually cause a
>100% increase in PSV when compared to the adjacent, normal segment.
In Radiology, September 1998, Vol 208, #3, 655-661, Robbin et al use a
focal 2 to 2.9 X PSV for 50-74% and a threefold increase for 75% and
above, BUT, this was in the upper extremity.
Other, UPPER extremity articles you might reference:
Silva Berry's 1989, Journal of Vascular Technology, Vol 13, April
1989: "Hemodynamic flow parameters in grafts with adjunctive
Gerald Walter's 1992, Journal of Vascular Technology 16(3),
May/June 1992: Color duplex evaluation of potential hemodialysis
Someone who might be able to help you in greater detail would be Carol
Miranda, RVT, RDMS, RDCS.
My lower extremity, synthetic loop, thigh access graft diagnosis of
the month (a pre-Christmas holiday special by the way) is randomly
pointing somewhere between "more or less" normal and "snow within 6
months"...BUT...why does your vascular surgeon suspect a venous
outflow obstruction (problems with dialysis--vascular surgeon
Hope this has been of some help.