Subject: Re: Intra operative vein bypass graft duplex
Author: [log in to unmask] at Internet
Date: 7/17/96 8:03 AM
How does ones one evaluate the elevated velocities which inevitably occur at the
distal anastomosis as large vein is attached to smaller native vessel? This
seems to be a problem particularly with distal bypasses i.e. fem- DP or fem PTA.
University of Vermont
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I know, I know, I've been preaching this stuff for years but here goes again. Is
there a stenosis associated with the flow acceleration? Is a 1.5 mm residual
lumen at the distal end of a 4 mm vein a stenosis at all if the recipient vessel
is 1.5 mm?? Well, yes and no!! I suppose you could argue either way. What they
try to do here is make a long spatulated anastomosis and make it a smooth
transition. If we don't visualize a stenosis intra-operatively, then they would
likely not try to revise it regardless of the velocities. Remember, velocities
may be greatly affected by hyperemia, spasm, etc. Remember Holec's Second Law of
Doppler - A Doppler change is only a Doppler change, it may be a flow change if
you interpret the information correctly, and it may or may not be a stenosis.
All Doppler changes must be explained by imaging! (Holec's First Law of Vascular
In other words Terry, expect that velocity change anywhere you see a dramatic
caliber change. But no hard numbers from here. In our experience, the
variability is high. It varies with C.O., inflow, graft quality and mostly what
the recipient vessel is like. Many of these are calcified, stiff, and diseased.
Also remember Smith's First Law of Surgery - Perfect is often the enemy of
good! Very often a tough call.
Bon Secours Venice Hospital