Subject: Venous Mapping
Author:  [log in to unmask] at Internet
Date:    7/23/96 9:47 PM


Dear FlowNetter`s
 I have some questions regarding the practice of venous mapping in 
other institutions.  We do not do a lot of venous mapping at my hospital 
(I assume most is done by the vascular surgeons in their offices) but 
when we do we are assisited by a radiologist.  We recently did a rather 
long and tedious case of mapping long and short saphenous veins as well 
as mapping a previos graft on a pt. who had suffered a GSW and previous 
fem-pop bypass on his right leg.  
 We wondered about the angle we were insonating at as we mapped 
these veins and how that affects the "accuracy" once the surgeon begins 
to make the incisions.  Is their a standard position in which the leg 
should be placed?  What about cases like this where the pt. could not 
obtain some positions?  Is this mapping usually done by RVT`s only?  If 
so, what about the learning curve as new techs begin to perform these 
procedures?  I would hate to think that pt`s suffer extra incisions 
and/or scarring in the early stages of the learning curve.  
 As you know these can be very time consuming and sometimes it 
does not seem very practical to tie up one of the radiologists for the 
entire exam but we do want what is best for the patient.
 I realize I am probably in the minority by working in a radiology 
dept. rather than a dedicated vascular lab, but hopefully we will get 
there someday.  I look forward to your comments and thank you all in 
advance.
     
Bill Beymer RDMS, RVT
Parkview Memorial Hospital
Ft. Wayne, IN
______________________________ Reply Separator _________________________________

Bill -  You ask some good questions. I was always concerned by the leg position 
issue. It may help to get into sugery to see how the leg is postioned but this 
will also vary with the procedure. Its importance also varies with the 
technique. If mapping an in-situ, it is probably more important to note any 
major branches or bends which can frustrate when using the valvulatome, then the
exact position under the skin which can then be easily determined when 
arterialized and fistulas are ligated. I would advise that you pay attention to 
the transducer angle, try to aim straight down, and at least make sure that its 
not angled too far, usually it will be posterior medial as the GSV heads in that
direction in the thigh.  For reversed vein grafts, the vein is located 
proximally and the incision is generally advanced along the vein by diect 
visualization. Clearly however, leg position is an issue. We have seen some 
rather dramatic shifts in location with different positions. For comfort, 
remember surgeons know the anatomy. 

In terms of the time required, it is generally not prohibitive. You know the 
anatomy, it should be there. If you have THAT MUCH TROUBLE, the vein is very 
likely not adequate to use and you should move on to the lesser saphenous veins,
the contralateral leg, the arms. There is not much use mapping a 1-2 mm 
sclerotic vein or one with significant varicosities. Once I realized that, (it 
only took me 5 years or so), vein mapping got a whole lot easier. Although make 
sure to map any parts of the vein that may be adequate, even if the whole vein 
isn't. Vein segments can be spliced together. We have found that by putting the 
patients' feet (hopefully not foot- ? humor) down, it helps to dialate the vein 
and make it a little easier to see. However, it won't help if the vein isn't 
there or otherwise inadequate. 

How about the big question - anybody yet find the marker that writes on gel???

Bill Schroedter
Venice, Fl.