What is the first thing you should do before scanning grafts?
Need to see if the ABI's are low which may signify that the graft may be failing.
When should you really be careful when get ABI's for testing of grafts?
What should you do?
when patient has had a:
- Femorotibial (Fem-Tib)
Need to check surgical report to see where it is attached before getting ABI on that side.
What are two types of Bypass grafts?
1.) RSVG - Reverse Saphenous Vein Graft
2.) In Situ Vein Graft
What is the advantage of using RSVGs?
Don't have to do anything with the valves because the greater saphenous vein is taken out and reversed 180 degrees so the valves don't interfere with blood flow.
What are 3 disadvantage of using RSVGs?
1.) Small end to largest part of the artery could create a stenosis more easily because of mismatch in sizing.
2.) Must tie off all perforators from GSV
3.) RSVG's and prosthetic grafts may also lie in a subcuteous position but are often placed more deeply.
What are two other ways to make grafts?
1.) Gortex grafts - PTFE
2.) Harvested veins from cadavers
What is the procedure for In Situ Vein Graft? (2 things)
1.) Vein stays in place
2.) Use a valvulotome- device to remove valves from veins.
What is the device called that removes valves from veins?
What does the term autogenous mean?
using own vessels to create access grafts
What is the term that means "using own vessels to create access grafts"?
When grafts are placed in the upper extremity, where are they placed?
And bypassed into what?
Why are they used?
found only usually in proximal subclavian usually left.
Bypass into Lt. CCA
Done only with symptoms or if occlusion occurs.
Are grafts placed in the upper extremity rare?
Yes they are rare. They are only used when symptoms or if occlusion occurs.
What should you do when scanning a bypass graft? (4)
1.) Scan post-op before leaving hospital
2.) Identify the type of graft from patient history/chart/previous reports.
3.) Determine how long the patient has had the graft.
4.) Determine the location of the graft
Where should you get velocity readings when duplexing bypass grafts? (6)
1.) proximal native vessels
2.) right at proximal anastomosis site (inflow)
3.) throughout graft area (prox, mid, dist)
4.) distal anastomosis site (outflow)
5.) distal native vessels
Where is the most common place for stenosis to form within bypass grafts?
What is an important fact to remember about velocities in bypass grafts?
So do what?
-Velocities will decrease if the graft is going to fail.
Look at a prior exam to compare it to the current exam for velocities.
What should you look for in duplexing bypass grafts?
1.) PSV changes
2.) stenosis in anastomosis sites
3.) thrombus formation
4.) Mosacic pattern at anastmosis
What term means "where the graft is connected"?
How often should you scan bypass grafts after they been put in?
What are 4 warning signs of problems with a failing graft?
1.) A decrease of >.15 index is pending graft failure.
2.) A change of a Tri to Bi waveform is a warning sign
3.) A decrease PSV in smallest graft diameter.
4.) If the AV fistulas left might get bigger=A perforator not tied off.
What are 5 possible treatments of failing bypass grafts?
2.) angioplasty or stenting in graft
3.) If failed in 1 or 2 days = Thrombolytic
4.) If failed in a few days = Catheter
5.) If failed longer period of time = permanent damage/failure.