Chapter 14- Arterial Duplex Following Intervention Flashcards
What is bypass grafting used for?
used to route blood around an occluded segment of an artery
Aorta-bifermoral bypass grafts are often seen in patients with what type of disease?
iliac occlusion or disease. The graft is seen from the aorta to the common femoral arteries.
The femoral-popliteal bypass grafts are often seen in patients with what type of disease?
Superficial femoral artery occlusion. It is seen from the femoral to the popliteal artery.
What is the difference between an anatomyic and extra-anatomic bypass graft?
The anatomic one follows the course of the normal anatomy such as a Femoral-Pop graft routes blood from the CFA to the popliteal artery.
An extra anatomic one is placed where vessels don’t typically run such as -one CFA to the contra-lateral leg to treat iliac artery occlusion.
What is another name for a synthetic bypass graft? What is it’s sonographic appearance?
Dacron
Double wall appearance.
What is an autogenous vein graft?
A graft using the patient’s own vein or artery as a conduit/passage.
What are the two types of autogenous vein grafts?
In-situ saphenous vein graft and reversed saphenous vein graft
Explain the process of the in-situ saphenous vein graft.
The vein remains in its place with the large end remaining proximal and the small end remaining distal
The valves are destroyed using an instrument and tributaries are ligated.
Explain the process of a reversed saphenous vein graft?
Unlike the in-situ vein graft (vein stays in place)
the vein is removed and reversed, where the large part is now distal. The vein valves stay open due to the arterial pressure (in situ, they destroy them). The tributaries are ligated.
What is the main difference between the reversed saph vein graft and the in-situ graft?
in the “in-situ” the valves are destroyed verses the reversed they keep them.
What are 3 indications of which we would evaluate a bypass graft?
1) post op surveillance
2) loss of pulse
3) decrease in ABI
What is the most common site of stenoisis in a vein graft patient?
Any retained valves that were not destroyed
What is a common effect from having in-situ bypass?
IMPORTANT
If the tributaries are ligated, they may become arteriovenous fistulas.
What is a common site for stenosis in a synthetic graft?
Anastomoses
What are some things we should be observing for in a bypass graft?
Changes in waveform, retained valves (AF fistulas), graft occlusion,
What is the process of angioplasty with/without stent?
A balloon catheter is passed into the artery and within the stenosis. The balloon inflates opening the artery lumen, then deflated and removed.
Often a metal wire mesh stent is expanded in the area of stenosis to hold the artery lumen open.
Post angioplasty evaluation is important.
What kind of velocities should you expect to see when scanning within the stent?
higher/lower?
uniformly higher through the stent
Will these angioplasty stents show up hyperechoic or hypoechoic on ultrasound?
hypoechoic
What type of waveform should be looking for when scanning within angioplasty stents?
focal flow acceleration or post-stenotic turbulence.
What kind of invasive treatment is done for aneurysms?
Endovascular aneurysm repair (EVAR)
Explain the process of an endovascular aneurysm repair graft.
A catheter is used to position a graft and hooked into place by the stents.
The aneurysm is NOT REMOVED, just simply excluded from the main artery (graft is placed within the native artery)
What is a common complication of EVAR (endovascular aneurysm repairs)
Endoleaks which is persistent flow outside of the graft and within the aneurysmal sac.
Where will we most likely see an EVAR aneurysm graft?
in the aorta
How often will we surveillance these EVAR grafts for endoleaks?
the rest of their life.
OVER TIME, THE SIZE OF THE ANEURYSM SAC SHOULD DECREASED.
If we see an enlarged sac, what should we be thinking?
Endoleak endoleak ENDOLEAK!!!
There are multiple types of endoleaks.
Describe Endoleak Type 1
leak from attachment site.
1a PROXIMAL
1b DISTAL
There are multiple types of endoleaks.
Describe Endoleak Type 2
Patent branch with retrograde flow into the aneurysm
There are multiple types of endoleaks.
Describe Endoleak Type 3
Graft defect
There are multiple types of endoleaks.
Describe Endoleak Type 4
Graft porosity flow through the wall of the material
There are multiple types of endoleaks.
Describe Endoleak Type 5 *IMPORTANT
Endotension - enlarging aneurysmal sac with no detectable leak
We are able to look within the EVAR stent using INTRAVASCULAR ultrasound (IVUS)
Explain this process and what indications we’d have to do this.
Tiny US transducer is at tip of catheter letting us look inside out the stent.
This can help us evaluate for plaque at wall, correct placement of stent, identify if we see dissection.
