Is my aneurysm suitable for EVAR (keyhole surgery)?
Not every
patient with an abdominal aortic aneurysm (AAA) will be suitable for EVAR (keyhole surgery). Wether you are judged to be suitable
for EVAR or not will depend on a number of factors discussed in more detail below. In my practice around 90% of patients with
a AAA will be found to be suitable for a keyhole procedure. In most UK hospitals, however, this figure is
40 to 60%.
What are the characteristics
of a AAA sutable for EVAR?
For most
centers to be able to consider a AAA suitable for EVAR, 3 criteria must be met:
1.The neck (blue lines in diagram) of the aneurysm which
is the area of normal aorta between the branches to the kidneys and the top of the aneurysm must be at least 1.5 cm long.
This is necessary for the stent-graft to fix in place.
2.The angle (green in diagram) between the normal aorta
above and the aneurysm below must be less than 60%. This means that the aneurysm should be straight rather than 'S' shaped.
The blood vessels going from
the aorta (in this case the AAA) to the groins must be large enough to allow the surgeon to pass the 'packed' stent-graft
throgh them. For most stent-grafts the diameter (yellow lines in diagram) of these vessels needs
to be 8mm or greater.
Only around 40 to 60 % of patients with a AAA
meet these criteria.
How are we able to treat AAA that do
not meet the above criteria?
If the neck is too short we use a stent-graft
that is specifically designed for the patient. This stent-graft (unlike the standard one) will extend above the blood vessels
to the kidneys. It will however have special openings to allow blood to still flow to the kidneys. Similar type of stent-grafts
can also be made to incorporate any important blood vessel that is effected by the aneurysm
We tend to use devices that are better at
dealing with angulated (wonky) aneurysms. There are various techniques that we may use to straighten out the aneurysm
If the access vessels (the blood vessels
going from the AAA to the groins are diseased we use various balloons and stents to widen these and allow us to push up the
packed stent-grafts. If this is not possible, we may put the device in through an artery in the neck.
By using these techniques we are able to treat 90% of our AAA with keyhole surgery.
