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Endovascular surgery
Endovascualr surgery
(or coiling aneurysms) involves the insertion of metallic coils into the
aneurysm from the inside of the artery. Via an angiogram a tube (known as a
catheter) is threaded within the arteries of the body and neck into the inside
of the aneurysm. These coils are packed into the aneurysm preventing blood entering
the aneurysm. They also promote clotting of the blood around them. The most
favourable aneurysms to coil are small aneurysms that are rounded with a small
entry from the normal artery into the aneurysm. This is in order to hold the
aneurysm coils within the aneurysm. Some more difficult aneurysms can be
treated by this technique with additional endovascular procedures (such as the
temporary placing of a balloon in the artery to help pack the coils into the
aneurysm, placing a permanent scaffolding stent within the artery to support
the coils, and newer aneurysm coils that promote bonding within the aneurysm.
The risks,
expectations and alternatives of this technique need to be fully understood.
The risks include rupturing the aneurysm during the procedure (the very
complication that the procedure aims to treat and prevent producing the
problems indicated above), unexpected blood clotting within an artery of the
brain (causing a stroke), and re-opening of the aneurysm at a later date
causing a subarachnoid haemorrhage.
Endovascular surgery
(or coiling) is the preferred treatment option for some aneurysms but aneurysms
come in many locations, shapes and sizes and the best treatment requires an
expert to evaluate whether the aneurysm is best treated by this technique,
surgery or just maintained surveillance. In some cases the aneurysm can be
treated with either microsurgical or endovascular technique and the
recommendation as to the preferred technique for a individual needs to take
into account many factors including the age of the patient (for the durability
of the procedure), the skills of the proceduralists (and their track record of
similar aneurysms), the need for progress surveillance angiography, and many
other considerations.
Progress surveillance
digital subtraction angiography is usually performed at 6 months, 12 months and
24 months following initial treatment. Further, follow-up studies may also be
needed depending on the result of ongoing assessment of this treatment. If
re-opening of the aneurysm occurs on these studies there is a risk of
haemorrhage and treatment may need to be repeated or surgery performed.
Microsurgery
Microsurgery aims to repair the aneurysm from the outside of the artery placing
a strong spring clip across where the aneurysm arises from the artery – like
pinching off the neck of a balloon. This prevents blood entering the aneurysm
from the artery. At surgery a small window of bone is removed from the skull
and with the use of the microscope the valleys of the brain are traversed
without the need for cutting into the brain. This gains access to the artery
with the aneurysm allowing the clip to be placed permanently across the neck of
the aneurysm. At the end of the surgery the bone is replaced and secured.
The risks, expectations
and alternatives of this technique need to be fully understood. The risks
include rupturing the aneurysm during the procedure (the very complication that
the procedure aims to treat and prevent producing the problems indicated above)
and inadvertently blocking an artery of the brain.
This is the preferred
treatment option for some aneurysms but aneurysms come in many locations,
shapes and sizes and the best treatment requires an expert to evaluate whether
the aneurysm is best treated by this technique, endovascular coil placement or
just maintained surveillance. In some cases the aneurysm can be treated with
either technique and the recommendation as to the preferred technique for a
individual needs to take into account many things including the age of the
patient (for the durability of the procedure), the skills of the proceduralists
and their track record of similar aneurysms, the need for progress surveillance
angiography, and many other considerations.
It is unusual to
develop another aneurysm at the site of aneurysm repair by microsurgery.
Therefore, progress surveillance is not usually recommended for the treated
aneurysm but because new aneurysms can occur (in as many as 20% of cases) at
other sites ongoing monitoring may be necessary. This may be done by CTA, MRA
or digital subtraction angiography (although the latter is not always thought
necessary).
Treatment by brain bypass
For very complex
aneurysms it is occasionally necessary to perform a bypass surgery to remove
the aneurysmal section of artery from the circulation. This surgery may involve
removing a segment of vein in the leg and substituting this vein into the brain
circulation.
Monitoring
In some cases, no
treatment is warranted either because the risk of aneurysm rupture is so small
that the risks of treatment become too great to consider. In other cases, no
safe treatment is possible. In such people it may be appropriate to monitor the
aneurysm for changes either by MRI, CTA or digital subtraction angiography at
intervals. In the case of small aneurysms that are thought to be at low risk
for bleeding, such monitoring will lead to a change to treatment by surgery or
coiling if the aneurysm changes in size or shape. The need for and method of
monitoring vary from person to person. Although aneurysms can rupture without
any underlying precipitating factors it may well be that very good blood
pressure management and stopping smoking are helpful.
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| Coils inside an aneurysm |
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