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Endovascular (Embolization) Treatment of Aneurysms

 

What is the Endovascular treatment of aneurysms?


Coil embolization is an alternative to surgery. This treatment has been offered at Toronto Western Hospital since 1992. This is done in the Neuroangiography suite under fluoroscopy. The Neurointerventional radiologist will make a small incision in the groin through which a tiny catheter is guided through the femoral artery into the brain vessels. The catheter is carefully guided into the aneurysm. Soft platinum coils are deposited through the microcatheter into the aneurysm. When in position, the coil is released by an application of a very low voltage current causing the coil to detach from the pusher wire.

The softness of the platinum allows the coil to conform to the often irregular shape of an
aneurysm. An average of 5-6 coils are required to completely pack an aneurysm. The goal of
this treatment is to prevent blood flow into the aneurysm sac by filling the aneurysm with coils and thrombus. This should prevent aneurysm bleeding or re-bleeding.

Embolization does not repair areas of the brain already injured.

The patient will be admitted either the night prior or the morning of the procedure. The treatment is done under a general anaesthetic. A minimum 2-night stay is required after the procedure.


1.  a small incision is made in the groin through which a tiny
catheter is guided through an artery into the brain vessels.
2.  the catheter is carefully guided
into the aneurysm.
3.   soft platinum coils are deposited
through the microcatheter into
the aneurysm.
4.  the coils conform to the often irregular shape of an aneurysm. An avg. of 5-6 coils are required for each
aneurysm.
5.  coils will prevent
blood flow into
the aneurysm.

 

The Procedure


Embolization is not an open surgical procedure and requires specialized training. Most endovascular therapists are neuroradiologists or neurosurgeons who have completed training (ranging from one to two years) in endovascular techniques after their medical (five years) and speciality training (five to seven years).

Before admission
Preadmission will be done one day or two prior to the embolization and routine blood tests may be done. After midnight, no food or drink is allowed.

The Day of the Procedure 
After midnight, no food or drink is allowed. You will be taken from the "same day unit" or "preadmission area" to the Neuroangiography suite where the procedure will be performed. Just before the procedure, the nurses will shave one or both groins. Embolization is done under general anaesthesia. After the anaesthetic is administered, a catheter will be threaded up a blood vessel in your groin all the way up into the aneurysm. Very tiny catheters are used. This is a similar procedure to a cerebral angiography except that in addition to dye being injected to show the aneurysm, these tiny catheters are positioned near the aneurysm and platinum coils are inserted into the aneurysm to embolize it.

The length of the procedure is often not predictable, and waiting family members need not to be frightened because a case may takes longer than expected. If the doctors do not think that they can safely embolize the aneurysm, then the embolization procedure will be discontinued.

After Treatment 
You will be taken to the Neurosurgical Intensive Care Unit or Step-down Unit where you will be observed closely overnight. Your doctor will instruct you to remain still, lying flat in bed for up to eight hours. This rest period allows the groin artery to heal.

If all goes well, you will be transferred to a neuroscience floor the next day and discharged home the following day. Most patients treated by embolization will also need to return for a follow-up angiogram or magnetic resonance angiogram (MRA), usually performed several months after the treatment to confirm that the outcome of the treatment is stable in time.



 

What are the Side Effects?


The risk of embolization is low. Possible complications include stroke like symptoms such as weakness in one arm or leg, numbness, tingling, speech disturbances and visual problems.

Serious complications such as permanent stroke or death are rare.

The estimated risk should be discussed with your doctor.



 

Detachable balloon occlusion:


Sometimes the size, shape or location of an aneurysm makes coil embolization and surgery impossible. In this case the doctor may choose to block off the parent artery itself. A preliminary test occlusion is often required. A balloon occlusion of the parent artery may be required for an aneurysm at the base of the skull or a very large aneurysm.

A detachable balloon may be placed distal and proximal to the aneurysm. This will permanently close the artery, therefore no blood will reach the aneurysm. The patient is often tested in advance to assure he can tolerate the occlusion of the artery. This is called a balloon test occlusion.




 

Endovascular Treatment (with Stent):

 


Picture shows a stent.

Endovascular treatment for very large inoperable aneurysms may include placing a prosthesis such as a stent in the intracranial vessels. A stent may cover the neck of the aneurysm allowing for safe deposition of coils in the aneurysm without any coil mass protruding into the parent artery.

 


1. When the neck of the aneurysm is too wide, a stent is sometimes necessary to be placed in the parent vessel to hold the coils inside the body of the aneurysm.


(click to see larger image)


2. A catheter with the stent is positioned across the neck of the aneurysm.


(click to see larger image)


3. Another catheter is then positioned to the middle of the aneurysm.  The coils which fill the aneurysm will be deployed from this catheter.


(click to see larger image)


4. The balloon under the stent inflates and expands the stent.  This creates a wall between the aneurysm and the parent vessel.


(click to see larger image)


5. Coils are now deployed into the aneurysm.  With the stent acting as a barrier between the aneurysm and the parent vessel, it is very unlikely that coils will protrude from the aneurysm.


(click to see larger image)


6.  The balloon and catheters are now removed, leaving the stent to hold the coils in place.  Blood can now flow through the parent vessel without entering, the now coil filled, aneurysm.


(click to see larger image)


 
 

Figure 1. - The vertebral artery is injected with contrast (dye) to show the
basilar aneurysm.

 

 

 


Figure 2. - A stent is deployed inside the basilar artery to cover the neck
of the aneurysm and keep the basilar artery open. The stent has fluoroscopic
markers on the ends to help with placement of the stent within the artery.

 

 

Figure 3. - Coils are deployed through the stent to fill the aneurysm.

The stent helps to keep the coils from falling out of the aneurysm.