Endovascular simply means within the blood vessel. Instead of open surgery, the aneurysm is accessed via a catheter inserted in an artery (usually in the groin or arm, by the wrist) and treated by inserting various devices (coils, stents, balloons, flow diversion devices) that prevent blood from flowing into the aneurysm. Endovascular treatment is also referred to as embolization

The goal of endovascular therapy is the same as surgical treatment: to prevent rupture by safely sealing off the aneurysm from its parent artery

Available since about 1990, endovascular treatment was initially used to treat aneurysms that could not be treated with surgery. The field has developed rapidly so that now endovascular treatment is used as the primary treatment method at many medical centers. Your doctor will discuss the risks and benefits of endovascular treatment with you and your family and answer any questions you may have. 

Coiling Procedure 

Endovascular treatment of aneurysms is most often performed in an angiography suite by a specialized team of doctors, nurses, and technologists. An interventional neuroradiologist or neurosurgeon trained in interventional neuroradiology is the primary doctor during the procedure. 

Prior to the procedure, you will undergo some pre-admission testing (for example, blood tests, an EKG, and chest X-ray). You may also be put on medications to prevent small clots during and after the procedure, usually they start one week prior to the treatment and stop 3 months after the treatment. During the procedure, you will be under sedation or general anesthesia. 

At the time of the procedure, your groin is scrubbed and shaved, usually on both sides. Sterile drapes and cloths are placed over your body, leaving the groin area exposed. A small skin incision, measuring approximately 6 mm (a quarter inch, a dime is 18 mm), is made over the artery and a needle is used to puncture the blood vessel. 

A sheath (thin tube) is then placed in the artery, which provides continual access to the artery. Using X-ray visualization and high-speed filming techniques that provide a continuous view of the normal blood vessels and aneurysm, the doctor inserts a catheter, led by a guide wire, and advances it to the site of the aneurysm. Through the catheter, a smaller microcatheter is advanced into the aneurysm opening and the coil system or flow diversion device is introduced. 

The coil system consists of different materials, most commonly platinum and sometimes other gel-like and suture-like materials. The coils are soft and pliable,and are available in several sizes and shapes to fit correctly inside an aneurysm. 

While inside the catheter, the coil is straight, but when the coil exits the catheter, it takes on a spiral shape, conforming to the shape of the aneurysm. The coil (or coils, as sometimes more than one is needed) prevents blood from flowing into the aneurysm. This causes the blood inside the aneurysm to clot, which destroys the aneurysm. 

Flow diversion devices, such as the Pipeline, have become more common over the past years, and are deployed inside the artery alongside the aneurysm. They are made of a mesh that blocks blood flow through it, correcting the flow in the direction of the artery and no longer into the aneurysm. Within 6 months to 1 year, the aneurysm grows shut and disappears, because blood no longer flows into it. 

After Treatment 
You will be monitored in a recovery area after the procedure. Although rare, there is a risk of blood clots or a stroke associated with endovascular therapy. Drugs to prevent clotting may be used. The length of stay in the hospital varies for each patient. Patients treated for unruptured aneurysms can often go home within 24 hours. Patients with ruptured aneurysms remain in the hospital longer for monitoring of possible vasospasm

Follow-up imaging will need to be done to assess for the stability of the coil or flow diversion device and to make sure the aneurysm does not grow back. Your doctor will tell you when and how often you will need follow-up studies. It is very important to adhere to your follow-up schedule.