Adjuncts to Endovascular Embolization/Coiling
Recent technological advances have led to the development of adjunctive devices and techniques to improve the results with endovascular embolization/coiling. These are devices that help coils stay inside the aneurysm sac which can be particularly helpful for aneurysms with wide necks or large aneurysms that in the past were difficult to treat with embolization/coiling.
One such adjunctive device is an intracranial stent. A stent is a metal mesh device in the shape of a pipe or tube which is placed inside the parent artery at the site of the aneurysm to cover the neck of the aneurysm. This helps to keep coils placed in the aneurysm sac to stay inside the sac.
The stents are usually made of nitinol, a high grade metal alloy of nickel and titanium. If you have a stent placed, you will need to be on one or more antiplatelet medicines such as aspirin, clopidogrel, ticlodipine, or others. Consult with your physician.
At the time of the embolization/coiling procedure, or sometimes as a separate treatment, a microcatheter and wire are navigated from the access site (usually the femoral artery in the groin) using x-ray visualization up to the site of the aneurysm in the brain. The stent can either be pushed through the microcatheter and deployed at the intended target, or with certain types of stents, the microcatheter is exchanged for a new microcatheter carrying the stent inside of it ready to deploy at its tip.
Then coils are placed in the aneurysm sac as would be performed as described in the coiling description. Once the procedure is completed, the patient is transferred to the intensive care unit or the recovery room for monitoring and care.
Coils have been the mainstay of endovascular embolization of cerebral aneurysms. Recently there has been the technological development of liquid agents, a surgical glue, for embolization of cerebral aneurysms. Currently, the liquid agent that is available in the United States, is Onyx HD 500 (ethylene vinyl alcholol copolymer dissolved in dimethyl sulfoxide). Onyx HD 500 is a liquid that solidifies when in contact with blood, thus, in the treatment of cerebral aneurysms, Onyx HD 500 is injected via a microcatheter inside of the aneurysm sac, and it solidifies inside the aneurysm sac. A balloon is placed across the neck of the aneurysm and is inflated temporarily to prevent the Onyx HD 500 from leaking outside of the aneurysm sac.
A microcatheter and wire are navigated from the access site (usually the femoral artery in the groin) using x-ray visualization up to the aneurysm in the brain and placed inside the aneurysm sac. A balloon is navigated from the access site up to the parent artery and placed so that it covers the neck of the aneurysm. The balloon is then inflated to block the aneurysm neck. Then dimethyl sulfoxide is injected to fill up the inside of the microcatheter, followed by the Onyx HD 500 which pushes the mixture out into the aneurysm sac. Once in contact with blood, this mixture solidifies and fills up the aneurysm sac. The balloon is deflated periodically to allow restoration of blood flow in the parent artery. Once the aneurysm is filled up with Onyx HD 500, the procedure is completed. The patient is transferred to the intensive care unit or recovery room for monitoring and care.
Pipeline Embolization Device
Approved by the FDA in April 2011, the Pipeline Embolization Device (PED) is a flexible mesh tube made of platinum and nickel-cobalt chromium alloy that can be used to block off large, giant, or wide-necked aneurysms in the internal carotid artery, a major blood vessel supplying blood to the front of the brain. The device can also reduce the likelihood that an aneurysm will rupture.
To implant the device, the Pipeline is attached to the end of a catheter, which is inserted into an artery in the leg. The catheter is threaded into the carotid artery and into position at the aneurysm where the Pipeline is expanded against the walls of the artery and across the neck of the aneurysm, cutting off blood flow to the aneurysm. The blood remaining in the blocked-off aneurysm forms a clot which reduces the likelihood the aneurysm will grow bigger or rupture. Aneurysms successfully treated with the Pipeline will often shrink over time.