Tiny metal coils are deployed within the sac of the aneurysm. Originally these coils were made of platinum but endovascular technology is developing all the time and other materials have been introduced to increase the efficacy of the coils. Fundamentally the goal is that a blood clot will develop around the ball of coils which ultimately will create a scar that prevents blood from entering the aneurysm. Coiling has proven to be a safe and robust treatment for ruptured aneurysms and there are good quality clinical trials demonstrating this. Most endovascular treatments in the UK are carried out by specialist interventional neuroradiologists. The doctors carrying out your treatment will discuss the procedure, its chances of success and its risks beforehand.
The base of the aneurysm can be so wide that the ball of coils may not be retained within the aneurysm at least in the early stage of their deployment. If the coil ball falls into the blood vessel from which the aneurysm arises it may could the vessel causing stroke. This problem may be solved by using a tiny balloon within the vessel to support the coils inside the aneurysm until they are sufficiently packed tightly and the aneurysm secure.
Occasionally the base (or neck) of the aneurysm is too wide for even a tightly packed coil ball to remain within the aneurysm. Improvements in materials technology have allowed the development of expandable metal stents which can be placed within the blood vessel to support the coil ball and ensure blood continues to flow through the blood vessels.
The base of the aneurysm can be so wide that the ball of coils may not be retained within the aneurysm at least in the early stage of their deployment. If the coil ball falls into the blood vessel from which the aneurysm arises it may could the vessel causing stroke. This problem may be solved by using a tiny balloon within the vessel to support the coils inside the aneurysm until they are sufficiently packed tightly and the aneurysm secure. Alternatively the ball of coils may be constrained within the aneurysm using a stent. This is a small metal tube which opens within the the blood vessel. Over time the cells in the interior of the blood vessel (endothelial cells) grow to cover the stent. A pre-requisite for their use is the administration of medication to inhibit blood clots forming within the stent before it is covered by the endothelial cells.
The risks of endovascular treatment of an aneurysm include:
A new generation of endovascular devices called flow diverting stents have recently been approved for use. These stents can divert blood from entering an aneurysm sufficiently to occlude it but allow blood flow to continue into branching vessels emerging from the parent vessel which has given rise to the aneurysm. They may also be combined with coil reinforcement of the aneurysmal dome. An example used regularly in our practice is the Pipeline Embolisation Device (PED) and its deployment is shown in the animation on the left. Your interventional neuroradiologist will be happy to discuss whether your aneurysm would be best treated in this way. As with all new or emerging technologies we are still learning about the limitations as well as the applications of flow diverting stents and their use is reserved for specific aneurysms in our practice.
Another family of novel devices are the intra-aneurysmal flow disrupters. The best known of these currently is the Woven Endo Bridge (WEB) device. Devices like this hold out the possibility of endovascularly treating wide necked aneurysm without the need to administer drugs to inhibit blood clotting.
This type of technology evolves rapidly and allows treatment options for lesions that sometimes could not be safely treated by other means. However it requires time to be certain that new devices are safe and efficacious once in widespread use. If a novel device is being considered as part of your treatment in our practice we encourage you to ask questions of us. We will be happy to provide additional written information about novel devices and discuss alternative approaches. Where possible we look to introduce novel devices in the context of a clinical trial or contribute data to registries.