Glues and Coils

GLUE

One of the more common agents that is used in treating the vein of Galen malformation. Its chemical name is N-acetyl bucrylate and it is a fast setting glue that solidifies when it comes into contact with ‘ionised’substances, such as blood. Contact with blood causes it to polymerise into an inert substance instantaneously and therefore it can be used to block abnormal blood vessels. On its own it cannot be seen by xray imaging equipment, so it needs to be mixed with other substances that make it visible. If the flow is extremely fast an inert powder known as Tantalum is mixed into the glue. This is a black powder and shows the glue up clearly. When the flow in the vessels is slower, the glue can set too quickly unless it is slowed down by the addition of a ‘retarding agent’. This is known as Lipiodol, which is an iodised oil. Judging the degree of retardation provided by the Lipiodol and force of blood flow is important to ensure the glue sets in the right place and the right time. Lipiodol is visible to the x-ray imaging equipment and then it may not be necessary to add Tantalum powder.

Once the glue is set it is a permanent inert block. It does not react with the brain and does not become unblocked once it is fixed.

The FDA now approve of a glue package produced by Cordis, which produces a package containing all the elements likely to be needed. In Europe and Canada, glue can be obtained as a separate substance and mixed with the other agents independently. This is a cheaper alternative!

COILS

Coils are exactly this- coils. They come in different sizes and when they are deployed into blood vessels they precipitate some blockage both by their physical presence and by the fact that they can cause blood to clot. By impeding blood flow they can slow an abnormal communication. Coils in general though do not cause a permanent effective blockage unless they are so tightly packed that many, many coils are used. Their advantage is that they can be deployed by the veins, which is considered safer than by the arteries. Their disadvantage is that often they don’t work. They can also perforate blood vessels causing haemorrhage. Coils were a good option in units that could not use glue for FDA reasons. As glue can be used everywhere now it should be a good goal. Glue is a technically more difficult medium, hence the need for increased training in its use.

We do not recommend coils as a treatment because glue is definitely more effective if used correctly.

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