AVM (Arteriovenous Malformation) and Fistulae
An AVM is an abnormal, tangled web of blood vessels (arteries and veins) in the brain, brainstem or spinal cord. The difference between an artery and a vein is simple: arteries take blood away from the heart and veins take blood into the heart. Arteries have thick walls that allow blood to flow through at a high pressure. Veins have thin walls that allow blood to flow through at a much lower pressure.
When an AVM is present there is an abnormal tangle of veins and arteries. Usually one or more of the tangled arteries is directly connected to one or more veins, which can cause many problems. When a high pressure artery is directly connected to a low pressure vein the most serious problem is blood flowing through the vein at a higher pressure than the vein can handle. Veins cannot handle high pressure blood flow for an extended period of time; the walls of a vein are too weak to support high pressure blood flow from the artery that is connected to it. This abnormal connection between an artery and a vein create an AVM, which can rupture and bleed into the brain.
Arteriovenous Malformation (AVM) and Arteriovenous Fistula (AVF) Treatment
An AVM/AVF can be treated using minimally invasive surgery alone or in combination with traditional open surgery. A Neurointerventional Surgeon will permanently block and close off the vessels of the AVM/AVF, this is called embolization. Materials used to embolize the AVM/AVF might include small platinum coils and/or a liquid embolic agent (a glue-like substance). After the AVM/AVF is embolized the patient may require traditional neurosurgery to remove the AVM/AVF from the brain.
Embolization of an AVM/AVF is usually performed before traditional surgery. The reason an AVM/AVF is embolized before traditional surgery is because embolization is often able to decrease the size of the AVM/AVF, making traditional surgery much safer for the patient. However, the blood flow from certain AVM/AVF’s may be totally blocked by embolization techniques, and no further therapy may be required.